TI’s smart high side switches implement a current mirror circuit that mimics the current going through the output and reflects it by an internal ratio and outputs a current on the CS pin.

Due to the internal current mirror, current sense can vary as a result of the current load. The current sense ratio K_SNS is directly affected by the sense current and becomes more accurate with increasing load current which is reflected in the Current-Sense accuracy value, dK/K, As a result, the output current measured from the SNS pin is affected at different load currents and operates optimally at currents closer to the maximum current the device is rated to operate at. For the TPS1H100-Q1, for example, the optimal current sense accuracy occurs when the operating load current I_OUT is 1A or greather. Within that range, the TPS1H100-Q1 is able to measure the load current with an accuracy of up to 3% depending on the load current.