INA225-Q1: Output Oscillates, What could be the reason?

vijay kumar thimmaiah

Prodigy 60 points

Part Number: INA225-Q1

Output of the Amplifier oscillates independent of the gain and output load (resistive load).

Shunt: 1mOhm

Gain: 100

What could be the reason?

Output Waveform and Schematic attached.

over 8 years ago

0 Peter Iliya over 8 years ago

TI__Mastermind 32395 points

Dear Vijay,

We are looking at this now and will reply back shortly.

Sincerely,
Peter Iliya
Current Sense Applications

0 Peter Iliya over 8 years ago in reply to Peter Iliya

TI__Mastermind 32395 points

Hello Vijay,

Other than the resistive load, is there any else the INA225-Q1 is driving (ADC, capacitive load)? If so, could you measure the output then?

What does the input signal look like?

Peter Iliya

0 vijay kumar thimmaiah over 8 years ago in reply to Peter Iliya

Prodigy 60 points

Hello Peter,

The problem was found. It was the output capacitor at the connector (ESD Capacitor, Intended for ESD Protection).

For INA225-Q1, Maximum allowed output capacitor is 1nF. The Amplifier oscillates for capacitance > 1nF.

Regards

Vijay

0 Peter Iliya over 8 years ago in reply to vijay kumar thimmaiah

TI__Mastermind 32395 points

Thanks Vijay for letting us know.

Please post to forum if you have more questions.

Peter Iliya
Current Sense Applications

0 Jason Bridgmon over 8 years ago in reply to Peter Iliya

TI__Genius 14825 points

Vijay,

For additional information on output filtering using RC circuits while maintaining stability, please see our app note Closed-Loop Analysis of Load-Induced Amplifier Stability Issues Using Zout. I hope that helps as well.

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INA225-Q1: Output Oscillates, What could be the reason?