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INA190: Hi Kindly provide the review comments of the current sense amplifier

Aswin S Dharman
Prodigy 150 points
Other Parts Discussed in Thread: INA190

Hi Team,

Here Iam using this amplifier to sense the 4-20mA current and to give to the ADC to monitor 

  • 0
    Guru 140200 points

    Hi Aswin,

    isn't the schematic incomplete? What shunt do you use to convert the 4...20mA current into a voltage? And what about "R155"? Shall this be part of the charge bucket filter for the ADC input?

    Also, there should not be a resistor (R31) between the supply voltage decoupling cap "C20" and the supply voltage pin "VS" of INA190.

    Kai

  • 0 in reply to kai klaas69
    Prodigy 150 points

    Yea there is a shunt resistor is there between the two signals(5.1Ohm)

    And the R155 is given as an option to connect directly with the MCU ADC. Now we are using external ADC.

  • 0
    TI__Expert 5970 points

    Aswin,

    As Kai said you will want to remove R155, as it could create some inductance between the decoupling capacitor and the device even when populated with a 0Ω resistor. There shouldn't ever be a need for a resistor here anyways, so I would remove it.

    With the shunt resistor you mentioned, an input of 4-20mA will result in a nominal output of 510mV-2.55V. If the shunt resistor is not close to the input, be sure to run the inputs symmetrically during layout.

    As you're driving an ADC, the limited bandwidth of the current sense amplifier may require the use of a charge bucket in order to drive the ADC properly. This Document goes into detail as to why the problem occurs and how to design your amplifier so it can drive your ADC.

    Let me know if you have any more questions,

    Levi DeVries