CD4000 models - earthed pins

[The Captain]

Does anyone know how to handle pins in a PSpice A/D circuit using
CD4000 series IC models.

My specific problem is with the CD4013 dual D type flip flop connected
as a divide by two circuit. I am using + and - 5V supplies, specified
in param as CD4000_VSS = -5V and CD4000_VDD = +10V. However, the S
and R pins need to be connected to circuit earth or equivalent, which,
in this case, is the -5V VSS level, as specified in param.

How do I go about making this connection? I've tried connecting the S
and R pins to a -5V VDC voltage source, but this simply doesn't work -
Q output is near zero volts for all CK inputs.

I'd appreciate any help, as this is holding up a fairly important
project and it's an awkward thing to have to explain to investors!

Regards

John Fortier

 

[Tim Stinchcombe]

Does anyone know how to handle pins in a PSpice A/D circuit using
CD4000 series IC models.

My specific problem is with the CD4013 dual D type flip flop connected
as a divide by two circuit. I am using + and - 5V supplies, specified
in param as CD4000_VSS = -5V and CD4000_VDD = +10V. However, the S
and R pins need to be connected to circuit earth or equivalent, which,
in this case, is the -5V VSS level, as specified in param.

How do I go about making this connection? I've tried connecting the S
and R pins to a -5V VDC voltage source, but this simply doesn't work -
Q output is near zero volts for all CK inputs.

I'm not a Pspice user, but a quick look at the Reference and User guides
suggests it is not that far removed from Xspice, at least in some of the
concepts. The S and R pins will almost certainly be 'digital', and as such
you will need to connect them either to a 'digital ground', or 'digital
power' - connecting them to analogue nodes (either normal ground or a power
source) will probably make the simulator automatically introduce special
a-to-d or d-to-a blocks in order to convert them, but whether they come out
as 'low' or 'high' could be hit or miss (and will depend on the 'I/O model'
referenced in the CD4013 model, apparently called 'IO_4000B', which likely
'defines' the transition levels from low to high etc.). Find the appropriate
D_GND or D_PWR symbols (or whatever they are called), and hook them in
instead. This will also apply to the Vdd and Vss - the CD4013 model says
they are optional, so if I were you I'd leave them out to see if it works
with out them first!

Hope that might be of some use.... (there are several sections in the User
Guide about digital and mixed analog/digital simulation, but they are hardly
a quick read!)

Tim
--
__________________________________________________________
Tim Stinchcombe

Cheltenham, Glos, UK

 

[Tim Stinchcombe]

Ah ha...

My specific problem is with the CD4013 dual D type flip flop connected
as a divide by two circuit. I am using + and - 5V supplies, specified
in param as CD4000_VSS = -5V and CD4000_VDD = +10V. However, the S
and R pins need to be connected to circuit earth or equivalent, which,
in this case, is the -5V VSS level, as specified in param.

....I now see where this is coming from - the 'Creating Custom Digital Power
Supplies' section in the User Guide? (I didn't immediately see where the
'odd' arithmetic with Vdd came from!) So R and S still need to be connected
to digital nodes, but you'll have to make sure that you reset all the params
properly so that all CD4000 chips 'see' the modified power supply (there
appear to be quite a few things to consider which I can't comment on due to
not being a Pspice user). It might be a good idea to see if you can get your
circuit working with 0 - 5V supplies first perhaps, _then_ try modifying to
+/-5V?

Tim
--
__________________________________________________________
Tim Stinchcombe

Cheltenham, Glos, UK

 

[Jim Thompson]

On 17 Jul 2003 15:03:02 -0700, Captain794@yahoo.com (The Captain)
wrote:

Thanks, Tim,

The CD4000 power supplies, if they are not the nominal +5V and digital
earth, are specified in a parameter block which is inserted onto he
same page as the CD4000 model. For + and - 5V supplies, which I am
fairly well constrained to using since this is a telecom circuit
working from + and - 5 volt supplies and the inputs and outputs of the
CMOS portions of the circuit have to conform to the balanced power and
signal requirements of the rest of the circuit, the VSS pins are set
to -5V while the VDD pins are set to +10V, that is ten volts above the
reference VSS, giving a 5 V power supply when referenced to the circut
earth.

What I need is a means of connecting the R and S pins to VSS. So if
there any PSpice gurus out there who can tell me how to do this, I'd
appreciate it.

[snip]

There is apparently a way to configure a CD4000 Power Block for what
you need, but since I haven't used a CD4000 since I was a kid ;-) I'd
just build ideal EVALUE interfaces into and out of the CD4000.

For example

Einto4000 node1 0 Value {V(%IN+,%IN-)/2-2.5}

Eoutof4000 node2 0 Value {V(%IN+,%IN-)*2-5}

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| Jim-T@analog_innovations.com Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

For proper E-mail replies SWAP "-" and "_"

Get Lolita Out of Debt... Add Three Inches to Your Mortgage!

 

[The Captain]

Charles Edmondson <edmondson.ns@ieee.nw.org.invalid> wrote in message news:<3F1808C9.9000105@ieee.nw.org.invalid>...

Since we're top posting!

What you need to do is use a net name of whatever you specified for the
ground and power nodes in your CD4000 power supply to attach to your
pins. In Capture, you can just use net aliases to provide the
connectivity. In Schematics, just use a bubble and name it to that node.

You did use UNIQUE names for these nodes, and not the defaults, didn't
you!

Also, be sure how you specified the voltages. I was a little confused
in your descriptions, because you kept using +10 when your supplies are
+/-5. Often those voltage specifications are not relative, but absolute.

Charlie
Edmondson Engineering
Unique Solutions to Unusual Problems
Whatever doesn't kill us, makes us sore...

The Captain wrote:

Thanks, Tim,

The CD4000 power supplies, if they are not the nominal +5V and digital
earth, are specified in a parameter block which is inserted onto he
same page as the CD4000 model. For + and - 5V supplies, which I am
fairly well constrained to using since this is a telecom circuit
working from + and - 5 volt supplies and the inputs and outputs of the
CMOS portions of the circuit have to conform to the balanced power and
signal requirements of the rest of the circuit, the VSS pins are set
to -5V while the VDD pins are set to +10V, that is ten volts above the
reference VSS, giving a 5 V power supply when referenced to the circut
earth.

What I need is a means of connecting the R and S pins to VSS. So if
there any PSpice gurus out there who can tell me how to do this, I'd
appreciate it.

"Tim Stinchcombe" <timng1@tstinchcombe.freeserve.co.uk> wrote in message news:<bf6rdv$3bu$1@newsg4.svr.pol.co.uk>...


Does anyone know how to handle pins in a PSpice A/D circuit using
CD4000 series IC models.

My specific problem is with the CD4013 dual D type flip flop connected
as a divide by two circuit. I am using + and - 5V supplies, specified
in param as CD4000_VSS = -5V and CD4000_VDD = +10V. However, the S
and R pins need to be connected to circuit earth or equivalent, which,
in this case, is the -5V VSS level, as specified in param.

How do I go about making this connection? I've tried connecting the S
and R pins to a -5V VDC voltage source, but this simply doesn't work -
Q output is near zero volts for all CK inputs.


I'm not a Pspice user, but a quick look at the Reference and User guides
suggests it is not that far removed from Xspice, at least in some of the
concepts. The S and R pins will almost certainly be 'digital', and as such
you will need to connect them either to a 'digital ground', or 'digital
power' - connecting them to analogue nodes (either normal ground or a power
source) will probably make the simulator automatically introduce special
a-to-d or d-to-a blocks in order to convert them, but whether they come out
as 'low' or 'high' could be hit or miss (and will depend on the 'I/O model'
referenced in the CD4013 model, apparently called 'IO_4000B', which likely
'defines' the transition levels from low to high etc.). Find the appropriate
D_GND or D_PWR symbols (or whatever they are called), and hook them in
instead. This will also apply to the Vdd and Vss - the CD4013 model says
they are optional, so if I were you I'd leave them out to see if it works
with out them first!

Hope that might be of some use.... (there are several sections in the User
Guide about digital and mixed analog/digital simulation, but they are hardly
a quick read!)

Tim

Thanks, everyone. The problem is now solved.

John