Programmable-Gain Sense Amplifier Handles Bidirectional Current Sensing

As a high-side current-sense amplifier composed of two complete amplifiers with a combined single bipolar output, the LTC6104 from Linear Technology Corp. is well-suited for bidirectional operation. The dual-amplifier topology offers exceptional flexibility by allowing gain programmability for each current-sense direction. The use of separate amplifiers also allows monitoring of a single current-sense resistor or separate sense resistors. Typical applications include battery-charging circuitry, H-bridge driver circuits, and servo controls.

The LTC6104’s input bias current is 170 nA max, and its input offset voltage is ±450 µV max. This precision performance allows the device to resolve tiny current and operate over a wide dynamic range. The amplifier withstands voltages up to 70 V, which is important when power-supply failures or catastrophic load changes can lead to voltage flyback conditions. With a response time under 1 µs, the LTC6104 is well-suited for an automatic power shutdown function under fault conditions. Users set the gain with three external resistors, and thus the use of precision resistors permits accuracy better than 1%.