FAN5608_06 Datasheet, PDF (1/13 Pages) Fairchild Semiconductor – 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
ƒ Two independent channels drive up to six LEDs
per channel
ƒ Adaptive output voltage drive to maximize efficiency
ƒ PFM mode of operation of the boost circuit
ƒ Up to 85% efficiency
ƒ Up to 2×20mA output
ƒ Two built-in DACs for independent (digital) brightness
control for both channels
ƒ LED current can be duty-cycle-modulated, 0 to 20mA
ƒ Digital, analog, and PWM brightness control
ƒ 2.7V to 5.5V input voltage range
ƒ 500KHz operating frequency
ƒ Soft-start feature
ƒ Low shutdown current: I_CC< 1μA
ƒ Open-load protection
ƒ Minimal external components needed
ƒ Space-saving 4x4mm 12-lead MLP packages
Applications
ƒ Cell phones
ƒ Handheld computers
ƒ PDAs, DSCs, MP3 players
ƒ Keyboard backlights
ƒ LED displays
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
V_OUT voltage to the minimum value. The minimum V_OUT
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.
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