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INA236: Least Significant Bit and Full-Scale Value Does Not Correspond to 16-Bit Resolution

Part Number: INA236


I have a basic question about the INA236 least significant bit (LSB) size versus the full-scale (FS) value.

Why does it appear that the full 16-bit resolution is not being used?  It appears that the device is actually a 15-bit device.  I must be missing something.

The device is a 16-bit device according to the datasheet's electrical specifications so, the LSB value (theoretical) should be the full-scale value divided by 2^16.

Using the default values for the ADC range from the datasheet the LSB value is 2.5uV and the full-scale value is 81.92mV.

0.08192/2^16 is not equal to 2.5uV, but 0.08192/2^15 is equal to 2.5uV.

In addition, on Page 25 of the datasheet the current LDB value is calculated by dividing the maximum current to be measured by 2^15 and not 2^16.




  • Hi Edward, 

    The internal ADC is signed, so it would have 1 sign bit and the remaining 15 bits would be dedicated to the value. This is why there are only 15 useable bits for value but it is still a 16-bit part. Please let me know if you have any questions.