Evaluation Board For MAX1573 Fully Assembled And Tested Surface-Mount Circuit Board

The MAX1573 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 MAX1573 is available in the tiny chip-scale UCSP (4 x 4 grid) and 16-pin thin QFN packages.

• Proprietary Adaptive 1x/1.5x Modes
• High Efficiency (P_LEDs/P_BATT), 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