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INA201: about INA201 output issue

Part Number: INA201
Other Parts Discussed in Thread: INA301, INA202

dear supporting team,

my customer is using INA201 in overflow protection circuit, the Rs is 0.67mOhm, and the overflow current threshold is 25A.  the sch is as below, they want to know which spec of INA201 cause the issue and how to solve it.

R92 & R93 =100 Ohm,C77 1000pf,R88 5.11k,R89   2.26k,

they found some INA201 sample will has mis-trigger when there is no loading(no input current), i.e. PIN3 will have higher than 0.6V voltage when there is no input.  and also could not recover.  the plot is as below:

failed chip: PIN3 output  (purple curve)

normal one:

if remove R89, test PIN2 output when first powering up, when there is no current input, Vcm=5.6V,  the waveform is as below:

yellow curve:power module output voltage,  green curve:normal ina201 PIN2,purple curve4.5v power supply of INA201,The blue curve is  the failed chip PIN2.

if shut down the module, they will find during the power module output voltage decreasing (no current at Rs), OUT voltage will increase, and for normal chip and failed chip, the have big difference, so which character cause the difference? and how to revise their circuit to handle the problem?

yellow: output voltage of the module.  green: pin2 of INA201.  purple: power supply of INA201

failed chip:

normal chip:

tks a lot!

  • Hi Vera,

    With 0A you are operating on the Vsense<20mV region. You can expect up to 1V in the output. Please refer to the Electrical Characteristic table and Page 15-17 in the application section of the datasheet. 

    What is the Vcm of this application? If the Vcm is less than 36V you could recommend INA301 to the customer. 


  • hi Mayrim,

    thank you for the answer!

    yes, understand that in Vcm<20mV region, the precision of INA201 will get worse.

    their Vcm is 5.6V.   

     during powering up and powering down, the chip will have the stage of  0V input.  so there will always be typical 300mV output,  what's the maximum value for INA201?  If it is 1V, then customer can not use it in such kind of scenario.

    for INA301, because the logic is reversed with 201, and also customer is using SOIC package for 201 now, so they can not do drop in replacement. 

    tks a lot!

  • Dear Vera,

    Unfortunately we do not spec a maximum for this range of the part. We took it to the bench and ran some tests, and found on power up and power down the output ripple can run as high as 1V. This was just a single part on a bench, so we can't guarantee that this would be typical behavior, but it seems it could certainly be problematic for your customer's design.

    Also, if the customer is locked into SOIC packaging, INA20X is the only series we offer with comparators in that package, so we cannot recommend an alternative.

  • hi Carolus,

    thank you for the answer!

    one more question, is the Vcm1-4 below change from low to high?  or it is no rule for the detail Vcm value? 

    in customer's real test, as you can see, when Vcm is 0.5V, the error voltage is biggest, when Vcm goes up or lower, error will decrease.  tks!


  • Dear Vera,

    the common mode voltages do not move from low to high here. These are the curves from different INA202 parts to demonstrate the potential variance in the output curve at low Vsense.

    As for the error reduction at higher Vcm, this makes sense for your customer's issue, as they move the common voltage above Vs (5.6V > 4.5V), which effectively moves them from operating case 2 to case 3.

    Hope this helps,