High-Side Current Sensing: Difference Amplifier vs. Current-Sense Amplifier

Accurate high-side current sensing is necessary in applications such as motor control, solenoid control, and power management. In these applications, monitoring the current on the high side permits improved diagnostic capabilities and maintains the integrity of the ground path by avoiding the introduction of shunt resistance.

There are a number of semiconductor options for the high-side current sensing function. The choices among integrated circuit (IC) devices can be classified into two, quite different categories of high-voltage architecture: current-sense amplifiers and difference amplifiers. This paper identifies and explains some of the key differences between these architectures in order to help designers choose the devices best-suited to their applications. Two high-voltage parts are compared: the AD82062 bidirectional difference amplifier and the AD82103 bidirectional current-sense amplifier.