MAX1641

19-1245; Rev 0; 7/97 KIT ATION EVALU LE B A IL A AV Adjustable-Output, Switch-Mode Current Sources with Synchronous Rectifier ____________________________Features o 95% Efficiency o +5.5V to +26V Input Supply Range o 2V to 24V Adjustable-Output Voltage Range o 100% Maximum Duty Cycle (Low Dropout) o Up to 500kHz PWM Operation o Optional Synchronous Rectifier o 16-Pin QSOP Package o Current-Sense Accuracy: 2% (MAX1641) 5.3% (MAX1640) _______________General Description The MAX1640/MAX1641 CMOS, adjustable-output, switch-mode current sources operate from a +5.5V to +26V input, and are ideal for microprocessor-controlled battery chargers. Charging current, maximum output voltage, and pulse-trickle charge are programmed with external resistors. Programming the off-time modifies the switching frequency, suppressing undesirable harmonics in noise-sensitive circuits. The MAX1640’s highside current sensing allows the load to connect directly to ground, eliminating ground-potential errors. The MAX1641 incorporates a low-side current sense. The MAX1640/MAX1641 step-down pulse-width-modulation (PWM) controllers use an external P-channel MOSFET switch and an optional, external N-channel MOSFET synchronous rectifier for increased efficiency. An internal low-dropout linear regulator provides power for the internal reference and circuitry as well as the gate drive for the N-channel synchronous rectifier. The MAX1640/MAX1641 are available in space-saving, 16-pin narrow QSOP packages. MAX1...