The MAX1570ETE fractional charge pump drives up to five white LEDs with regulated constant current for uniform intensity. The MAX1570ETE 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 MAX1570ETE 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 MAX1570ETE is available in 16-pin 4mm x 4mm Thin QFN packaging (0.8mm max height).
Feature
- 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
Applications
- Cell Phones/Smartphones
- Digital Cameras and Camcorders
- PDAs and Palmtop Computers
- Portable MP3 Players
- White LED Backlighting
