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INA198A-Q1

hideyuki sakai
Mastermind 6250 points
Other Parts Discussed in Thread: INA198A-Q1

Dear, Sir.

My customer is considering to apply INA198A-Q1 replaced from LT's.

V+=5V, VIN+=20V, Rshunt=0.25mOHM

They want to monitor 0 to 200A loading current using it.

We would like to make sure these 2 points previous his evaluation.

1) How much is the TOTAL ERROR %(output) of INA198A-Q1?

2) The Data sheet page 10, figure2 is described on a "larger-than-normal" offset(approx.300mV)

    under Low Vsense CASE3/ Vsense<20mV, Vs<Vcm<80V. Repeat Vin=on=>off=>on.

    How much is the tolerance of such abnormal output offset voltage(300mV+- ?%)?

Best Regards,

 

 

  • 0
    TI__Genius 14070 points

    Hello Sakai-san,

    Please see the comments below:

    1) How much is the TOTAL ERROR %(output) of INA198A-Q1?

    •  The total output error is 3% (max under full temperature range), and this error includes the effects of gain error and Vos. The information can also be found on Pg. 3 of the datasheet.

    2) The Data sheet page 10, figure2 is described on a "larger-than-normal" offset(approx.300mV)

        under Low Vsense CASE3/ Vsense<20mV, Vs<Vcm<80V. Repeat Vin=on=>off=>on.

        How much is the tolerance of such abnormal output offset voltage(300mV+- ?%)?

    • The 300mV offset (the Actual Line in Figure 2) represents the worst case offset response under these conditions. Please note though that as the current shunt is operating outside its optimal region, that all other parameters (such as gain error) will degrade in accuracy as well. As these Low Sense Cases are outside of the intended operating range, there is no other information on how the device operates during these cases.

    Also, to clarify, the device is to monitor 0 up to 200mA correct?

    Thank you and Best Regards,

    Wen-Shin Wang

  • 0 in reply to Wen-Shin Wang
    Mastermind 6250 points

    Dear, Wang-san. 

    I appreciate your reply. 

    V+=5V, VIN+=20V, External Rshunt=0.25mOHM

    They want to monitor 0A ~ 200A loading current using it.

    0.25mOHM*200A=50mV

    50mV*100(Fixed Gain)=5V

    Total output error is 3%. I wonder the offset will be larger-than-normal  offset & 

    the tolerance will be come worse than normal?

    Best Regards, 

  • 0 in reply to hideyuki sakai
    TI__Genius 14070 points

    Hello Sakai-san,

    Thank you for the clarification regarding the current.

    For the question regarding the offset: do you mean for Low Sense Case 3 specifically? When the device is used as intended, then offset and tolerance are 3mV (max) and 3% (max) respectively.

    For Low Sense Case 3, yes, as the offset will be larger than normal, the tolerance will also be worse than normal. The datasheet mentions that as the device was not designed for precise operation in this region, then the output accuracy will degrade as well. As mentioned previously, there is very little data regarding how the device will specifically act within this region besides what is stated in the datasheet.

    Best Regards,

    Wen-Shin Wang