Re: Reversed Biased MOSFETS & BJT's?

"legg" <legg@[EMAIL PROTECTED]
> wrote in message 
news:l324f45c5rc2cj13qsc5948sa0o82dokfb@[EMAIL PROTECTED]
>
> Reverse battery protection at he output of a circuit is the same as
> for the input. Googling should provide various suggestions.
>
> RL

For discharge I was planning to have a NPN transistor with a current sense

resistor going to ground.  Then apply some base current to get my
programmed 
discharge current to flow.  Perhaps I need the current sense resistor on
the 
collector so I don't have to figure in base current.  If I need to, I
could 
add in a Schottky diode to prevent current flow in a reverse polarity 
situation.  But if I don't need the diode, I would prefer not to have the 
drop in situations of discharging a single 1.2V cell.

For the charge side, if I have the battery grounded through a current
sense 
resistor, and the switch on the high side, then a properly connected
battery 
would have Vplus - Vbatt across the collector to emitter.  A reversed 
battery would have Vplus + Vbatt across the transistor.  I thinking a PNP 
common emitter or P channel transistor with base or gate pulled high and 
switched lower to turn ON.  Seems like the charge side would be correctly 
biased and I would just need to use a transistor rated for supply voltage
+ 
battery voltage.

Does this sound right or is there a better way?

Thanks!
RogerN