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INA301: best option for current sensing

Giulio Zoppi
Intellectual 645 points
Part Number: INA301
Other Parts Discussed in Thread: INA225

Hello,

I am involved in the design of a series of power management supply (1.0V @ about  20A) for a digital processor.

We need fast telemetry, so we are exploiting our MCU's internal ADC. For the CS we were initially focused on INA301, but the best option would be a device with a configurable gain with a bigger gain capability in order to minimize voltage overshoot during the biggest current variation.

I need your valuable support in order to spot the right PN and maybe, if the best solution were an opamp with external components, the right configuration and some suggestion for the optimal layout.

Best regards,

GZ 

  • 0
    Guru 140200 points

    Ciao Giulio,

    is your current sensing shunt high side or low side? If it is high side then you really should take one of TI's INAs because of their awesome common mode rejection. The INA301A3, for instance, offers a common mode rejection of 120dB typically. A discrete OPAmp circuit with +/-0.1% resistors, on the other hand, will give less than 60dB common mode rection!!

    Kai

  • 0 in reply to kai klaas69
    Intellectual 645 points

    yes, definitely an high side sensing.

    We need to sense 1V with the best obtainable  performances in terms of accuracy, bandwidth with the lowest possible undershoot.

    what couple RS+CS do you suggest as a tradeoff?

    Do you have any design reference on the matter? ( we need suggestions for the layout).

    thanks a lot.

    G.

  • 0 in reply to Giulio Zoppi
    TI__Mastermind 34260 points

    Hi Giulio,

    Please look into INA225, with 4 gains to choose from - 25, 50, 100 and 200. Looks to me INA225 fits your application pretty well.

    Regards, Guang