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OpAmp to provide -15V from -38V <100ma

Question asked by K1MGY on Dec 15, 2015
Latest reply on Dec 15, 2015 by K1MGY

I have two problems to solve and hopefully this can be done with a single (dual) part.

 

1. Supply a "clean" -15 V at about 35ma to a transimpedance amplifier from a -38V source,

 

2. Provide a steady-state -38V and (2) a timed sweep from 0V to around -5V.  Here, nanoamperes of current are involved.

 

I considered an LDO for -15, but those I can find won't take the -38V presently coming from a converter and we don't want to create another noisy switching converter!

 

So I'm thinking a "high output current" amplifier (dual package) powered by our available -38V (with the + rail of the amplifier to system ground) would be an option.  One of these would produce the -15V based on bias at the inverting input, and the other driving the -38V rail with a mosfet-selected triangle generator for the timed sweep.

 

Does Analog Devices have a suitable part for this idea.. or other ideas that will give us these voltages?

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