INA194: INA194

Hey Ian,

Well for the INA194 when the Vsense < 20mV, then most of the performance and accuracy will be degraded and non-specified. In the Electrical Characteristics table, the output voltage (Vout) is specified for Vsense < 20mV. For the INA194 with Vs > VCM and Vsense < 20mV, the VOUT could be anything < 1V. In other words you cannot trust the Vout to be tracking Vsense when Vsense is less than 20mV. Vout could be anything between 0V and 1V when Vsense < 20mV.

To determine accuracy when the device is acting linearly you need to calculate the new input offset based upon VCM and Vs. 

Vosi = initial specified offset = ± 2 mV

Vos_CMRR = offset due to CMRR = |12-3.3|*10^(-80dB/20) = ± 870 uV.

Vos_PSRR = offset due to PSRR = |12-0|*100uV/V = ± 1.2 mV.

Vos_total = 2 mV + 1.2 mV + 0.87mV = ± 4.07 mV

You can learn about calculating error with our free training courses here:

https://training.ti.com/ti-precision-labs-current-sense-amplifiers

Sincerely,

Peter

Hey Ian,

The range of Vout for Vs>Vcm and Vsense <20mV is guaranteed because the 1V is a maximum specification. Maximum and minimum specifications are limit specs where the value is guaranteed over device population. Consider watching this video on reading CSA datasheets from TIs Precision Labs series:

https://training.ti.com/ti-precision-labs-current-sense-amplifiers-reading-current-sense-amplifier-datasheets?context=1139747-1139745-1138708-1139729-1140508

Best,

Peter