INA169: Asking for the INA169 current sensing schematic review

Part Number: INA169

Hi Team,
Would you please help provide your comment for the INA16 schemtic review.
The common mode is from 5V ~20V. Max current is 5A.
here is the schematic.
https://txn.box.com/v/ina

previous discusstion mail thread

e2e.ti.com/.../760006


BR,
SHH

1 Reply

  • Hello SHH,

    I do have a couple comments. Why is the 30-V voltage detector (U5301) necessary? You have this sensing the output and it seems to be there to alert the host processsor if there is a over-current protection (OCP) event. This seems to mean that if VOUT of INA169 exceeds 30 Volts, then U5301 will alert the processor, but this simply cannot happen. The INA169 is powered with a 5-V rail and thus its ouput can't exceed {5V-0.7V-(Vsense)}.

    Additionally, during normal conditions the voltage detector on the output is going to increase current measurement error. The device is specified with an operating current of 3µA to 8µA. With your circuit when the source current (Is) is 5.5A, the IOUT current of INA169 is:
    IOUT = Is*Rs/1kΩ = 5.5A*0.01Ω/1kΩ = 55µA.

    This means the voltage detector's operating current will divert current aways from the output current and directly add anywhere from 5.45% to 14.54% error when measuring 5.5A.

    Hope this helps.
    Sincerely,
    Peter Iliya
    Current Sensing Applications