INA199: max offset voltage vs supply voltage

Hello,

Thank you for using the TI forums. The data you can use to determine how the offset voltage varies with the supply voltage change is called Power Supply Rejection (PSR). For the INA199, this information is found in table 7.5 of the datasheet titled “Electrical Characteristics” shown below.

Since the INA199 allows up to 26V supply, you can use 19V safely, and the PSR is calculated as an offset from a 5V supply. Since the PSR for the INA199 is +/-0.1µV/V, operating at 19V could have an offset around 1.4µV from the equation (19-5)*.1µ = 1.4µV. Note that the datasheet only specifies this PSR for up to 18V, so with a 19V supply it may be a little different. Also note that this offset would be added to the offset already associated with the device (Vos) which is typically around -/+5µV but could up to +/-150µV.

If you would like more information on PSR, you could watch our “Understanding power supply rejection error” video from our “Getting Started with Current Sense Amplifiers” video training series, which can be found at this link:

https://training.ti.com/getting-started-current-sense-amplifiers-session-11-understanding-power-supply-rejection-error?cu=456802

user2012342 said:

{...} I need to properly detect 12.5mV (max. error shouldn't exceed 20%) on the 0R18 current sense resistor (there's a comparator connected to the output).

Given the requirement, I think it is also worth to mention the INA301, which has an built in comparator, as a possible solution for your evaluation