The MAX8901A/MAX8901B step-up converters drive from two to six series-connected white LEDs (WLEDs) with constant current to provide uniform WLED intensity for LCD backlighting in cell phones, PDAs, and other handheld devices. The MAX8901_ operate at a fixed 750kHz (typ) switching frequency, allowing for tiny external components, and are optimized for the highest possible efficiency over the full 1-cell Li+/Li-Poly battery range.
These converters use a single input (ON) to enable the IC and to control WLED intensity. The MAX8901A requires a direct PWM input to regulate WLED intensity with the WLED current proportional to the PWM duty cycle. The MAX8901B uses single-wire, serial-pulse dimming that reduces the WLED intensity in 32 linear steps. Full-scale WLED current for serial-pulse dimming is 24.75mA (MAX8901B, 0.75mA/step).
The MAX8901_ features an internal soft-start to eliminate inrush currents during startup, input overvoltage protection, WLED overvoltage protection, and a shutdown mode with 0.01µA (typ) shutdown current. No WLED current is present in shutdown provided the WLED forward voltage is greater than the input supply voltage. Additional features include undervoltage lockout (UVLO) and thermal shutdown.
The MAX8901_ are available in tiny 8-pin, 2mm x 2mm TDFN-EP packages (0.8mm max height).
Key Features
Applications/Uses
High Efficiency, Up to 91%
2.6V to 5.5V Input Voltage Range
Fixed-Frequency Operation
Supplies from 2 to 6 WLEDs with 1.3% LED Current Accuracy
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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