Hi - my first post here!
I am building a one-off project that requires hundreds of analogue outputs capable of swinging 0-50V and source / sink about 15mA into a resistance bridge. My dilemma is to choose the simplest & cheapest output buffer that will do the job reliably with low component count, as it is to be repeated hundreds of times.
The signal starts out as 0-5V with a freq. range of DC - 100 Hz. DC accuracy is moderately important. The output buffer stage needs to apply a gain of 10 and deliver the output current into a load that is basically resistive around the 4k mark, but the far end of it could be anywhere between 0 and 50V as the load is in a bridge configuration. I can make up any supply rails that are needed for the job. If the amp doesn't go rail-rail then we can provide say -5V and 55V easily.
Choices as usual are:
1. Build discrete amp
2. Use ordinary op-amp with bootstrapped supplies
3. Use power op-amp
Option 1 gives me a headache with the component count, as does 2 to a lesser extent. Trouble with 2 is the gain - I can't have all the gain in the bootstrapped stage because the input CM range would go outside the moving rails. So I need another stage which is a nuisance.
Option 3 - I could be lazy and fall back on the good old LM675. But it's an expensive overkill. I don't need 4 amps and don't want >1W per device of quiescent dissipation when there are 64 on each driver board.
So - the question - is there a magic bullet device that gives me the 15mA or so of current required, that comes in at a price more typical of an ordinary op-amp? Or a circuit dodge?
Thanks
>V<
I am building a one-off project that requires hundreds of analogue outputs capable of swinging 0-50V and source / sink about 15mA into a resistance bridge. My dilemma is to choose the simplest & cheapest output buffer that will do the job reliably with low component count, as it is to be repeated hundreds of times.
The signal starts out as 0-5V with a freq. range of DC - 100 Hz. DC accuracy is moderately important. The output buffer stage needs to apply a gain of 10 and deliver the output current into a load that is basically resistive around the 4k mark, but the far end of it could be anywhere between 0 and 50V as the load is in a bridge configuration. I can make up any supply rails that are needed for the job. If the amp doesn't go rail-rail then we can provide say -5V and 55V easily.
Choices as usual are:
1. Build discrete amp
2. Use ordinary op-amp with bootstrapped supplies
3. Use power op-amp
Option 1 gives me a headache with the component count, as does 2 to a lesser extent. Trouble with 2 is the gain - I can't have all the gain in the bootstrapped stage because the input CM range would go outside the moving rails. So I need another stage which is a nuisance.
Option 3 - I could be lazy and fall back on the good old LM675. But it's an expensive overkill. I don't need 4 amps and don't want >1W per device of quiescent dissipation when there are 64 on each driver board.
So - the question - is there a magic bullet device that gives me the 15mA or so of current required, that comes in at a price more typical of an ordinary op-amp? Or a circuit dodge?
Thanks
>V<
