INA241A: Frequency compensation

LIU QINGFENG

Part Number: INA241A
Other Parts Discussed in Thread: OPA388,

Tool/software:

Dear Supporter:

We are trying to use this chip to sample current (range +/- 100A ) in high side with ~5V common voltage.

However we are not able do frequency compensation by parallel capacitors with gain resistors, as the resistors to set the gain are embedded inside the chip, which we have practiced in other amps such as OPA388.

we have tried to add filter in the front but result is not very good as previous pracitice.

Any suggestion？

Regards// Qingfeng

1 month ago

0 Javier Contreras4 1 month ago

TI__Mastermind 32290 points

Hello Liu,

This is not like an amplifier and cannot add external components in the feedback loop. What exactly are you attempting to fix? What is the input you expect and output you expect and how does the INA241A differ?

By frequency compensation are you having issues with stability? If this is the case what is the output you are driving? It there a large capacitor (>1nF) at the output? If this is inductance in the Rshunt and large spikes in current please see this post: https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1472101/ina241b-current-sensing-wrong

Regards,

Javier

0 LIU QINGFENG 1 month ago in reply to Javier Contreras4

Prodigy 70 points

Javier：

Below is the schematic, the output is to driver the ADC of one DSP, with additional RC filter ; we found the ADC sensed the ~2KHz ripple which are not expected.

above post makes sense and we will try ...thanks.

+1 Javier Contreras4 1 month ago in reply to LIU QINGFENG

TI__Mastermind 32290 points

Hello Liu,

Please measure REF2 and REF1. The input impedance changes with input voltage by some ~10µA so you can see 100µV of error at the output normally since the Vref is driven through 10Ω. Please verify the VREF voltage is not changing. Everything else looks fine.

Regards,

Javier

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INA241A: Frequency compensation