I need a quick atta-boy and determine if my error analysis is correct for the INA219 which I am using in my circuit.
Application specs:
Vdd = 5V
Vcm = 15V
Vsense = 100mV, PGA = 4 to allow for 100mV Vsense
I am presuming Vos, Gain error, PSRR, and CMRR will be the dominant errors and I am ignoring drift and bias currents.
Error due to Vos: (Vos / Vsense) * 100% = (150uV / 100mV) * 100% = 0.15%
Error due to Gain: 0.04% (directly from datasheet)
Error due to CMRR: 100dB MIN = 10uV/V: = ((Vcm(datasheet) - Vcm(app) * CMRR(error)) / Vsense) * 100% = ((15V - 12V) * 10uV/V) / 100mV = 0.03%
Error due to PSRR: 100dB TYP = 10uV/V (from datasheet): [PSRR(datasheet) - PSRR(app) / Vsense] * 100% = (((3.3V - 5.0V * 10uV/V) / 100mV) *100%) = 0.017%
Worst case error: Vos(error) + Gain(error) + CMRR(error) + PSRR(error) = 0.15% + 0.04% + 0.03% + 0.017% = 0.237%
The only concerns I have there are no MAX specs for PSRR and current gain error, as well as current gain error is only speced for PGA gain of +1.
Am I off my horse?
-Ken
