Power Supply 28-Pin QSOP

The MAX769 is a complete buck/boost power supply and monitoring system for two-way pagers or other low-power digital communications devices. Few external components are required. Included on-chip are: An 80mA output, synchronous-rectified, buck/boost DC-DC converter with a digitally controlled +1.8V to +4.9V output. The DC-DC converter is unique, since it provides a regulated output for battery inputs that are both less than and greater than the output voltage, without using transformers. Three low-noise linear-regulator outputs Three DAC-controlled comparators for software-driven, 3-channel A/D conversion SPI-compatible serial interface Reset and low-battery (LBO) warning outputs Charger for NiCd/NiMH, lithium battery, or storage capacitor for RF PA power or system backup Two 1.8O (typical), serial-controlled, open-drain MOSFET switches for beeper or vibrator drive An evaluation kit for the MAX769 (MAX769EVKIT) is available to aid in design and prototyping.

• Regulated Step-Up/Step-Down Operation
• 80mA Output from 3 Cells
• 85% Efficiency
• 13µA Idle Mode (coast) Current
• Selectable Low-Noise PWM or Low-Current PFM Operation
• PWM Operating Frequency Synchronized to Seven Times an External Clock Source
• Operates at 270kHz with No External Clock
• Automatic Backup-Battery Switchover