Friday, July 11, 2008

Maxim quad and dual sink-source current DACs for power-supply adjustment

Maxim has introduced quad and dual sink-source current DACs specifically designed for power-supply adjustment, the DS4422 and DS4424.

Both are I2C-controlled with 7bit current DACs designed to control a DC-DC converter by sinking or sourcing current directly into the power supply's feedback node. "This control technique allows existing power-supply designs to be margined and adjusted with minimal redesign, making the devices ideal for servers and video processing cards," claimed the firm.

The chips power-up with their outputs open circuit to allow the power-supply feedback resistors to perform naturally. This removes the need to address the chip immediately at start-up.

DAC full scale output current is programmed between 50 and 200µA with an external resistor with ±six per cent 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.

The DS4422 (two DAC) and DS4424 (four DAC) are specified over -40 to +85°C and come in a 3x3mm 14pin TDFN package.


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