LinFinity Intros LX1681/82 Family of Controller ICsMay 31, 1999 by Jeff Shepard
LinFinity Microelectronics Inc. (Garden Grove, CA) introduced the LX1681/82 family of monolithic pulse-width modulator controller-integrated circuits for implementing flexible, low-cost buck (step down) regulator supplies with a minimum of external components for 5V to 3.3V or lower power supplies. Typical conversions are from 5V to 3.3V, 5V to 2.5V or 5V to 1.8V for applications on computer motherboards, hard disk drives, graphic cards and general purpose dc/dc converters. The LX1681 is designed for standard buck configurations, implemented with a standard n-channel FET and Schottky diode. The LX1682 offers greater efficiency in synchronous rectifier configurations driving a pair of FETs. Both devices are supplied in small 8-pin surface mount packages and feature soft-start hiccup-mode current limiting and chip-enable functions previously found only in devices having much larger pin counts. A constant frequency of 200kHz simplifies design-in, as no external compensation is required. Output voltage can be set to any voltage between the 1.25V reference voltage and the input voltage, by means of a resistor divider. Samples and production quantities are available immediately. OEM quantities of 1,000 are priced at $1.14 for the LX1681/82 graded for commercial applications (0 to +70 degrees C) and at $1.66 for industrial applications (-40 to +85 degrees C).