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INA105: Output Clipping

John Yu32
Prodigy 30 points

Part Number: INA105
Other Parts Discussed in Thread: INA133, INA132

I am using the INA105 in a difference amp configuration to receive a signal output which can go up to +10.5V. When the input signal rises above +9V the output of the INA105 will follow the input signal to almost 10V and then clips to around 8V. I am using  +/- 12V supplies for the INA105. I increased the +12V supply to +13.1V and it appears to work better. I have another device on the board that prevents me to go beyond 13.2V on the positive power supply rail.

On the s cope capture, Trace 1 is the input signal and Trace 2 is the output signal form the INA105.

  • 0
    TI__Guru 74311 points

    John,

    There is a difference between the input common-mode and input differential voltage but it is difficult to follow what input voltage you refer to in your write up.  The input common-mode voltage is specified as +/-20V and input differential voltage as +/-10V for +/-15V supplies (5V away from rails-see below), which translates into +/-14V input common-mode voltage and +/-7V input differential voltage for +/-12V supplies,  and I suspect you are violating one of these input voltage ranges. 

    If you need further assistance, please show your circuit schematic showing actual input voltage applied to each input as well as Ref voltage used.

  • 0 in reply to Marek Lis
    Prodigy 30 points

    Hi Marek,

    Thanks for the feedback on the differential voltage range limitation on the INA105. I wasn't expecting the input voltage range has to be 5V below the power supply rail for this device. Do you have a recommendation for a newer device with similar performance as the INA105 but allows input range of 10V with 12V power rails.

    Thanks.

  • 0 in reply to John Yu32
    TI__Guru 74311 points
    Please consider using INA132 or INA133 with wider input voltage range than INA105.