The MAX1573ETE fractional charge pump drives up to four white LEDs with regulated constant current for uniform intensity. By utilizing proprietary adaptive 1x/1.5x modes and ultra-low-dropout current regulators, it maintains the highest possible efficiency over the full 1-cell Li+ battery input voltage range. The 1MHz fixed-frequency switching allows for tiny external components and 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 amongst three levels of brightness. A pulse-width modulation (PWM) signal can also be used to modulate LED brightness, requiring no additional components. The MAX1573ETE is available in the tiny chip-scale UCSP (4 x 4 grid) and 16-pin thin QFN packages.
Feature
- Proprietary Adaptive 1x/1.5x Modes
- High Efficiency (PLEDs/PBATT), Up to 92%
- 0.2% LED Current Matching
- 28mA/LED Drive Capability
- Low Input Ripple and EMI
- Eliminates Ballast Resistors
- Logic or PWM Dimming Control
- Low 0.1μA Shutdown Current
- 2.7V to 5.5V Input Voltage Range
- Soft-Start Limits Inrush Current
- Output Overvoltage Protection
- Thermal Shutdown Protection
- No External Schottky Diode Required
- Tiny UCSP (2.1mm x 2.1mm x 0.6mm) and Thin QFN (4mm x 4mm) Packages
Applications
- Cell Phones/Smartphones
- MP3 Players
- Other Handhelds with Color Displays
- PDAs, Digital Cameras, and Camcorders
