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INA225: Saturating Output Amplifier to Vin Bias Level

Adam Mc Gaffin
Mastermind 30000 points
Part Number: INA225

Hello Team,

Customer reached out to us with a question regarding the output amplifier saturation. They would like to know if it is okay to regularly saturate the output amplifier to Vin bias level? For example if Vs is connected to 3.3V, and the signal between IN+, IN- regularly exceeds level clamps to 3.3V on output, will this cause any issues?

  • 0
    TI__Mastermind 27715 points
    Hello Adam,

    Thank you for your question. Our engineers will analyze and respond when we return to the office on Monday.

    Best regards,

    Ian Williams
    Applications Manager
    Current & Magnetic Sensing
  • 0 in reply to Ian Williams
    TI__Mastermind 32395 points
    Hey Adam,

    It is a little difficult to understand the operation here, but there should be no issue with regularly saturating (or railing) the output of the INA225. The INA225's VOUT will saturate when the input differential voltage (VIN) exceeds the full-scale input range which is ~125mV for gain 25V/V and VS=3.3V. We specify that Absolute Maximum VIN can actually be -40V to +40V, which far exceeds the full-scale input. Overall, the output saturates because the output transistors are hitting saturation and there really is no detriment to the device operation if this saturation is regularly occurring.

    Input current on any pin should be limited to 5mA as a general caution and of course the absolute maximum rating cannot be violated.

    Hope this helps.

    Sincerely,
    Peter Iliya
    Current Sensing Applications
  • 0 in reply to Peter Iliya
    TI__Mastermind 27715 points

    Hi Adam,

    I'd just like to add that Peter's guidance applies to basically any amplifier-based device.

    Best regards,

    Ian Williams

  • 0 in reply to Ian Williams
    TI__Mastermind 30000 points
    Hi Peter, Ian,

    Thank you both for the help. Believe this answers customers questions, but will let you know if anything else comes up.