Maxim Integrated Products has introduced a low-cost, quad sink/source current DAC with tracking control.
The DS4426 is an I2C-controlled, 7-bit current DAC with four output channels 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. The technique allows existing power-supply designs to be margined and adjusted with minimal redesign, thus making the DS4426 ideal 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 ±50 microamps to ±200 microamps with ±10 percent 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 degrees Celsius extended industrial temperature range, and is available in a 4 mm x 4 mm, 28-pin TQFN package. Pricing starts at $1.18 (10,000-up, FOB USA).