DESCRIPTION
The SP6644/6645 devices are high-efficiency, low-power step-up DC-DC converters ideal for single or dual alkaline cell applications such as pagers, remote controls, pointing devices, medical monitors, and other low-power portable end products. Designers can control the SP6644 device with an active LOW shutdown input. The SP6644 device features an active low output for batteries below +1.0V. The SP6645 device features an active low output for batteries below +2.0V. Both devices contain a 0.8Ω synchronous rectifier, a 0.5Ω N-channel MOSFET power switch, an internal voltage reference, circuitry for pulse-frequency-modulation, and an under voltage comparator. The output voltage for the SP6644/6645 devices is preset to +3.3V + 4% or can be adjusted from +2V to +5.5V by manipulating two external resistors

■ 90mA Output Current at 1.3V Input
■ 190mA Output Current at 2.6V Input
■ +2V to +5.5V Output Range
■ 0.88V Guaranteed Start-Up
■ 92% High Efficiency
■ 1.6µA Quiescent Supply Current at VBATT
■ Reverse Battery Protection
■ Internal Synchronous Rectifier
■ 5nA Logic Controlled Shutdown Current From VBATT
■ Low-Battery Detection Active LOW Output
■ Small 8 Pin MSOP Package
■ No External FETs
■ Flexibility to Optimize Inductor Type with Programmable Peak Current Control