Sink/source current DACs simplify power-supply adjustments

A control technique that allows existing power-supply designs to be margined and adjusted with minimal redesign is what stands-out about Maxim Integrated Products' latest 7-bit current DACs. The dual channel DS4422 and quad channel DS4424 sink/source current DACs are I2C-controlled, and provides control of a DC-DC power on each output channel by sinking or sourcing current directly into the power supply's feedback node. Target applications include servers and video processing cards.

The chips boast a zero-current output condition, minimising system-startup overheads. To maximise versatility, the DACs use an external resistor to program the full-scale current for each output from 50microamps to 200microamps with 6% accuracy. The I2C bus can then be used to linearly set the output currents to any of the 127 sink or 127 source steps up to the maximum value. Two address inputs allow up to four devices or sixteen separate supplies to be controlled on a single I2C bus.

Specified over the -40 degrees Celsius to +85 degrees Celsius extended temperature range, the DS4422/DS4424 are available in a 3mm x 3mm, 14-pin TDFN package.

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