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.
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.
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.
Normally the E/S pin on the OPA548 should allow you to disable it.
Devil_H@ck said:
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.
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