|
WillSEMI |
WD3138
White LED Driver with Digital and PWM
Brightness Control in Tiny Package
WD3138
Http//:www.sh-willsemi.com
With a 40-V rated integrated power switch MOSFET,
the WD3138 is a boost converter that drives up to 10
White LEDs in series. The WD3138 operates at
600kHz fixed switching frequency to reduce output
ripple, improve conversion efficiency, and allows for
the use of small external components.
The default Full-Scale White LED current is set by an
external sensor resistor with regulated 200mV
feedback voltage, as shown in typical application.
During operation, the LED current can be controlled
using the 1-wire digital interface through EN pin.
Alternately, a Pulse Width Modulation (PWM) signal
can also be applied on the EN pin, through which the
PWM Duty-Cycle determines the feedback reference
voltage and then the White LED current. In either
1-Wire digital or PWM mode, the WD3138 does not
burst the LED current; therefore, it does not generate
audible noises on the ceramic output capacitor. For
maximum protection, the device features integrated
open LED protection that disables the WD3138 to
prevent the output voltage from exceeding the
absolute maximum ratings during open LED
conditions.
The WD3138 is available in a PCB space saving DFN
2mm x 2mm-6L Package with bottom thermal pad.
Standard product is Pb-free and Halogen-free.
FB 1
COMP 2
GND 3
6 VIN
5 EN
4 LX
DFN 2mm x 2mm-6L
Pin configuration (Top view)
B38D
Y
W
Marking
= Device Code
= Year Code
= Week Code
Order information
Device
Package
Shipping
WD3138D-6/TR DFN-2x2-6L 3000/Reel&Tape
Features
2.7V~5.5V Input voltage range
38V Open LED Protection
200mV Reference Voltage
600kHz Switching frequency
Up to 91% Efficiency
Flexible Digital and PWM Brightness Control
PWM Dimming Duty ranges from 1% to 100%
Built-in Soft-Start and Over-Current limit
Applications
Smart Phones
Tablets
Portable games
Will Semiconductor Ltd.
1 Jun, 2015 - Rev. 1.0
Typical applications
WD3138
L1 D1
VIN 10μH~22μH WSB5543W VOUT
CIN
1μF
VIN LX
ON/OFF
Dimming Control
EN
GND
COMP
FB
COUT
1μF/50V
CCOMP
220nF
10 LEDs
RSET
Pin descriptions
Symbol
FB
COMP
GND
LX
EN
VIN
Thermal Pad
Pin No.
1
2
3
4
5
6
Bottom
Descriptions
Feedback pin for LED current. Connect the sense resistor from FB to
GND
Output of the Error Amplifier. Connect an external capacitor to this pin
to compensate the converter
Ground
Switch pin. Connect the inductor between VIN and LX. This pin is also
used to sense output voltage for Open LED Protection
Enable pin of boost converter. It also can be used for PWM and digital
dimming control
Power supply. Connect VIN to a supply voltage between 2.7V and 5.5V
The exposed thermal pad should be soldered to the analog ground
plane. If possible, use the thermal via to connect to ground plane
Will Semiconductor Ltd.
2 Jun, 2015 - Rev. 1.0
|