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INA185: INA185 VS and VOUT design questions

Roy Chan
Expert 5840 points

Part Number: INA185

Hello Expert:

  We would like design INA185A4 version (Gain=200V/V) current sense AMP.

I found there have one case may exceed Vout max rating spec  as below desciption can you please help review and give the feedback suggestion? 

application case :

(1)VS connect to 3.3V,

(2) Iload max =22A 

(3) unidirectional applicaiton (VREF =0V).

(4) Rsense = 1mohm. 

Base on the Above applicaiton. the calculated result of Vout = 4.4V seems out of Vout max rating spec ( out of VS+0.3V = 3.3V +0.3V = 3.6V) 

is any risk of this design ? should I change connect to 5V for VS power supply ?  thank you 

image.png

 

  • +1
    TI__Mastermind 25855 points

    Roy, 

    The absolute maximum here more refers to external sources driving the VOUT pin into these types of voltages. The part itself is incapable of driving itself higher than VS, and in the scenario you describe the part would saturate against the rail, similar to any op amp. This is safe to do, but obviously the customer would not be able to measure any voltage higher than the saturation point. My recommendation would be to try and develop of a solution of the A3 GAIN and a slightly larger shunt to maximize the full scale range utilized while keeping the part within the linear operating range. Dont forget to take swing limitations into account. 

  • 0 in reply to Carolus Andrews
    TI__Expert 5840 points

    Hello Carolus:

    Thank you for your detail explanation

    Let me resolved the E2E thread 

    Roy