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MAX1570：White LED Current Regulator with 1x/1.5x High-Efficiency Charge Pump

The MAX1570 fractional charge pump drives up to five white LEDs with regulated constant current for uniform intensity. The MAX1570 maintains the highest possible efficiency over the full 1-cell lithium-ion (Li+) battery input voltage range by utilizing a 1x/1.5x fractional charge pump and very-low-dropout current regulators. The MAX1570 operates with 1MHz fixed-frequency switching, allowing for tiny external components. The regulation scheme is optimized to ensure low EMI and low input ripple. An external resistor sets the full-scale LED current, while two digital inputs control on/off and select between three levels of brightness. A pulse-width modulation (PWM) signal can also be used to modulate LED brightness. The MAX1570 is available in 16-pin 4mm x 4mm Thin QFN packaging (0.8mm max height).

Key Features Excellent 0.3% LED-to-LED Current Matching 30mA/LED Drive Capability Proprietary 1x/1.5x Modes for Ultra-High Efficiency Low Input Ripple and EMI Eliminates Ballast Resistors Digital or PWM LED Dimming Control 0.1µA Shutdown Current 2.7V to 5.5V Supply Voltage Range Soft-Start Limits Inrush Current Thermal-Shutdown Protection No External Inductor, Schottky, or Zener Diode Required Tiny 16-Pin 4mm x 4mm Thin QFN Package

MAX1570: Typical Operating Circuit Applications/Uses Cell Phones/Smartphones Digital Cameras and Camcorders PDAs and Palmtop Computers Portable MP3 Players White LED Backlighting

DataSheet

Parametrics

Design kits & evaluation modules

• MAX1570EVKIT

Quality and Environmental Data

• MAX1570.pdf

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• MAX1848：White LED Step-Up Converter in SOT23

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