MAX653

19-4505; Rev 3; 8/97 KIT ATION D EVALU CLUDE IN N IO T A M R O INF 5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Converters ____________________________Features o High Efficiency for a Wide Range of Load Currents o 10µA Quiescent Current o Output Currents Up to 225mA o Preset or Adjustable Output Voltage: 5.0V (MAX639) 3.3V (MAX640) 3.0V (MAX653) o Low-Battery Detection Comparator o Current-Limiting PFM Control Scheme _______________General Description The MAX639/MAX640/MAX653 step-down switching regulators provide high efficiency over a wide range of load currents, delivering up to 225mA. A current-limiting pulse-frequency-modulated (PFM) control scheme gives the devices the benefits of pulse-width-modulated (PWM) converters (high efficiency at heavy loads), while using only 10µA of supply current (vs. 2mA to 10mA for PWM converters). The result is high efficiency over a wide range of loads. The MAX639/MAX640/MAX653 input range is 4V to 11.5V, and the devices provide lower preset output voltages of 5V, 3.3V, and 3V, respectively. Or, the output can be user-adjusted to any voltage from 1.3V to the input voltage. The MAX639/MAX640/MAX653 have an internal 1A power MOSFET switch, making them ideal for minimum-component, low- and medium-power applications. For increased output drive capability, use the MAX649/MAX651/MAX652 step-down controllers, which drive an external P-channel FET to deliver up to 5W. MAX639/MAX640/MAX653 ______________Ordering Informatio...