OPA192: ouput protection concerns

Rock Su

Intellectual 2220 points

Part Number: OPA192
Other Parts Discussed in Thread: TVS1400

Hi Colleague,

In our customer current scenario, there will be a 14V in OPA192 output in some special time.

So the customer wants to confirm:

1. Whether OPA192 will be damaged?

2. If OPA192 will be damaged, how to add a protection circuit to protect?

3. If we could add a protection circuit, how fast does the protection need to be?

Thanks a lot!

over 3 years ago

0 Raymond Zhang1 over 3 years ago

TI__Mastermind 47486 points

Hi Rock,

1. Whether OPA192 will be damaged?

2. If OPA192 will be damaged, how to add a protection circuit to protect?

This is a compartor circuit with the Op Amp worked as comparator. Since V+ < V-, the output voltage should be close to -15V. The output is within the absolute Max. rating, and the part should not get damaged.

If you are concerned about the output, then you may lower the voltage rails to +/-5V (if you can) or +/-10 to 12V.

I normally do not use op amp as comparator, though the slew rate of OPA192 is relative high at 20V/usec. If you want to compare the two voltages, I would simply select a comparator instead. Also, OPA192 is a RRIO on the output, so your output will be either close to +15V or -15V depending on the input voltage comparisons.

3. If we could add a protection circuit, how fast does the protection need to be?

OPA192 has an adequate input circuit protection. If you concerned about the output protection, you can lower your voltage rails as stated above.

If you concerned about the transient voltage from elsewhere to the output pin of OPA192, then you may add zener or TVS to limit the output voltage transient conditions.

Best,

Raymond

0 kai klaas69 over 3 years ago

Guru 140200 points

Hi Rock,

where does the 14V come from?

Kai

0 Raymond Zhang1 over 3 years ago in reply to kai klaas69

TI__Mastermind 47486 points

Hi Rock,

I may be misunderstood the inquiry. I assumed that output pin may be momentarily in contact with 14V power source.

If OPA192's is shorted at the output with 14V, OPA192's short circuit protection will kick in and shall limit the power supply current at approx. 65mA, see the attached simulation.

1. Whether OPA192 will be damaged?

OPA192 will not be damaged (also see the absolute max. ratings table in section 6.1, which output short circuit is rated continuous).

2. If OPA192 will be damaged, how to add a protection circuit to protect?

The question I have is that what type of power source is 14Vdc. such as a switching power supply or 14V associated with inductance along the power source. If the 14V is associated with an inductance, then Ldi/dt = L* 65mA/dt could potential exceed 14V at OPA192's output in transient conditions (depending how fast dt is. Faster the dt, the higher the transient voltage spikes will be).