MAX1637

19-1321; Rev 1; 2/98 KIT ATION EVALU LE B A IL A AV Miniature, Low-Voltage, Precision Step-Down Controller General Description ____________________________Features o ±2% DC Accuracy o 0.1% (typ) DC Load Regulation o Adjustable Switching Frequency to 350kHz o Idle Mode™ Pulse-Skipping Operation o 1.10V to 5.5V Adjustable Output Voltage o 3.15V Minimum IC Supply Voltage (at VCC pin) o Internal Digital Soft-Start o 1.1V ±2% Reference Output o 1µA Total Shutdown Current o Output Overvoltage Crowbar Protection o Output Undervoltage Shutdown (foldback) o Tiny 16-Pin QSOP Package MAX1637 The MAX1637 synchronous, buck, switch-mode powersupply controller generates the CPU supply voltage in battery-powered systems. The MAX1637 is a strippeddown version of the MAX1636 in a smaller 16-pin QSOP package. The MAX1637 is intended to be powered separately from the battery by an external bias supply (typically the +5V system supply) in applications where the battery exceeds 5.5V. The MAX1637 achieves excellent DC and AC output voltage accuracy. This device can operate from a low input voltage (3.15V) and delivers the excellent load-transient response needed by upcoming generations of dynamic-clock CPUs. Using synchronous rectification, the MAX1637 achieves up to 95% efficiency. Efficiency is greater than 80% over a 1000:1 load-current range, which extends battery life in system-suspend or standby mode. Excellent dynamic response corrects output load transients caused by the latest dynamic-...