RT8203

RT8203 High-Efficiency, Quad Output, M ain Power- Supply Controllers for Notebook Computers General D escription The RT8203 dual step-down, switch-mode power-supply (SMPS) controllers generate logic-supply voltages in battery-powered systems. The RT8203 include two pulsewidth modulation (PWM) controllers, adjustable from 2V to 5.5V or fixed at 5Vand 3.3V . These devices feature two linear regulators providing 5V and 3.3V always-on outputs. Each linear regulator provides up to 100mA output current with automatic linear regulator bootstra pping to the main SMPS outputs. The RT8203 include on-board power-up sequencing, a power-good (PGOOD) output, internal softstart, and soft-shutdown output discharge that prevents negative voltage s on shutdown. RichTek's proprietary Mach-PWMTM “ instant-on” response, con stant on-time PWM control scheme operates without sense resistors and provides 100n s respon se to loa d transients while maintaining a relatively con stant switching frequency . The unique ultra sonic mode maintain s the switching frequency above 25kHz, which eli minates noise in audio pplications. a Other features include diode-emulation, which maximizes efficiency in light-load applications, and fixed-frequency PWM mode, which reduces RF interference in sensitive application s. The R T8203 provides a pin-sele ctable switching frequency, allowing either 200kHz/300kHz or 400kHz/500kHz operation of the 5V/3.3V SMPSs, respectively . The R T8203 is availa ble in SSOP-28 pa ckage...