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LMP8601: Max. differential input voltage

Marks Greulich
Intellectual 540 points
Part Number: LMP8601

Hi guys,

I`m not sure if I understand it correctly. Max. Voltage on V+, V- is -22V...60V (to GND). 

But what is the max. differential voltage between the pins V+ and V-??? I guess I cant supply -22V on one pin and +60V on the other pin what is a voltage of 82V...

Thanks,

Markus

  • 0
    Intellectual 540 points

    Here some simulation data. Realized that the gain is pretty much changing when I have a diff-Voltage (10...50mV). The gain is there around 11 instead of 10?

    Could that be?

  • 0 in reply to Marks Greulich
    TI__Mastermind 18790 points

    Markus,

    Oddly enough, that seems to be the case. Check out this older forum post where this question was answered.

  • 0 in reply to Carolus Andrews
    TI__Mastermind 18790 points

    Markus,

    Sorry, didn't see your follow-up. The reason you're seeing the "gain" change here is most likely explained by the offset voltage and the bias currents flowing through the 10 ohm resistor.

    The worst case offset voltage for this device is 1mV, and the typical offset is 150uV. This is an older device, so I'm not quite sure where the spice model is set to in terms of this, but as the current in the shunt drops, these errors will tend to start to dominate the measurement. I ran a quick RSS analysis for your current use case, and here's what the error looks like in comparison to current:

    This does not take into account the bias currents that potentially will add additional substantial error since the shunt resistor is so large.