OPA547: Two OPA547 shorted at their outputs

Wolfgang Schroeder3

Part Number: OPA547

I have two OPA547 used as non inverting Amps. Both are running different output voltages,
may be one at 30V the other one at 5V.Both are hardware current limited to ~80mA by a config. resistor of 270k.

In that case one is working as source, here the 30V Amp the other one as sink (5V) (I think)

Now I shortcut both outputs.

What happens ? The 30V opamp I think should go into current limit , and what about the 5V Opamp ?

The essential question is: will this kill one of the Opamps ?

over 7 years ago

0 kai klaas69 over 7 years ago

Guru 140200 points

Hi Wolfgang,

depending on which OPA547 goes earlier into current limitation, any voltage between the two output voltages can be seen. Keep in mind that the current limiting feature of OPA547 is not extremely precise but shows some manufacturing tolerances and also some drift.

wolfgang.TSC

Kai

0 Wolfgang Schroeder3 over 7 years ago in reply to kai klaas69

Prodigy 190 points

Hey Kai,

Thank you for the simulation. So it may happen that there begins a kind of oscillation.

Sure this is not a normal user situation but erroneously it may happen.

But you think that the sinking OP will not be killed ? Because I cannot find any
information in the datasheet about source or sink capability..

Thank you

Wolfgang

0 kai klaas69 over 7 years ago in reply to Wolfgang Schroeder3

Guru 140200 points

Hi Wolfgang,

the current limiting works for both polarities, in and out of the output of OPA547. You can see this from "+/-" sign in the specification on page 3 of datasheet:

"Current Limit Range: 0 to ±750 mA"

Kai

0 Wolfgang Schroeder3 over 7 years ago in reply to kai klaas69

Prodigy 190 points

hey Kai,

Thank you, that's what I was searching.

Best regards

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OPA547: Two OPA547 shorted at their outputs