FAN5608

FAN5608 Serial / Parallel LED Driver with Current-Regulated, Step-Up DC/DC Converter

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FAN5608 Serial / Parallel LED Driver with Current-Regulated, Step-Up DC/DC Converter

August 2006

FAN5608 Serial / Parallel LED Driver with Current-Regulated, Step-Up DC/DC Converter
Features
Two independent channels drive up to six LEDs per channel Adaptive output voltage drive to maximize efficiency PFM mode of operation of the boost circuit Up to 85% efficiency Up to 2 20mA output Two built-in DACs for independent (digital) brightness control for both channels LED current can be duty-cycle-modulated, 0 to 20mA Digital, analog, and PWM brightness control 2.7V to 5.5V input voltage range 500KHz operating frequency Soft-start feature Low shutdown current: ICC 1A Open-load protection Minimal external components needed Space-saving 4x4mm 12-lead MLP packages

Description
The FAN5608 is an integrated Schottky diode LED driver, which generates regulated output currents from a battery input voltage of 2.7V to 5V. An internal MOS switch and the external inductor deliver the necessary voltage to the load. The proprietary internal compensation loop continuously monitors the lowest LED cathode voltage of both channels and adjusts the VOUT voltage to the minimum value. The minimum VOUT is determined by the highest LED forward voltage of the selected channel. This adaptive nature allows the FAN5608 architecture to deliver high efficiency. Up to twelve LEDs can be connected in series as long as the summed forward voltage does not exceed the maximum specification of 24V. It is not required to match an equal number of LEDs serially within each channel; FAN5608 delivers the highest efficiency and best current regulation in the balanced configuration. FAN5608 has two internal two-bit D/A converters that provide independent programmability to each output channel. In analog programming, "B"
pins must be GND (logic "0"); a resistor must be connected between pin "A" and a fixed supply voltage. The output current can be programmed to any desired value within the specified range. The FAN5608DHMPX is available in a 4x4mm 12-lead MLP package. A single external resistor sets the current and turns the device ON and OFF.

Applications
Cell phones Handheld computers PDAs, DSCs, MP3 players Keyboard backlights LED displays

Ordering Information
Part Number
FAN5608DHMPX

Pb-Free
Yes

Schottky Diode
Internal

Package
MLP-12 4x4mm

Packing Method
Tape and Reel

2006 Fairchild Semiconductor Corporation FAN5608 Rev. 1.0.5 8/8/06

www.fairchildsemi.com