Guest
Hi,
I'm trying to design a power current source. It has to have some
features that make it a bit of a challange to design (for me at
least...)
it has to do the following:
- supply about 2-3 amps (no need for programmability, it can be preset
to a value when constructed).
- have a low minimum voltage drop, of 1 Volt or less (0.5V would be
better). That is, it should work even if Vcc=12V and the load needs 11V
to keep the preset current. of course, it should also work with a
higher Vcc.
- keep a reasonably constant current for both changes in the load, and
(the bigger problem) for a changing Vcc.
- the load is returned to ground, so the source has to be on the "high"
side.
- NO need for good precision, +/-5% is more than ok. the conditions are
DC so bandwidth isn't an issue as well.
it seems that each design I find or make meets only some of the
criteria above.
for example, an LM317 or similar regulator in a current loop would have
been fine, except the large minimum voltage drop (definitely not less
than 2 or even 3 volts).
am I requiring too much? help anyone?
thanks,
Guy.
I'm trying to design a power current source. It has to have some
features that make it a bit of a challange to design (for me at
least...)
it has to do the following:
- supply about 2-3 amps (no need for programmability, it can be preset
to a value when constructed).
- have a low minimum voltage drop, of 1 Volt or less (0.5V would be
better). That is, it should work even if Vcc=12V and the load needs 11V
to keep the preset current. of course, it should also work with a
higher Vcc.
- keep a reasonably constant current for both changes in the load, and
(the bigger problem) for a changing Vcc.
- the load is returned to ground, so the source has to be on the "high"
side.
- NO need for good precision, +/-5% is more than ok. the conditions are
DC so bandwidth isn't an issue as well.
it seems that each design I find or make meets only some of the
criteria above.
for example, an LM317 or similar regulator in a current loop would have
been fine, except the large minimum voltage drop (definitely not less
than 2 or even 3 volts).
am I requiring too much? help anyone?
thanks,
Guy.