OPA462: OPA462IDDAR, start-up voltages

Lucio Orsini

Part Number: OPA462

Hello

We provide a differential voltage power supply, powering the OPA462

I noticed, on start-up, the negative voltage V- arrives before the positive V+.

On the positive power supply we have a little undershoot of -1.4V, while the negative power supply has already reached the -4V.
So V+ > V-.

But, if i consider E/D comm connected to GND, this pin has 1.4V above the V+ during the undershoot.

Can this cause a failure of the device in long term usage?

Thank you

over 2 years ago

0 kai klaas69 over 2 years ago

Guru 140200 points

Hi Lucio,

yes, this can cause latch-up and should be avoided in any case!

Mount latch-up protection Schottky diodes from each supply line to power ground as discussed in this thread:

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/957524/opa2990-about-powerup-sequence

Kai

0 Thomas Kuehl over 2 years ago

TI__Guru* 93105 points

Hi Lucio,

Kai provides a good solution for protecting the OPA462 from dual power supply, out-of-sync start-up conditions. You don't mention what the OPA462 maximum V+/V- supply levels will be so do take that into account when selecting the supply protection diodes.

Schottky diodes tend to be lower voltage diodes with reverse breakdown voltages commonly of 30 V or 50 V. The OPA462 is usable with supplies up to +/-90 V, or +180 V, etc. Therefore, for higher voltage OPA462 supplies a rectifier diode such as the 1N5402 (200 V) or 1N5403 (300 V), or a high voltage, unipolar transient voltage suppressor (TVS) diode would be appropriate for the application.

Regards, Thomas

Precision Amplifiers Applications Engineering

0 kai klaas69 over 2 years ago in reply to Thomas Kuehl

Guru 140200 points

Hi Thomas,

Thomas Kuehl said:
Schottky diodes tend to be lower voltage diodes with reverse breakdown voltages commonly of 30 V or 50 V. The OPA462 is usable with supplies up to +/-90 V, or +180 V, etc.

This is a good point. I often use the SB3100.

Kai

0 Lucio Orsini over 2 years ago in reply to Thomas Kuehl

Prodigy 10 points

Thank you for the answers.

Amplifiers

Amplifiers forum

OPA462: OPA462IDDAR, start-up voltages