LM2640 Datasheet | National Semiconductor

Description The LM2640 is a dual step-down power supply controller intended for application in notebook personal puters and other battery-powered equipment. Fixed-frequency synchronous drive of logic-level N-channel power MOSFETs is bined with an optional pulse-skipping mode to achieve ultra efficient power conversion over a 1000:1 load current range. The pulse-skipping mode can be disabled in favor of fixed-frequency operation regardless of the load current level. High DC gain and current-mode feedback control assure excellent line and load regulation and a wide loop bandwidth for fast response to dynamic loads. An internal oscillator fixes the switching frequency at 200 k Hz. Optionally, switching can be synchronized to an external clock running as fast as 400 k Hz. An optional soft-start feature limits current surges from the input power supply at start up and provides a simple means of start-up sequencing. Logic-level inputs allow the controllers to be turned ON and OFF separately. Key Specifications n n n n n 96% efficient 5.5 to 30V input range Dual outputs adjustable from 2.2 to 6V 0.5% typical load regulation error 0.002%/V typical line regulation error Features n 200 k Hz fixed-frequency switching n Switching synchronization with an external signal up to 400 k Hz n Optional pulse-skipping mode n Adjustable secondary feedback n Input undervoltage lockout n Output undervoltage shutdown protection n Output overvoltage shutdown protection n Programmable soft-start (each controller) n 5V, 50 m A linear regulator output n Precision 2.5V reference output n 28-pin TSSOP Applications n Notebook and subnotebook puters n Wireless data terminals n Battery-powered instruments Connection Diagram and Ordering Information 28-Lead TSSOP (MTC) DS100148-1 Top View Order Number LM2640MTC-ADJ See NS Package Number MTC28 © 1999 National Semiconductor Corporation DS100148 .national. Pin Description Pin # 1 2 3 4 5 6 7 8 9 10 CSH2 FB2 P2 SS2 ON/OFF2 SD SYNC GND REF...