OPA2325: Diode clamp for VCC

Beida Song

Part Number: OPA2325
Other Parts Discussed in Thread: OPA2335, ESD441,

Tool/software:

Hi Expert,

Customer add diode to clamp between VCC and GND. But with the temperature rise to +60C from 25C, the output is nonlinear. After removing the diode, the output is liner.

We think the leakage current increase with the temperature rise.

When there is no diode as clamp, whether there is clamp diode in internal part of OPA2335?
Except the diode, there is better clamp components or method?

Customer's schematic as below:

Thanks in advance.

6 months ago

0 Beida Song 6 months ago

TI__Prodigy 590 points

Relationship between Diode reverse current and temperature.

0 Clemens Ladisch 6 months ago in reply to Beida Song

Guru 308120 points

The OPA2335 has internal clamping diodes that are optimized for low leakage currents. (But they burn out at 10 mA.)

Choose some other diode. (Even the 1N4148 would have lower leakage.)
ESD/TVS diodes might work better (e.g., the ESD441 has a typical leakage current of 1.2 nA at 150 °C).

0 Ron Michallick 6 months ago in reply to Clemens Ladisch

TI__Guru**** 159961 points

Beida,

Like Clemens said, use low leak diodes or no diodes. OPA2325 has phase reversal protection making the diodes unnecessary.

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OPA2325: Diode clamp for VCC