MAX1651
Description
The MAX1649/MAX1651 Bi CMOS, step-down, DC-DC switching controllers provide high efficiency over loads ranging from 1m A to more than 2.5A. A unique, currentlimited pulse-frequency-modulated (PFM) control scheme gives these devices the benefits of pulse-width-modulation (PWM) converters (high efficiency at heavy loads), while using only 100µA of supply current (vs. 2m A to 10m A for PWM converters). Dropout performance down to 300m V is provided by a high switch duty cycle (96.5%) and a low current-sense threshold (110m V). A high switching frequency (up to 300k Hz) allows these devices to use miniature external ponents. The MAX1649/MAX1651 have dropout voltages less than 0.3V at 500m A and accept input voltages up to 16V. Output voltages are preset at 5V (MAX1649), or 3.3V (MAX1651). They can also be adjusted to any voltage from 1.5V to the input voltage by using two resistors. These step-down controllers drive external P-channel MOSFETs at loads greater than 12.5W. If less power...
