This open loop example circuit offers a way to use a DAC to precisely control a load current. The load current flows through the FET and into the 1 Ohm, 10W resistor shown in the bottom right corner of the figure. In this example, the LTC2641 is supplied with 5V at VDD and the LT1019 external reference provides a low-noise 2.5V source at the REF pin. The LTC2641’s output can range from 0V to 2.5V, providing the ability to fine-tune the current source between 0A and 2.5A with 65,536 unique steps.

