MAX1677

19-1403; Rev 0; 11/98 NUAL KIT MA ATION U EET L H A S V E S DATA W O L L FO Compact, High-Efficiency, Dual-Output Step-Up and LCD Bias DC-DC Converter General Description Features o No External FETs Required o Main Output Up to 350mA for Logic Supply Fixed 3.3V or Adjustable (2.5V to 5.5V) Synchronous Rectification for High Efficiency (up to 95%) 300kHz (200kHz to 400kHz Synchronizable) Fixed-Frequency PWM Operation o Secondary Output Up to +28V or -28V for LCD Bias Programmable Current Limit o 0.7V to 5.5V Input Voltage Range o 20µA Quiescent Current o 1µA Shutdown Current o Low-Battery Comparator o Small 16-Pin QSOP Package MAX1677 The MAX1677 is a compact, high-efficiency, dual-output boost converter for portable devices needing two regulated supplies, typically for logic and liquid crystal displays (LCDs). Operation with inputs as low as 0.7V allows the MAX1677 to accept 1, 2, or 3-cell alkaline, NiCd, or NiMH batteries as well as 1-cell lithium-ion batteries. The device requires no external FETs and can maintain regulation while consuming only 20µA, making it ideal for hand-held pen-input and PDA devices operating with low-current “sleep” states. The MAX1677’s primary regulator supplies up to 350mA at either a factory-preset 3.3V or an adjustable 2.5V to 5.5V output. On-chip synchronous rectification provides efficiencies up to 95%. 300kHz (or externally clocked) pulse-width-modulation (PWM) operation is particularly suitable for applications needing low noise, such ...