OPA858-Q1: OPA858-Q1

deepthi kankanampati

Prodigy 40 points

Part Number: OPA858-Q1

Tool/software:

Subject: Clarification Needed on PDbar Pin Behavior at ±2.5V Supply

Hi everyone,

I am working with [OPA858-Q1] and have a question regarding the PDbar (Power Down) pin.

The datasheet mentions that for normal operation, the PDbar pin must be connected to the positive supply. However, under the "Power Down" section, the behavior at ±2.5V supply seems to differ.

What should the PDbar pin be connected to when operating at ±2.5V to enable the op-amp?
Could someone explain the reasoning behind this behavior?
will there be any change in voltage at input inverting terminal if we are giving PDbar to positive supply?

I appreciate any insights or references to clarify this.

Thank you!

16 days ago

0 Clemens Ladisch 16 days ago

Guru 286800 points

The behaviour does not differ. Please explain what exactly seems to be different.

1. +2.5 V

2. High = enabled, low = powered down.

3. No (except when there are feedback resistors connecting it to the output).

0 deepthi kankanampati 16 days ago in reply to Clemens Ladisch

Prodigy 40 points

in 3rd point when there is feedback resistor connecting output to input , how will it change the voltage at inverting input pin of opamp by changing PDbar pin voltage ?

0 Clemens Ladisch 15 days ago in reply to deepthi kankanampati

Guru 286800 points

When the /PD pin is low, the output is disabled, so no current flows through the feedback resistors. (But the resistors still connect the input to the output load.)

0 Ignacio Vazquez Lam1 15 days ago in reply to deepthi kankanampati

TI__Genius 11615 points

Hi Deepthi,

Clemens is correct, you will not see any voltage changes at the input nodes due to powering the PD pin when enabling the device.

Best Regards,

Ignacio

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OPA858-Q1: OPA858-Q1