my own pga2310 pre-amp :)

[kafka]

I have a problem with shut down in OPA548. It works as -15V supply. I take 2.5V reference from TL431 and OPA inverts it with gain = 6. It works good. But I can't shut it down. I used the circut from the datasheet with dual supply mode. The e/s pin is at the same potentian as negative rail, so it should be good, but output voltage changes then from -15 to -12 and I can give quite a lot currnet.

And another question. How can I shut down reg1117(3,3V)? Any idea? I feed it from 5V regulator which is enable all the time.

 

[Devil_H@ck]

You could use a MOSFET to cut the power to the REG1117.
Normally the E/S pin on the OPA548 should allow you to disable it.

 

[kafka]

Normally the E/S pin on the OPA548 should allow you to disable it.

I know it should, but it don't. The rest of OPA548 works well, but they have negative rail tight GND and I can drive them from TTL levels. That one have positive rail at GND level and negative at -18V.