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INA186: Sections in datasheet

Part Number: INA186

Hi Sir,

I have a query about INA186.
There is "the maximum differential input signal times the gain plus VREF is less than the positive swing voltage VSP." in the datasheet.
For example, if gain is 50 V / V, and Vsp is 5V,
can the voltage between V+ ~ V- be normally measured to the current of about 0.1V?
is my thought correct?

In addition, as input differential overload in section 7.4.4.
If the voltage between V+ ~ V- exceeds the range that can be measured normally,
after returning to the normal value, it will output the correct value after 80 us.
This does not fail if the voltage of V+/ V- is less than Absolute maximum rated 42V.
Can I get the correct value in the measurement after 80us?

Thanks.
Regards,

  • Hey Frank1,

    You cannot expect the output voltage (Vout) to ever exceed VSP (swing to positive rail). For the INA186A2 (gain = 50V/V), the worst-case VSP = Vs-40mV. So with a supply voltage of Vs = 5V, you cannot expect the Vout to exceed 5V-40mV = 4.96V. If you refer this to the input, then this means you cannot accurately measure shunt voltages (Vshunt) greater 4.96V/50 = 99.2mV.

    Once Vshunt exceeds the full-scale range (99.6mV), the output will slam into the rail and saturate. Thus, once Vshunt goes back to a valid value (<99.6mV), there will be an overload recovery delay time of a 80µs typically. This will be true if the common-mode voltage at the input pins is < 42V, which is the Absolute Maximum Rating.

    However, the 80 µs time is only typical. This value could vary significantly depending upon several variables: the gain variant, the level of overdrive (1V versus 100mV), the fall time of the Vshunt from high to low, the output load, and temperature.

    The best course of action is to test the device in your end system and test it over the entire temperature range. If the overload recovery is well within the desired delay time, then the device should work for application.

    Sincerely,

    Peter