Simplified Block Diagram
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- Built-In Synchronous Rectifier
- 0.88V Guaranteed Start-Up
- Ultra-Small µMAX Package: 1.1mm High
- 83% Efficiency
- 4µA Quiescent Supply Current into BATT Pin
- 2µA Logic-Controlled Shutdown (MAX1642)
- Two Undervoltage Detectors (MAX1643)
- 2V to 5.2V Output Range
- 20mA Output Current at 1.2V Input
- Reverse Battery Protection
- Personal Medical Monitors
- Pointing Devices
- Remote Controls
- Single-Cell Battery-Powered Devices
Each device consists of an internal 1Ω, N-channel MOSFET power switch; a built-in synchronous rectifier that acts as the catch diode; an oscillator; a reference; and pulse-frequency-modulation (PFM) control circuitry. Both devices feature an independent undervoltage comparator (PFI/PFO). The MAX1642 also includes a 2µA logic-controlled shutdown mode. The MAX1643 offers a dedicated low-battery detector (BATTLO) in lieu of shutdown.
The output voltage for each device is preset to 3.3V ±4%, or can be adjusted from +2V to +5.2V using only two resistors.