Maxim Integrated Products introduceb the DS4426, a low-cost, quad sink/source current DAC with tracking control. This device is an I²C-controlled, 7-bit current DAC with four output channels explicitly designed for power-supply margining and adjustment functions. Three of the DAC channels have additional circuitry to provide power-supply sequencing or tracking. Each output channel provides control of a dc-dc power supply by sinking or sourcing current directly into the power supply’s feedback node.
This technique allows existing power-supply designs to be margined and adjusted with minimal redesign, thus making the DS4426 well suited for any dc-dc power-supply application requiring low-cost, system-level voltage control, calibration, or margin testing. Typical end products include servers, routers, switches, and video processing cards.
The DS4426 powers up with all DAC outputs in a neutral (or zero current) output condition to minimize system-startup overhead requirements and allow the power-supply feedback resistors to perform in a standard manner. Secondary circuitry on three of the outputs allows the user to program supply tracking or sequencing for added control during power-up/down conditions. Each output is capable of sinking or sourcing currents from ±50µA to ±200microamps with ±10% accuracy. The DS4426 uses an external resistor to program this full-scale value for each channel to maximize versatility. The I²C bus is then used to set the current to any of the 127 sink or 127 source steps linearly up to the maximum full-scale value. Two address inputs allow up to four devices or sixteen separate supplies to be controlled on a single I²C bus.
The DS4426 is fully specified over the -40 to +85°C extended industrial temperature range, and is available in a 4mm x 4mm, 28-pin TQFN package. Pricing starts at $1.18 (10,000-up, FOB USA).