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, Ste...
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...