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INA4181: Bandwidth choosing

Victoria Qin
Intellectual 1690 points
Part Number: INA4181

Hi experts,

Good day!

INAx181 family has different BW.

1. I would like to know the experience on how to choose enough BW device. 

2. Customer is evaluating it in micro inverter, the switching frequency is 120khz, how to choose enough BW device?

Thanks!

Victoria

  • 0
    TI__Mastermind 30360 points

    Hi Victoria,

    Depending on the location where measurement is taken, the requirement for the current sense amplifier can be quite different. I recommend customer make a plot of  the input common mode voltage and current to be measured. TINA simulation can be a great tool in helping with initial verification once operating conditions are defined. Please reach out if help is needed in this regard.

    I also recommend customer browse our video library and other documentation. Here is an e-book to start with.

    Regards, Guang

  • 0 in reply to Guang Zhou
    TI__Intellectual 1690 points

    Hi Guang,

    Thanks for learning materials which are useful to me! Customer is Hoymiles which is top2 micro solar inverter company in the world. Hoymiles is evaluating INA4181 in micro inverter. Common mode voltage range is 0~25V. Bi-di current is +-25A. Power supply is 3.3V. Could you help to evaluate the worst case current accuracy using INA4181A1? Customer's biggest concern is bandwidth not enough so that influences the current accuracy. 

    Thanks&BR

    Victoria

  • +1 in reply to Victoria Qin
    Guru 276380 points

    The bandwidth specification measures at which frequency a sine wave is attenuated by 3 dB; see figure 16:

    So even with the A1 device, a sine wave of 120 kHz would be attenuated a little bit. And if the current you want to measure is not a sine wave, you'd need even more bandwidth than that.

    It looks as if the INA4181 is not suitable.