Digital Resistors Simplify Automated Power Trimming

Designed for use in automated power supply calibration circuits, the DS3904 nonvolatile, digital resistor contains three low-temperature-coefficient digital resistors with 128 user-selectable positions per resistor. Each resistor has a typical resistance range from 425? to 20 k? with a high-impedance option that allows the resistor to function as a digital switch. The device operates from a 2.7V to 5.5V supply and communication is via a two-wire serial interface. It also includes an address pin that allows two DS3904s to operate on the same bus. Available in an eight-lead microSOP, prices start at $0.70 each/1,000. DALLAS SEMICONDUCTOR, Dallas, TX. (800) 998-8800.