FAN5616 Datasheet, PDF (1/14 Pages) Fairchild Semiconductor – High-Efficiency, Constant-Current LED Driver with Adaptive Charge Pump

November 2005
FAN5616
High-Efficiency, Constant-Current LED Driver with
Adaptive Charge Pump
Features
■ 3-Channel Parallel LED Driver for a Large Range of
Forward Voltages
■ Adaptive V_OUT Adjustment to the Highest Diode
Forward Voltage
■ Internally Matched LED Current Sources
■ Matched LED Currents with Matched or Unmatched
LEDs
■ Built-in Charge Pump with Three Modes of Operation:
1x, 1.5x, and 2x
■ Up to 90% Efficiency
■ Up to 50kHz PWM Dimming Frequency
■ Low EMI, Low Ripple
■ Up to 120mA Output Current
■ Drives up to 3 LEDs at 40mA each
■ External Resistor to Set Maximum (100%) LED
Current
■ Built-in 2-bit DAC to Control LED Current in Digital
Mode
■ 2.5V to 5.5V Input Voltage Range
■ I_CC < 1µA in Shutdown Mode
■ 1MHz Operating Frequency
■ Shutdown Isolates Output from Input
■ Smart Soft-Start Limits In-Rush Current
■ Short Circuit Protection
■ Minimal External Components Needed
■ Available in a 3x3mm 16-lead MLP Package
Applications
■ Cell Phones
■ PDAs, DSCs, and MP3 Players
Description
The FAN5616 generates a regulated output current from
a battery with an input voltage between 2.7V to 5.5V.
Switch reconfiguration and fractional switching tech-
niques are utilized to achieve high efficiency over the
entire input voltage range. The adaptive nature of the
built-in charge pump eliminates the need for LED pre-
selection (matching) and ensures operation with high
efficiency. The driver's built-in, proprietary, auto-sense
circuitry ensures the same high efficiency regardless of
the number of LEDs. When the input voltage is suffi-
ciently high to sustain the LED’s programmed current
level, the FAN5616 reconfigures itself to operate as a lin-
ear regulator, and the charge pump is turned off.
The FAN5616 supports both digital and PWM LED
brightness control methods. The built-in 2-bit DAC offers
a selection of four LED current levels, each level is a per-
centage of the maximum LED current set by the external
R_SET resistor.
The FAN5616 includes built-in shutdown, short circuit
and thermal protection circuitry. A built-in smart soft-start
circuitry prevents excessive current draw during power
on while allowing for an increased PWM frequency for
dimming.
Minimal external components are required. Only two
0.1µF to 1µF bucket capacitors, a 4.7µF input capacitor
and a 1µF output capacitor are needed for proper opera-
tion.
The FAN5616 is available in a 3x3mm 16-lead MLP
package.
Ordering Information
Product Number
FAN5616
Package Type
3x3mm 16-Lead MLP
Order Code
FAN5616MPX
©2005 Fairchild Semiconductor Corporation
1
FAN5616 Rev. 1.0.0
www.fairchildsemi.com