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.
Key Features
Applications/Uses
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
Notes: **This pricing is BUDGETARY, for comparing similar parts. Prices are in
U.S. dollars and subject to change. Quantity pricing may vary
substantially and international prices may differ due to local
duties, taxes, fees, and exchange rates. For volume-specific prices
and delivery, please see the price and availability page
or contact an authorized distributor.
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