Simple FET Driver...

[Edward Rawde]

\"Rick C\" <gnuarm.deletethisbit@gmail.com> wrote in message
news:95c527d2-518b-4388-a3bd-ac92e9b1f4d9n@googlegroups.com...
On Thursday, December 3, 2020 at 11:39:15 AM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:5f1f4d13-a97e-45c6...@googlegroups.com...
On Wednesday, December 2, 2020 at 10:48:03 PM UTC-5, Edward Rawde wrote:
jla...@highlandsniptechnology.com> wrote in message
news:u3ngsfhkn7u43qs1v...@4ax.com...
On Wed, 2 Dec 2020 17:12:04 -0500, \"Edward Rawde\"
inv...@invalid.invalid> wrote:

\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it
gets
some
shoot through during the switching.

One further thought.
If the problem is what happens when both switches are on then control
them
independently and arrange for that not to be the case.
In other words you need a break before make switchover.
Hang sufficient capacitance on the rail to the motor control circuit
so
it
doesn\'t see the join.


How about using two diodes? Too easy I guess.
Yes a couple of diodes producing Vmain would stop Vin and Vbatt ever
meeting
each other.
Yes, they will do that. But they won\'t allow the rest of the circuit to
work and the reason why has already been covered. It\'s also very obvious
if you look at what the circuit is doing.

In fact, the diodes are already there for the low current always on path.
They work like a champ!

Actually, the predecessor circuit to this one had a FET based diode pair
to
combine the input and battery circuits. But that was with a higher
voltage
input and now we are using a 12 volt input. Use diodes and the battery
will always be powering the circuit until it runs down.
I think some of us are having trouble fully understanding your system
topology. A block diagram may or may not help. In any case, why does it
matter if both switches are on for say 50uS, what is that going to hurt?
If it could possibly hurt anything at all then add a diode so it can\'t.

Why would you use diodes and switches??? I don\'t know if 40 us of shoot
through is an issue. I thought I made that clear in the original
descriptions.

The input powers a buck/boost charger for the battery and powers the switch
selecting the battery or the input power. Is that what you were missing?
You talked about running the entire system off the charging circuit so I
thought you must have understood that, no?

I think we have some communication problems here so I think we should leave
it there.
Let us know how the design review goes.
If there is still an issue after the design review then please include a
system block diagram as well as the relevant schematics.

--

Rick C.

 

[Rick C]

On Thursday, December 3, 2020 at 1:02:54 PM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:95c527d2-518b-4388...@googlegroups.com...
On Thursday, December 3, 2020 at 11:39:15 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:5f1f4d13-a97e-45c6...@googlegroups.com...
On Wednesday, December 2, 2020 at 10:48:03 PM UTC-5, Edward Rawde wrote:
jla...@highlandsniptechnology.com> wrote in message
news:u3ngsfhkn7u43qs1v...@4ax.com...
On Wed, 2 Dec 2020 17:12:04 -0500, \"Edward Rawde\"
inv...@invalid.invalid> wrote:

\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it
gets
some
shoot through during the switching.

One further thought.
If the problem is what happens when both switches are on then control
them
independently and arrange for that not to be the case.
In other words you need a break before make switchover.
Hang sufficient capacitance on the rail to the motor control circuit
so
it
doesn\'t see the join.


How about using two diodes? Too easy I guess.
Yes a couple of diodes producing Vmain would stop Vin and Vbatt ever
meeting
each other.
Yes, they will do that. But they won\'t allow the rest of the circuit to
work and the reason why has already been covered. It\'s also very obvious
if you look at what the circuit is doing.

In fact, the diodes are already there for the low current always on path.
They work like a champ!

Actually, the predecessor circuit to this one had a FET based diode pair
to
combine the input and battery circuits. But that was with a higher
voltage
input and now we are using a 12 volt input. Use diodes and the battery
will always be powering the circuit until it runs down.
I think some of us are having trouble fully understanding your system
topology. A block diagram may or may not help. In any case, why does it
matter if both switches are on for say 50uS, what is that going to hurt?
If it could possibly hurt anything at all then add a diode so it can\'t.

Why would you use diodes and switches??? I don\'t know if 40 us of shoot
through is an issue. I thought I made that clear in the original
descriptions.

The input powers a buck/boost charger for the battery and powers the switch
selecting the battery or the input power. Is that what you were missing?
You talked about running the entire system off the charging circuit so I
thought you must have understood that, no?
I think we have some communication problems here so I think we should leave
it there.
Let us know how the design review goes.
If there is still an issue after the design review then please include a
system block diagram as well as the relevant schematics.

The input protection circuit that was there to meet unstated requirements is gone. With the need for a large power source from a previous motor upgrade the connector changed from a barrel connector to a DIN with 7.5 amp rated contacts, so we are using them in pairs. The likelihood of someone applying an incorrect power source becomes much less so the \"protection\" input circuit is now gone. Oddly enough the guy is opposed to adding a simple fuse and seems to want a resettable circuit breaker.

Much of the design was not ready for review and much of the time was spent discussing connectors and pinouts. I asked what the power off current consumption from the battery was and he didn\'t have the info. There was no signal to provide an indication of presence of input power, just one to indicate that power was within a valid range, but not rated to be valid below 3V. Not much good that!

His approach to the switching circuit is to use the LTC4416 which is a $4 part. It\'s also not at all clear to me that it won\'t have the same shoot through current issue. They don\'t show an example circuit exactly as we are using it with the reverse current flow protection.

--

Rick C.

-++ Get 1,000 miles of free Supercharging
-++ Tesla referral code - https://ts.la/richard11209

 

[Edward Rawde]

\"Rick C\" <gnuarm.deletethisbit@gmail.com> wrote in message
news:7fa3cff0-aa6d-4aa6-af9f-dd3b2282ae3an@googlegroups.com...
On Thursday, December 3, 2020 at 1:02:54 PM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:95c527d2-518b-4388...@googlegroups.com...
On Thursday, December 3, 2020 at 11:39:15 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:5f1f4d13-a97e-45c6...@googlegroups.com...
On Wednesday, December 2, 2020 at 10:48:03 PM UTC-5, Edward Rawde wrote:
jla...@highlandsniptechnology.com> wrote in message
news:u3ngsfhkn7u43qs1v...@4ax.com...
On Wed, 2 Dec 2020 17:12:04 -0500, \"Edward Rawde\"
inv...@invalid.invalid> wrote:

\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it
gets
some
shoot through during the switching.

One further thought.
If the problem is what happens when both switches are on then
control
them
independently and arrange for that not to be the case.
In other words you need a break before make switchover.
Hang sufficient capacitance on the rail to the motor control circuit
so
it
doesn\'t see the join.


How about using two diodes? Too easy I guess.
Yes a couple of diodes producing Vmain would stop Vin and Vbatt ever
meeting
each other.
Yes, they will do that. But they won\'t allow the rest of the circuit to
work and the reason why has already been covered. It\'s also very
obvious
if you look at what the circuit is doing.

In fact, the diodes are already there for the low current always on
path.
They work like a champ!

Actually, the predecessor circuit to this one had a FET based diode
pair
to
combine the input and battery circuits. But that was with a higher
voltage
input and now we are using a 12 volt input. Use diodes and the battery
will always be powering the circuit until it runs down.
I think some of us are having trouble fully understanding your system
topology. A block diagram may or may not help. In any case, why does it
matter if both switches are on for say 50uS, what is that going to hurt?
If it could possibly hurt anything at all then add a diode so it can\'t.

Why would you use diodes and switches??? I don\'t know if 40 us of shoot
through is an issue. I thought I made that clear in the original
descriptions.

The input powers a buck/boost charger for the battery and powers the
switch
selecting the battery or the input power. Is that what you were missing?
You talked about running the entire system off the charging circuit so I
thought you must have understood that, no?
I think we have some communication problems here so I think we should
leave
it there.
Let us know how the design review goes.
If there is still an issue after the design review then please include a
system block diagram as well as the relevant schematics.

The input protection circuit that was there to meet unstated requirements
is gone. With the need for a large power source from a previous motor
upgrade the connector changed from a barrel connector to a DIN with 7.5 amp
rated contacts, so we are using them in pairs. The likelihood of someone
applying an incorrect power source becomes much less so the \"protection\"
input circuit is now gone. Oddly enough the guy is opposed to adding a
simple fuse and seems to want a resettable circuit breaker.

I\'d have a simple fuse in series with the battery. Fuses do sometimes suffer
from the customer mentality of \"the fuse nust be faulty because it keeps
blowing so I\'ll put metal foil around it\" so some kind of breaker may be
better in some cases if it can\'t be forced on when it doesn\'t want to be on.

Much of the design was not ready for review and much of the time was spent
discussing connectors and pinouts. I asked what the power off current
consumption from the battery was and he didn\'t have the info. There was no
signal to provide an indication of presence of input power, just one to
indicate that power was within a valid range, but not rated to be valid
below 3V. Not much good that!

His approach to the switching circuit is to use the LTC4416 which is a $4
part. It\'s also not at all clear to me that it won\'t have the same shoot
through current issue. They don\'t show an example circuit exactly as we
are using it with the reverse current flow protection.

--

Rick C.

 

[Rick C]

On Thursday, December 3, 2020 at 4:10:46 PM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:7fa3cff0-aa6d-4aa6...@googlegroups.com...
On Thursday, December 3, 2020 at 1:02:54 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:95c527d2-518b-4388...@googlegroups.com...
On Thursday, December 3, 2020 at 11:39:15 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:5f1f4d13-a97e-45c6...@googlegroups.com...
On Wednesday, December 2, 2020 at 10:48:03 PM UTC-5, Edward Rawde wrote:
jla...@highlandsniptechnology.com> wrote in message
news:u3ngsfhkn7u43qs1v...@4ax.com...
On Wed, 2 Dec 2020 17:12:04 -0500, \"Edward Rawde\"
inv...@invalid.invalid> wrote:

\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it
gets
some
shoot through during the switching.

One further thought.
If the problem is what happens when both switches are on then
control
them
independently and arrange for that not to be the case.
In other words you need a break before make switchover.
Hang sufficient capacitance on the rail to the motor control circuit
so
it
doesn\'t see the join.


How about using two diodes? Too easy I guess.
Yes a couple of diodes producing Vmain would stop Vin and Vbatt ever
meeting
each other.
Yes, they will do that. But they won\'t allow the rest of the circuit to
work and the reason why has already been covered. It\'s also very
obvious
if you look at what the circuit is doing.

In fact, the diodes are already there for the low current always on
path.
They work like a champ!

Actually, the predecessor circuit to this one had a FET based diode
pair
to
combine the input and battery circuits. But that was with a higher
voltage
input and now we are using a 12 volt input. Use diodes and the battery
will always be powering the circuit until it runs down.
I think some of us are having trouble fully understanding your system
topology. A block diagram may or may not help. In any case, why does it
matter if both switches are on for say 50uS, what is that going to hurt?
If it could possibly hurt anything at all then add a diode so it can\'t.

Why would you use diodes and switches??? I don\'t know if 40 us of shoot
through is an issue. I thought I made that clear in the original
descriptions.

The input powers a buck/boost charger for the battery and powers the
switch
selecting the battery or the input power. Is that what you were missing?
You talked about running the entire system off the charging circuit so I
thought you must have understood that, no?
I think we have some communication problems here so I think we should
leave
it there.
Let us know how the design review goes.
If there is still an issue after the design review then please include a
system block diagram as well as the relevant schematics.

The input protection circuit that was there to meet unstated requirements
is gone. With the need for a large power source from a previous motor
upgrade the connector changed from a barrel connector to a DIN with 7.5 amp
rated contacts, so we are using them in pairs. The likelihood of someone
applying an incorrect power source becomes much less so the \"protection\"
input circuit is now gone. Oddly enough the guy is opposed to adding a
simple fuse and seems to want a resettable circuit breaker.
I\'d have a simple fuse in series with the battery. Fuses do sometimes suffer
from the customer mentality of \"the fuse nust be faulty because it keeps
blowing so I\'ll put metal foil around it\" so some kind of breaker may be
better in some cases if it can\'t be forced on when it doesn\'t want to be on.
Much of the design was not ready for review and much of the time was spent
discussing connectors and pinouts. I asked what the power off current
consumption from the battery was and he didn\'t have the info. There was no
signal to provide an indication of presence of input power, just one to
indicate that power was within a valid range, but not rated to be valid
below 3V. Not much good that!

His approach to the switching circuit is to use the LTC4416 which is a $4
part. It\'s also not at all clear to me that it won\'t have the same shoot
through current issue. They don\'t show an example circuit exactly as we
are using it with the reverse current flow protection.

There are some things I don\'t care about protecting a person from. At some point if stupidity is extreme or deliberate enough, I\'m just not going to worry about it.

--

Rick C.

+-- Get 1,000 miles of free Supercharging
+-- Tesla referral code - https://ts.la/richard11209

 

[Edward Rawde]

\"Edward Rawde\" <invalid@invalid.invalid> wrote in message
news:rq8q5r$l3r$1@gioia.aioe.org...

\"Rick C\" <gnuarm.deletethisbit@gmail.com> wrote in message
news:6fce9360-b9e9-450f-b078-02ff237ed2d9n@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it gets some
shoot through during the switching.

I\'d probably use something like the N channel circuit on this page:
https://www.homemade-circuits.com/bidirectional-switch/
With a suitable Vaux supply for both switches.

If your existing circuit has issues with switching speed then adjust the
resistors in the gate drive circuit for a suitable speed.
Watch out for your FET\'s maximum 8V gate-source rating.

If I were doing the entire system from scratch and if I had control of the
design of the AC power line to DC power supply then I\'d use one suitably
rated power supply to charge the battery and provide the load current.
I\'d sense the battery charging current with a suitably rated low value
series resistor and feed that back to control the rail voltage.
The motor driving circuit would be designed to work over whatever voltage is
available between low voltage cutout (assuming the type of battery needs it)
and maximum battery charging current.
The only power switch I might then need is to disconnect the battery before
over discharge.

 

[Edward Rawde]

\"Edward Rawde\" <invalid@invalid.invalid> wrote in message
news:rq8q5r$l3r$1@gioia.aioe.org...

\"Rick C\" <gnuarm.deletethisbit@gmail.com> wrote in message
news:6fce9360-b9e9-450f-b078-02ff237ed2d9n@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it gets some
shoot through during the switching.

One further thought.
If the problem is what happens when both switches are on then control them
independently and arrange for that not to be the case.
In other words you need a break before make switchover.
Hang sufficient capacitance on the rail to the motor control circuit so it
doesn\'t see the join.

 

[Rick C]

On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde wrote:

\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it gets some
shoot through during the switching.
I\'d probably use something like the N channel circuit on this page:
https://www.homemade-circuits.com/bidirectional-switch/
With a suitable Vaux supply for both switches.

If your existing circuit has issues with switching speed then adjust the
resistors in the gate drive circuit for a suitable speed.
Watch out for your FET\'s maximum 8V gate-source rating.

If I were doing the entire system from scratch and if I had control of the
design of the AC power line to DC power supply then I\'d use one suitably
rated power supply to charge the battery and provide the load current.
I\'d sense the battery charging current with a suitably rated low value
series resistor and feed that back to control the rail voltage.
The motor driving circuit would be designed to work over whatever voltage is
available between low voltage cutout (assuming the type of battery needs it)
and maximum battery charging current.
The only power switch I might then need is to disconnect the battery before
over discharge.

I know why you are say that, but that is the wrong approach. The motor is rated for 12 volts and they make express caution against driving with too much voltage. Charge the battery to 14.5 volts (the stated 100% charged point) while running the motor from that and it can cause premature failure. The battery is the power source only when the input power is off at which point the battery itself is not even 13.5 volts minus the internal resistance times the 10 amp peak current steadily dropping as it is drained over a 20 minute period. Meanwhile the motor runs on 12 volts for 99.99% of the time directly from the DC input of the external PSU.

Trying to adapt the motor driving circuit is not the better way to do this. I\'m asking for help switching between two power sources which is not hard to do. If you can\'t help with that, I understand. But you don\'t need to rain on the design approach when you don\'t understand the constraints.

Tell you what, if you\'d like to join the team, we would appreciate your inputs. The power circuits are on a separate board from the rest of the design and the guy is mostly done with that board. He has not yet provided the required power down control. He has a switching circuit using a $4 LT chip which I think is not needed. I have a design that works using just $0.10 transistors to control the power FETs, but they are a bit slow to turn off, so there is shoot through current for some 40 us. That\'s what I\'m trying to improve on, even though it doesn\'t seem like a problem.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

 

[Edward Rawde]

\"Rick C\" <gnuarm.deletethisbit@gmail.com> wrote in message
news:e4285dd9-ed97-4189-a1af-37204558bb7fn@googlegroups.com...
On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde wrote:

\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it gets
some
shoot through during the switching.
I\'d probably use something like the N channel circuit on this page:
https://www.homemade-circuits.com/bidirectional-switch/
With a suitable Vaux supply for both switches.

If your existing circuit has issues with switching speed then adjust the
resistors in the gate drive circuit for a suitable speed.
Watch out for your FET\'s maximum 8V gate-source rating.

If I were doing the entire system from scratch and if I had control of the
design of the AC power line to DC power supply then I\'d use one suitably
rated power supply to charge the battery and provide the load current.
I\'d sense the battery charging current with a suitably rated low value
series resistor and feed that back to control the rail voltage.
The motor driving circuit would be designed to work over whatever voltage
is
available between low voltage cutout (assuming the type of battery needs
it)
and maximum battery charging current.
The only power switch I might then need is to disconnect the battery
before
over discharge.

I know why you are say that, but that is the wrong approach. The motor is
rated for 12 volts and they make express caution against driving with too
much voltage. Charge the battery to 14.5 volts (the stated 100% charged
point) while running the motor from that and it can cause premature
failure.

But the motor is not connected directly to the battery is it? It\'s driven by
PWM from the motor control circuit which can provide it with any drive level
it requires. It never has to get more than 12V if the PWM circuit is
designed so that it never provides more than 12V average drive to the motor.
I\'d have the motor drive power controlled by sensors sensing what the motor
is doing so I don\'t have to worry about over driving the motor.

The battery is the power source only when the input power is off at which
point the battery itself is not even 13.5 volts minus the internal
resistance times the 10 amp peak current steadily dropping as it is drained
over a 20 minute period. Meanwhile the motor runs on 12 volts for 99.99%
of the time directly from the DC input of the external PSU.

Trying to adapt the motor driving circuit is not the better way to do this.
I\'m asking for help switching between two power sources which is not hard
to do. If you can\'t help with that, I understand. But you don\'t need to
rain on the design approach when you don\'t understand the constraints.

I agree it\'s not hard to switch between two power sources so where\'s the
difficulty?
Control the switches in a break before make fashion if you have to.
Or just adjust the RC timing (gate resistors and gate/source capaciatnce).

Tell you what, if you\'d like to join the team, we would appreciate your
inputs.

I don\'t think I\'m in the same country as you. I have done design by email
before but for your type of system I\'d prefer to be able to do lab tests
before committing the design.

The power circuits are on a separate board from the rest of the design and
the guy is mostly done with that board. He has not yet provided the
required power down control. He has a switching circuit using a $4 LT chip
which I think is not needed. I have a design that works using just $0.10
transistors to control the power FETs, but they are a bit slow to turn off,
so there is shoot through current for some 40 us. That\'s what I\'m trying
to improve on, even though it doesn\'t seem like a problem.

--

Rick C.

 

[Rick C]

On Wednesday, December 2, 2020 at 5:46:57 PM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e4285dd9-ed97-4189...@googlegroups.com...
On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde wrote:
\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it gets
some
shoot through during the switching.
I\'d probably use something like the N channel circuit on this page:
https://www.homemade-circuits.com/bidirectional-switch/
With a suitable Vaux supply for both switches.

If your existing circuit has issues with switching speed then adjust the
resistors in the gate drive circuit for a suitable speed.
Watch out for your FET\'s maximum 8V gate-source rating.

If I were doing the entire system from scratch and if I had control of the
design of the AC power line to DC power supply then I\'d use one suitably
rated power supply to charge the battery and provide the load current.
I\'d sense the battery charging current with a suitably rated low value
series resistor and feed that back to control the rail voltage.
The motor driving circuit would be designed to work over whatever voltage
is
available between low voltage cutout (assuming the type of battery needs
it)
and maximum battery charging current.
The only power switch I might then need is to disconnect the battery
before
over discharge.

I know why you are say that, but that is the wrong approach. The motor is
rated for 12 volts and they make express caution against driving with too
much voltage. Charge the battery to 14.5 volts (the stated 100% charged
point) while running the motor from that and it can cause premature
failure.
But the motor is not connected directly to the battery is it? It\'s driven by
PWM from the motor control circuit which can provide it with any drive level
it requires. It never has to get more than 12V if the PWM circuit is
designed so that it never provides more than 12V average drive to the motor.
I\'d have the motor drive power controlled by sensors sensing what the motor
is doing so I don\'t have to worry about over driving the motor.

If you\'d like to get involved in designing the motor control loop you would be VERY welcome. Right now they seem to have little skill in that area and are initially banging the motor with full current for some period at the beginning of the cycle. I\'d love to hear you discuss this with the two guys designing the PID, your head would explode!

The battery is the power source only when the input power is off at which
point the battery itself is not even 13.5 volts minus the internal
resistance times the 10 amp peak current steadily dropping as it is drained
over a 20 minute period. Meanwhile the motor runs on 12 volts for 99.99%
of the time directly from the DC input of the external PSU.

Trying to adapt the motor driving circuit is not the better way to do this.
I\'m asking for help switching between two power sources which is not hard
to do. If you can\'t help with that, I understand. But you don\'t need to
rain on the design approach when you don\'t understand the constraints.
I agree it\'s not hard to switch between two power sources so where\'s the
difficulty?

What part of what I\'ve explained is not clear? Didn\'t I indicate the reason for wanting to use a push-pull arrangement of a CMOS logic device rather than the slow pull up on an open drain FET driver? There is 40 us of shoot through. With a push-pull drive on the gates of the power FETs I expect this can be reduced to nanoseconds.

Control the switches in a break before make fashion if you have to.
Or just adjust the RC timing (gate resistors and gate/source capaciatnce)..

Are there any specific suggestions to the two schematics I uploaded?

Tell you what, if you\'d like to join the team, we would appreciate your
inputs.
I don\'t think I\'m in the same country as you. I have done design by email
before but for your type of system I\'d prefer to be able to do lab tests
before committing the design.

Lab tests on what exactly? You mean you want to prototype the design? We ship things around. That\'s not a problem. Oh, I\'m not in the same country as much of the team. Some in the UK, some elsewhere in the EU, one in Turkey... or India... I can\'t recall... then some in the US.

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

 

[Edward Rawde]

\"Rick C\" <gnuarm.deletethisbit@gmail.com> wrote in message
news:7d3d16b5-aaef-49f9-95bd-1c00f8dc3cddn@googlegroups.com...
On Wednesday, December 2, 2020 at 5:46:57 PM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e4285dd9-ed97-4189...@googlegroups.com...
On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde wrote:
\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it gets
some
shoot through during the switching.
I\'d probably use something like the N channel circuit on this page:
https://www.homemade-circuits.com/bidirectional-switch/
With a suitable Vaux supply for both switches.

If your existing circuit has issues with switching speed then adjust the
resistors in the gate drive circuit for a suitable speed.
Watch out for your FET\'s maximum 8V gate-source rating.

If I were doing the entire system from scratch and if I had control of
the
design of the AC power line to DC power supply then I\'d use one suitably
rated power supply to charge the battery and provide the load current.
I\'d sense the battery charging current with a suitably rated low value
series resistor and feed that back to control the rail voltage.
The motor driving circuit would be designed to work over whatever
voltage
is
available between low voltage cutout (assuming the type of battery needs
it)
and maximum battery charging current.
The only power switch I might then need is to disconnect the battery
before
over discharge.

I know why you are say that, but that is the wrong approach. The motor is
rated for 12 volts and they make express caution against driving with too
much voltage. Charge the battery to 14.5 volts (the stated 100% charged
point) while running the motor from that and it can cause premature
failure.
But the motor is not connected directly to the battery is it? It\'s driven
by
PWM from the motor control circuit which can provide it with any drive
level
it requires. It never has to get more than 12V if the PWM circuit is
designed so that it never provides more than 12V average drive to the
motor.
I\'d have the motor drive power controlled by sensors sensing what the
motor
is doing so I don\'t have to worry about over driving the motor.

If you\'d like to get involved in designing the motor control loop you
would be VERY welcome. Right now they seem to have little skill in that
area and are initially banging the motor with full current for some period
at the beginning of the cycle. I\'d love to hear you discuss this with the
two guys designing the PID, your head would explode!

Well if you don\'t have people with the required skills then recruit them.
I think I\'d prefer not to get personally involved.

The battery is the power source only when the input power is off at which
point the battery itself is not even 13.5 volts minus the internal
resistance times the 10 amp peak current steadily dropping as it is
drained
over a 20 minute period. Meanwhile the motor runs on 12 volts for 99.99%
of the time directly from the DC input of the external PSU.

Trying to adapt the motor driving circuit is not the better way to do
this.
I\'m asking for help switching between two power sources which is not hard
to do. If you can\'t help with that, I understand. But you don\'t need to
rain on the design approach when you don\'t understand the constraints.
I agree it\'s not hard to switch between two power sources so where\'s the
difficulty?

What part of what I\'ve explained is not clear? Didn\'t I indicate the
reason for wanting to use a push-pull arrangement of a CMOS logic device
rather than the slow pull up on an open drain FET driver? There is 40 us
of shoot through. With a push-pull drive on the gates of the power FETs I
expect this can be reduced to nanoseconds.

I\'d use a purpose designed gate driver if there was a good reason to have
very fast switching speed.
I think you can do without that for a power on/off switch.

Control the switches in a break before make fashion if you have to.
Or just adjust the RC timing (gate resistors and gate/source capaciatnce).

Are there any specific suggestions to the two schematics I uploaded?

Consider a redesign of the power switches using this page as a reference.
https://www.homemade-circuits.com/bidirectional-switch/
Bearing in mind the switching speed you need and the 8V maximum gate-source
voltage for your FETs.
Why 10K resistors? 12V across 1K is only 0.14 Watts.
Making the resistors smaller will charge/discharge the capacitance quicker
making it switch quicker.
If overlap is still an issue then control the switches independently to get
suitable break before make switching.

Tell you what, if you\'d like to join the team, we would appreciate your
inputs.
I don\'t think I\'m in the same country as you. I have done design by email
before but for your type of system I\'d prefer to be able to do lab tests
before committing the design.

Lab tests on what exactly? You mean you want to prototype the design? We
ship things around. That\'s not a problem. Oh, I\'m not in the same
country as much of the team. Some in the UK, some elsewhere in the EU, one
in Turkey... or India... I can\'t recall... then some in the US.

I\'ve seen more than a few projects cancelled because the hardware was done
in one country and the software in another.
Having the team distributed around the world isn\'t necessarily an issue as
long as someone who knows what they\'re doing is in overall charge.
I don\'t think there is much else I can do for you.

--

Rick C.

 

[Rick C]

On Wednesday, December 2, 2020 at 7:09:55 PM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:7d3d16b5-aaef-49f9...@googlegroups.com...
On Wednesday, December 2, 2020 at 5:46:57 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e4285dd9-ed97-4189...@googlegroups.com...
On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde wrote:
\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it gets
some
shoot through during the switching.
I\'d probably use something like the N channel circuit on this page:
https://www.homemade-circuits.com/bidirectional-switch/
With a suitable Vaux supply for both switches.

If your existing circuit has issues with switching speed then adjust the
resistors in the gate drive circuit for a suitable speed.
Watch out for your FET\'s maximum 8V gate-source rating.

If I were doing the entire system from scratch and if I had control of
the
design of the AC power line to DC power supply then I\'d use one suitably
rated power supply to charge the battery and provide the load current..
I\'d sense the battery charging current with a suitably rated low value
series resistor and feed that back to control the rail voltage.
The motor driving circuit would be designed to work over whatever
voltage
is
available between low voltage cutout (assuming the type of battery needs
it)
and maximum battery charging current.
The only power switch I might then need is to disconnect the battery
before
over discharge.

I know why you are say that, but that is the wrong approach. The motor is
rated for 12 volts and they make express caution against driving with too
much voltage. Charge the battery to 14.5 volts (the stated 100% charged
point) while running the motor from that and it can cause premature
failure.
But the motor is not connected directly to the battery is it? It\'s driven
by
PWM from the motor control circuit which can provide it with any drive
level
it requires. It never has to get more than 12V if the PWM circuit is
designed so that it never provides more than 12V average drive to the
motor.
I\'d have the motor drive power controlled by sensors sensing what the
motor
is doing so I don\'t have to worry about over driving the motor.

If you\'d like to get involved in designing the motor control loop you
would be VERY welcome. Right now they seem to have little skill in that
area and are initially banging the motor with full current for some period
at the beginning of the cycle. I\'d love to hear you discuss this with the
two guys designing the PID, your head would explode!
Well if you don\'t have people with the required skills then recruit them.
I think I\'d prefer not to get personally involved.

Ok, armchair engineering.

The battery is the power source only when the input power is off at which
point the battery itself is not even 13.5 volts minus the internal
resistance times the 10 amp peak current steadily dropping as it is
drained
over a 20 minute period. Meanwhile the motor runs on 12 volts for 99.99%
of the time directly from the DC input of the external PSU.

Trying to adapt the motor driving circuit is not the better way to do
this.
I\'m asking for help switching between two power sources which is not hard
to do. If you can\'t help with that, I understand. But you don\'t need to
rain on the design approach when you don\'t understand the constraints.
I agree it\'s not hard to switch between two power sources so where\'s the
difficulty?

What part of what I\'ve explained is not clear? Didn\'t I indicate the
reason for wanting to use a push-pull arrangement of a CMOS logic device
rather than the slow pull up on an open drain FET driver? There is 40 us
of shoot through. With a push-pull drive on the gates of the power FETs I
expect this can be reduced to nanoseconds.
I\'d use a purpose designed gate driver if there was a good reason to have
very fast switching speed.
I think you can do without that for a power on/off switch.

Yes, that\'s why I am looking at CMOS logic gates, not fast, not high current drive, but maybe good enough. I don\'t know if I\'ll find an adequate simulation model though.

Control the switches in a break before make fashion if you have to.
Or just adjust the RC timing (gate resistors and gate/source capaciatnce).

Are there any specific suggestions to the two schematics I uploaded?
Consider a redesign of the power switches using this page as a reference.
https://www.homemade-circuits.com/bidirectional-switch/
Bearing in mind the switching speed you need and the 8V maximum gate-source
voltage for your FETs.

I don\'t know where you are getting this 8 volt number. You need to check the data sheets again.

I don\'t see how that web page is useful. The intent is not to allow current flow in both directions but to prevent it. To prevent the body diode from conducting current a second FET is used. Then I would point out the circuits on that page use a 10K pull up resistor which is what I am using. This is the cause of the slow turn off time. They don\'t really discuss the circuit other than at a fairly superficial level.


> Why 10K resistors? 12V across 1K is only 0.14 Watts.

As opposed to what? You ask questions like this rather than making suggestions other than tossing the whole thing out and starting over.

I had actually started with rather large resistors because of current drain on the battery, until I realized the only time they matter is when BOTH circuits are off when the driver FETs are off and there is no current flow. So 10K got something that worked ok. As is true with many LTspice simulations change one component value and the circuit can\'t find it\'s starting point. Right now the thing is stuck looking for a way forward and won\'t respond to the esc key. That\'s from changing the 10K values to 4.7K. lol The current doesn\'t get larger, but the time does narrow, but not so fast. That\'s why I\'m thinking a pullup transistor would be a good thing.

Making the resistors smaller will charge/discharge the capacitance quicker
making it switch quicker.

Yes, but \"quicker\" may be better, but is it good enough? At some point the resistor passes as much current as the FET.

If overlap is still an issue then control the switches independently to get
suitable break before make switching.

Independent as in how? They are independent from the state of the comparator. It\'s even worse to have a time of no conduction to either power source.. In reality, the DC in will only drop out when power is lost or something similar, so current into it is not a big deal. When power is restored it the time I\'m worried about. But I don\'t know if it matters that the input is connected to the battery for 40 us.

Tell you what, if you\'d like to join the team, we would appreciate your
inputs.
I don\'t think I\'m in the same country as you. I have done design by email
before but for your type of system I\'d prefer to be able to do lab tests
before committing the design.

Lab tests on what exactly? You mean you want to prototype the design? We
ship things around. That\'s not a problem. Oh, I\'m not in the same
country as much of the team. Some in the UK, some elsewhere in the EU, one
in Turkey... or India... I can\'t recall... then some in the US.
I\'ve seen more than a few projects cancelled because the hardware was done
in one country and the software in another.
Having the team distributed around the world isn\'t necessarily an issue as
long as someone who knows what they\'re doing is in overall charge.
I don\'t think there is much else I can do for you.

Yes, I have that impression.

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

 

[Edward Rawde]

\"Rick C\" <gnuarm.deletethisbit@gmail.com> wrote in message
news:f9beb047-d324-4bbf-a9aa-de4a12a3628bn@googlegroups.com...
On Wednesday, December 2, 2020 at 7:09:55 PM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:7d3d16b5-aaef-49f9...@googlegroups.com...
On Wednesday, December 2, 2020 at 5:46:57 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e4285dd9-ed97-4189...@googlegroups.com...
On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde wrote:
\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it
gets
some
shoot through during the switching.
[...]
Having the team distributed around the world isn\'t necessarily an issue as
long as someone who knows what they\'re doing is in overall charge.
I don\'t think there is much else I can do for you.

Yes, I have that impression.

In that case I won\'t bother responding to your other points except to point
out that your schematics show AO6407 FETs, the data sheet for which is
trivial to find.
Under Absolute Maximum Ratings Vgs is listed as +/- 8V Maximum.
If you want intermittent failures after production has started, just hit it
with 12V.

--

Rick C.

 

[Rick C]

On Wednesday, December 2, 2020 at 9:32:45 PM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:f9beb047-d324-4bbf...@googlegroups.com...
On Wednesday, December 2, 2020 at 7:09:55 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:7d3d16b5-aaef-49f9...@googlegroups.com...
On Wednesday, December 2, 2020 at 5:46:57 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e4285dd9-ed97-4189...@googlegroups.com...
On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde wrote:
\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it
gets
some
shoot through during the switching.
[...]
Having the team distributed around the world isn\'t necessarily an issue as
long as someone who knows what they\'re doing is in overall charge.
I don\'t think there is much else I can do for you.

Yes, I have that impression.
In that case I won\'t bother responding to your other points except to point
out that your schematics show AO6407 FETs, the data sheet for which is
trivial to find.
Under Absolute Maximum Ratings Vgs is listed as +/- 8V Maximum.
If you want intermittent failures after production has started, just hit it
with 12V.

Ok, my bad. I thought I had checked that but I got something wrong. The parts on the board are something else, these were picked for the simulation because they are in the LTspice library. I get tired of fighting the tool to get third party models to work.

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

 

[server]

On Wed, 2 Dec 2020 17:12:04 -0500, \"Edward Rawde\"
<invalid@invalid.invalid> wrote:

\"Edward Rawde\" <invalid@invalid.invalid> wrote in message
news:rq8q5r$l3r$1@gioia.aioe.org...
\"Rick C\" <gnuarm.deletethisbit@gmail.com> wrote in message
news:6fce9360-b9e9-450f-b078-02ff237ed2d9n@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it gets some
shoot through during the switching.

One further thought.
If the problem is what happens when both switches are on then control them
independently and arrange for that not to be the case.
In other words you need a break before make switchover.
Hang sufficient capacitance on the rail to the motor control circuit so it
doesn\'t see the join.

How about using two diodes? Too easy I guess.





--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[Edward Rawde]

\"Rick C\" <gnuarm.deletethisbit@gmail.com> wrote in message
news:e2357c8a-f038-477a-b831-117e8ee57bden@googlegroups.com...
On Wednesday, December 2, 2020 at 9:32:45 PM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:f9beb047-d324-4bbf...@googlegroups.com...
On Wednesday, December 2, 2020 at 7:09:55 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:7d3d16b5-aaef-49f9...@googlegroups.com...
On Wednesday, December 2, 2020 at 5:46:57 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e4285dd9-ed97-4189...@googlegroups.com...
On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde
wrote:
\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it
gets
some
shoot through during the switching.
[...]
Having the team distributed around the world isn\'t necessarily an issue
as
long as someone who knows what they\'re doing is in overall charge.
I don\'t think there is much else I can do for you.

Yes, I have that impression.
In that case I won\'t bother responding to your other points except to
point
out that your schematics show AO6407 FETs, the data sheet for which is
trivial to find.
Under Absolute Maximum Ratings Vgs is listed as +/- 8V Maximum.
If you want intermittent failures after production has started, just hit
it
with 12V.

Ok, my bad. I thought I had checked that but I got something wrong. The
parts on the board are something else, these were picked for the simulation
because they are in the LTspice library. I get tired of fighting the tool
to get third party models to work.

That\'s ok, I\'ve made worse design errors. I think resistors lower than 10K
and a circuit similar to the one on that web site will switch fast enough if
you pay attention to resistor power dissipation and Vgs max. R14 and R15 may
not be needed or can be a lot lower than 10K. Try a simulation with 4.7K and
100 ohms. You never did tell me what D3 is for. I haven\'t used 4000B logic
for um never mind how long. Is it still in production?

--

Rick C.

 

[Edward Rawde]

<jlarkin@highlandsniptechnology.com> wrote in message
news:u3ngsfhkn7u43qs1voft5nsgu6741c8coo@4ax.com...

On Wed, 2 Dec 2020 17:12:04 -0500, \"Edward Rawde\"
invalid@invalid.invalid> wrote:

\"Edward Rawde\" <invalid@invalid.invalid> wrote in message
news:rq8q5r$l3r$1@gioia.aioe.org...
\"Rick C\" <gnuarm.deletethisbit@gmail.com> wrote in message
news:6fce9360-b9e9-450f-b078-02ff237ed2d9n@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it gets
some
shoot through during the switching.

One further thought.
If the problem is what happens when both switches are on then control them
independently and arrange for that not to be the case.
In other words you need a break before make switchover.
Hang sufficient capacitance on the rail to the motor control circuit so it
doesn\'t see the join.


How about using two diodes? Too easy I guess.

Yes a couple of diodes producing Vmain would stop Vin and Vbatt ever meeting
each other.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

 

[Bill Sloman]

On Thursday, December 3, 2020 at 2:39:20 PM UTC+11, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2357c8a-f038-477a...@googlegroups.com...
On Wednesday, December 2, 2020 at 9:32:45 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:f9beb047-d324-4bbf...@googlegroups.com...
On Wednesday, December 2, 2020 at 7:09:55 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:7d3d16b5-aaef-49f9...@googlegroups.com...
On Wednesday, December 2, 2020 at 5:46:57 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e4285dd9-ed97-4189...@googlegroups.com...
On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde
wrote:
\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it
gets
some
shoot through during the switching.
[...]
Having the team distributed around the world isn\'t necessarily an issue
as
long as someone who knows what they\'re doing is in overall charge.
I don\'t think there is much else I can do for you.

Yes, I have that impression.
In that case I won\'t bother responding to your other points except to
point
out that your schematics show AO6407 FETs, the data sheet for which is
trivial to find.
Under Absolute Maximum Ratings Vgs is listed as +/- 8V Maximum.
If you want intermittent failures after production has started, just hit
it
with 12V.

Ok, my bad. I thought I had checked that but I got something wrong. The
parts on the board are something else, these were picked for the simulation
because they are in the LTspice library. I get tired of fighting the tool
to get third party models to work.
That\'s ok, I\'ve made worse design errors. I think resistors lower than 10K
and a circuit similar to the one on that web site will switch fast enough if
you pay attention to resistor power dissipation and Vgs max. R14 and R15 may
not be needed or can be a lot lower than 10K. Try a simulation with 4.7K and
100 ohms. You never did tell me what D3 is for. I haven\'t used 4000B logic
for um never mind how long. Is it still in production?

Element-14 in Australia (it used to be Farnell /Newark) has 306 different parts in stock that fit CD40**. Everything in the first sheet is labelled a \"best seller\", so it does seem to be still in production. Most if it will probably go into legacy products, but I certainly ran into design problems all though my career where logic that could run slowly from an up to 18V supply was just the solution I needed. Unlike the 555 which seems to persist because some designers are lazy and unimaginative, there weren\'t any better alternatives.

--
Bill Sloman, Sydney

 

[Edward Rawde]

\"Bill Sloman\" <bill.sloman@ieee.org> wrote in message
news:b96cd3a0-1bbf-46bc-8018-e0280b36f16en@googlegroups.com...
On Thursday, December 3, 2020 at 2:39:20 PM UTC+11, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2357c8a-f038-477a...@googlegroups.com...
On Wednesday, December 2, 2020 at 9:32:45 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:f9beb047-d324-4bbf...@googlegroups.com...
On Wednesday, December 2, 2020 at 7:09:55 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:7d3d16b5-aaef-49f9...@googlegroups.com...
On Wednesday, December 2, 2020 at 5:46:57 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e4285dd9-ed97-4189...@googlegroups.com...
On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde
wrote:
\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it
gets
some
shoot through during the switching.
[...]
Having the team distributed around the world isn\'t necessarily an
issue
as
long as someone who knows what they\'re doing is in overall charge.
I don\'t think there is much else I can do for you.

Yes, I have that impression.
In that case I won\'t bother responding to your other points except to
point
out that your schematics show AO6407 FETs, the data sheet for which is
trivial to find.
Under Absolute Maximum Ratings Vgs is listed as +/- 8V Maximum.
If you want intermittent failures after production has started, just hit
it
with 12V.

Ok, my bad. I thought I had checked that but I got something wrong. The
parts on the board are something else, these were picked for the
simulation
because they are in the LTspice library. I get tired of fighting the tool
to get third party models to work.
That\'s ok, I\'ve made worse design errors. I think resistors lower than 10K
and a circuit similar to the one on that web site will switch fast enough
if
you pay attention to resistor power dissipation and Vgs max. R14 and R15
may
not be needed or can be a lot lower than 10K. Try a simulation with 4.7K
and
100 ohms. You never did tell me what D3 is for. I haven\'t used 4000B logic
for um never mind how long. Is it still in production?

Element-14 in Australia (it used to be Farnell /Newark) has 306 different
parts in stock that fit CD40**. Everything in the first sheet is labelled a
\"best seller\", so it does seem to be still in production. Most if it will
probably go into legacy products, but I certainly ran into design problems
all though my career where logic that could run slowly from an up to 18V
supply was just the solution I needed. Unlike the 555 which seems to
persist because some designers are lazy and unimaginative, there weren\'t
any better alternatives.

Yes I agree it\'s useful if you want a slow (by today\'s standards) system
working directly on 12V or more. I managed never to design a 555 into
anything. I\'ve seen some strange circuits using a 555 including SMPS PWM
controller.

--
Bill Sloman, Sydney

 

[Rick C]

On Wednesday, December 2, 2020 at 10:39:20 PM UTC-5, Edward Rawde wrote:

\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2357c8a-f038-477a...@googlegroups.com...
On Wednesday, December 2, 2020 at 9:32:45 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:f9beb047-d324-4bbf...@googlegroups.com...
On Wednesday, December 2, 2020 at 7:09:55 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:7d3d16b5-aaef-49f9...@googlegroups.com...
On Wednesday, December 2, 2020 at 5:46:57 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e4285dd9-ed97-4189...@googlegroups.com...
On Wednesday, December 2, 2020 at 3:26:58 PM UTC-5, Edward Rawde
wrote:
\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde
wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it
gets
some
shoot through during the switching.
[...]
Having the team distributed around the world isn\'t necessarily an issue
as
long as someone who knows what they\'re doing is in overall charge.
I don\'t think there is much else I can do for you.

Yes, I have that impression.
In that case I won\'t bother responding to your other points except to
point
out that your schematics show AO6407 FETs, the data sheet for which is
trivial to find.
Under Absolute Maximum Ratings Vgs is listed as +/- 8V Maximum.
If you want intermittent failures after production has started, just hit
it
with 12V.

Ok, my bad. I thought I had checked that but I got something wrong. The
parts on the board are something else, these were picked for the simulation
because they are in the LTspice library. I get tired of fighting the tool
to get third party models to work.
That\'s ok, I\'ve made worse design errors. I think resistors lower than 10K
and a circuit similar to the one on that web site will switch fast enough if
you pay attention to resistor power dissipation and Vgs max. R14 and R15 may
not be needed or can be a lot lower than 10K. Try a simulation with 4.7K and
100 ohms. You never did tell me what D3 is for. I haven\'t used 4000B logic
for um never mind how long. Is it still in production?

D3 is to prevent the comparator from being damaged by reverse power. The guy designing this board added a part to protect everything from high voltage and reverse voltage. He never saw an LT part he didn\'t like and the rest of the board is already rated for +40 volts, just in case! So a simple diode should protect the comparator and everything else is good already I think.

What web site? The pages you\'ve pointed to don\'t actually give much information. They are very general.

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

 

[Rick C]

On Wednesday, December 2, 2020 at 10:48:03 PM UTC-5, Edward Rawde wrote:

jla...@highlandsniptechnology.com> wrote in message
news:u3ngsfhkn7u43qs1v...@4ax.com...
On Wed, 2 Dec 2020 17:12:04 -0500, \"Edward Rawde\"
inv...@invalid.invalid> wrote:

\"Edward Rawde\" <inv...@invalid.invalid> wrote in message
news:rq8q5r$l3r$1...@gioia.aioe.org...
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:6fce9360-b9e9-450f...@googlegroups.com...
On Wednesday, December 2, 2020 at 1:10:18 AM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:02352733-1a66-48f7...@googlegroups.com...
On Tuesday, December 1, 2020 at 9:56:01 PM UTC-5, Edward Rawde wrote:
\"Rick C\" <gnuarm.del...@gmail.com> wrote in message
news:e2a6129f-a999-4b9d...@googlegroups.com...
I have a circuit with a pair of pFETs to switch power and it gets
some
shoot through during the switching.

One further thought.
If the problem is what happens when both switches are on then control them
independently and arrange for that not to be the case.
In other words you need a break before make switchover.
Hang sufficient capacitance on the rail to the motor control circuit so it
doesn\'t see the join.


How about using two diodes? Too easy I guess.
Yes a couple of diodes producing Vmain would stop Vin and Vbatt ever meeting
each other.
Yes, they will do that. But they won\'t allow the rest of the circuit to work and the reason why has already been covered. It\'s also very obvious if you look at what the circuit is doing.

In fact, the diodes are already there for the low current always on path. They work like a champ!

Actually, the predecessor circuit to this one had a FET based diode pair to combine the input and battery circuits. But that was with a higher voltage input and now we are using a 12 volt input. Use diodes and the battery will always be powering the circuit until it runs down.

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209