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INA333: specs

J-ZHOU8
Expert 3010 points

Part Number: INA333
Other Parts Discussed in Thread: INA326,

Hi experts

My customer was looking for a replacement for the INA326.
When using the INA326, the output would occasionally experience latch-up (getting stuck at +5V) during power-up, possibly due to the steep rise of the power supply (+5V). Therefore, they were searching for a different amplifier.
The INA333 seemed suitable, and I was able to implement it by changing the peripheral resistors and capacitors without modifying the PCB pattern.
The results were positive, with no latch-up occurring.
We believe the INA333 is a valid candidate, is this correct?

 

Regards,

Zhou

  • 0
    TI__Mastermind 29760 points

    Hi Zhou,

    Was the INA326 being used in already existing designs? 

    These instrumentation amplifiers have different architectures with the INA326 being current feedback while the INA333 being the more classic voltage feedback design. 

    That said, if this is working in your system then the INA333 would likely be a great fit. Just make sure that VREF is going to a low impedance voltage source as to not create any error in the internal reference voltage network.

    Best Regards,

    Robert Clifton 

  • 0 in reply to Robert Clifton56
    TI__Expert 3010 points

    Hi Robert

    Thank you for your reply.

    The circuit using the INA333 follows the connection example described in its datasheet (with Vref connected to GND), so we believe there are no issues with the design.

    There have been several other posts regarding latch-up issues with the INA326 during power-up.

    In our case, we confirmed that the device operates without latching up by slightly slowing down the power supply rise time. Consequently, if we use the INA326 in the future, we plan to design the circuit to ensure a slower power-on ramp-up. For our future reference, we would appreciate any advice or further insights you might have regarding this matter.

    Hope you can give us some comment.

    Regards,

    Jieyu

  • 0 in reply to J-ZHOU8
    TI__Mastermind 29760 points

    Hi Jieyu,

    Can you share the power supply ramp to the INA326 that causes latch-up and another one that doesn't? 

    Best Regards,

    Robert Clifton 

  • 0 in reply to Robert Clifton56
    TI__Expert 3010 points

    Hi Robert

    With the INA326, a power supply ramp waveform that rises from 0V to 4V in approximately 300μs to 400μs triggers a latch-up.
    On the other hand, a ramp waveform that takes about 40ms to reach 4V does not cause this issue.
    Although customer only have a power supply fixed at 40ms and cannot adjust the rise time in millisecond increments, it appears that such a long duration is not actually required.
    Notably, with the INA333, latch-up did not occur with either of these power supply ramps

    Regards,

    Zhou

  • 0 in reply to J-ZHOU8
    TI__Mastermind 29760 points

    Hi Jieyu,

    Sorry for the delay.

    As long as INA333 is verified to work, I don't see much design risk. 

    Thank you for sharing the latch-up behavior. This is an interesting behavior that you all have captured. I'll see if I can recreate in my lab.

    Either way do you need any additional help from our side? 

    Best Regards,

    Robert Clifton