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INA190-Q1: IB with higher differential input voltage?

Kotaro Yamashita
Intellectual 2320 points
Part Number: INA190-Q1
Other Parts Discussed in Thread: INA190, INA190EVM

Hi team,

Is there any graph for input bias current with following conditions?

 - Differential Input Voltage ~3V

 - Vs = 5V, Vref = 0V

D/S only mentioned IB with <60mV differential input voltage but I would like to know this.

Regards,

Kotaro Yamashita

  • 0
    TI__Mastermind 32205 points

    Hello Kotaro,

    Inside the INA190 there is a bidirectional diode in between IN+ and IN- with a ~3.3 kOhm of current-limiting resistance. So for V_differential of 3V there could be 909uA of differential current into IN+ and then out of IN-. I just measured 580uA using the INA190EVM, but this could be ammeter error. At 25V V_diff, I measured 7.3mA, which is closer to the 3.3Kohm of resistance once the differential input diode has turned on.

    Hope this helps.

    Best, 

    Peter

  • 0 in reply to Peter Iliya
    TI__Intellectual 2320 points

    Hello Peter,

    Thanks. I have questions as below.

    - ~3.3kOhm resistor is actual resistance? Is that same at Vref = 0V condition?

    - Does the parameter have temp drift?

    Regards,

    Kotaro Yamashita

  • 0 in reply to Kotaro Yamashita
    TI__Mastermind 32205 points

    Hey Kotaro,

    Yes the 3.3kOhm is made up of actual resistors and are always there regardless of the Vref or Vs conditions. This resistance should not vary much over temperature. The resistance probably varies more over process variation than with temperature. A conservative variance is +/-15% over process and temperature.

    Best,

    Peter

  • 0 in reply to Peter Iliya
    TI__Intellectual 2320 points

    I have 2 questions below.

    - Does INA190 with RSW package have same internal 3.3kOhm resistors?

    - My customer have tested with following condition. However they measured 4-5pin resistance = 13.5kOhm or so.  What is the cause of this?

    1pin：GND

    2pin：GND

    3pin：5V

    4pin：OPEN

    5pin：OPEN

    6pin：510ohm

    Regards,

    Kotaro Yamashita

  • 0 in reply to Kotaro Yamashita
    TI__Mastermind 32205 points

    Hey Kotaro,

    Why is customer measuring resistance between pins 4 and 5? Pin 5 is a NC ("no connect"). Also what does the 510-Ohm for pin 6 represent?

    Please detail how the measurement was performed and under what testing conditions and device configuration. A schematic and data table would be useful.

    It's possible that ammeter error can skew the resistance calculation during testing with low input differential voltages. Additionally, any R =V/I calculation will include errors from the forward-biased resistance of the diode and Vf (diode voltage drop).

    Sincerely,

    Peter

  • 0 in reply to Peter Iliya
    TI__Intellectual 2320 points

    Hi Peter,

    I got detail information from the customer. Let's discuss at offline.

    Regards,

    Kotaro Yamashita