19-0865; Rev 0; 8/07
Highest Efficiency Supply for 2 to 6 Series WLEDs in a 2mm x 2mm TDFN Package
www.datasheet4u.com
...
19-0865; Rev 0; 8/07
Highest Efficiency Supply for 2 to 6 Series WLEDs in a 2mm x 2mm TDFN Package
www.datasheet4u.com
KIT ATION EVALU E L B AVAILA
General Description
♦ High Efficiency, Up to 91% ♦ 2.6V to 5.5V Input
Voltage Range ♦ Fixed-Frequency Operation
Features
MAX8901A/MAX8901B
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 over
voltage protection, WLED over
voltage 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 under
voltage lockout (...