MAX1761

19-1835; Rev 0; 10/00 KIT ATION EVALU LE B A IL A AV Small, Dual, High-Efficiency Buck Controller for Notebooks General Description Features o Free-Running On-Demand PWM o Selectable Light-Load Pulse-Skipping Operation o ±1% Total DC Error in Forced-PWM Mode o 5V to 20V Input Range o Flexible Output Voltages OUT1: Dual Mode™ Fixed 2.5V or 1V to 5.5V Adjustable OUT2: Dual Mode Fixed 1.8V or 1V to 5.5V Adjustable o Output Undervoltage Protection o Complementary Synchronous Buck o No Current-Sense Resistor o 4.65V at 25mA Linear Regulator Output o 4µA V+ Shutdown Supply Current o 5µA VL Shutdown Supply Current o 950µA Quiescent Supply Current o Tiny 16-Pin QSOP Package MAX1761 The MAX1761 dual pulse-width-modulation (PWM), step-down controller provides high efficiency, excellent transient response, and high DC output accuracy in an extremely compact circuit topology. These features are essential for stepping down high-voltage batteries to generate low-voltage CPU core, I/O, and chipset RAM supplies in PC board area critical applications, such as notebook computers and smart phones. Maxim’s proprietary Quick-PWM™ quick-response, constant-on-time PWM control scheme handles wide input/output voltage ratios with ease and provides “instant-on” response to load transients while maintaining a relatively constant switching frequency. The MAX1761 achieves high efficiency at reduced cost by eliminating the current-sense resistor found in traditional current-mode PWMs. Efficiency is fu...