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INA190: Maximum current (Imax) capacity of INA190

Nidhi P Shetty
Intellectual 735 points
Part Number: INA190
Other Parts Discussed in Thread: INA226, PGA281

Hello

I'm using current sense amplifier to detect the speaker failure in my project. I have chosen INA190 as current sense amplifier wherein my design constraints are

Vvs =3.3V , Vcm = 12V , Imin = 1uA , Imax =2A(4W speaker with 3 ohm impedance gives 1.333A) , Gain = 500V/V , Vref =0 , Current in sleep mode less than 1uA.

1) Whether INA190 is suitable for all my design constraints?

2) What is the maximum current Imax that I can consider which is supported by INA190.

3) Whether error of 0.3% is acceptable if the output of this is to drive an ADC.

Please help me out in this concern.

Regards

Nidhi P Shetty

  • 0
    TI__Mastermind 32395 points
    Hello Nidhi,

    Thanks for posting to the forum.

    The INA190A5 can satisfy most of these constraints except for measuring the entire dynamic range of 1uA to 2A which is 2/10^(-6) = 2 million-to-one. The greatest dynamic range you can achieve with INA190 is limited by the maximum swing-to-the-voltage supply rail (VSP_max) and maximum zero-current output voltage (VZL_max). You can gather these values from datasheet, but for the INA190A5 the greatest dynamic range you can achieve over temperature is VSP_max/VZL_max = (Vs - 40mV)/9mV. At Vs = 3.3V the dynamic range possible will be 362-to-1. This is much smaller than the dynamic range you are measuring. You can achieve a much greater dynamic range if you use a lower gain part and maximize the voltage supply rail to 5.5V. For example for the INA190A3 (gain 100V/V), dynamic range would be (5.5V - 40mV)/3mV = 1820-to-1. If you want to increase your range further you will have to consider using multiple amplifiers or implementing a way to switch in multiple shunt resistors for same amplifier. The INA226 can achieve a larger dynamic range (16 bits) only limited by its input offset of 10uV max. Additionally, you could look into using a transimpedance amplifier or even programmable-gain amplifier (PGA) where you could change the gain in order to accommodate the dynamic range. This app note covers how to use the PGA281.
    www.ti.com/.../tidu033.pdf

    Note in calculations above I am using the maximum spec values which are essentially guaranteed over temperature. If your product/device is used in typical, less extreme environments then you could expect the dynamic range to be limited by the typical specification values.

    There is no maximum current Imax for INA190 or for any current sense amplifier. The only real limitation is power dissipation capable of your shunt resistor and layout.

    Hope this helps.

    Sincerely,
    Peter Iliya
    Current Sensing Applications