4ch PWM-Dimming LED Driver

New Product Bulletin
4ch PWM-Dimming LED Driver
BD9428
LED Driver for LCD Backlighting
Features Industry-Leading Efficiency
Product Outline
BD9428 contributes to save the power (high efficiency technology) of LED back light for LCD TV's or monitors.
4 channels of high voltage (up to 80V), high current capability (250mA/ch) LED current drivers are integrated.
By integrating these high V/I current source, customer can unify the design models for each size of LCD
DIP16 Package
panels. (Customer don't need to design one by one for each size of panels)
■ Supports a wide range of panel sizes
with high voltage capability and large
current capability
■ A high efficiency system
Features
VCC
Integrated 4ch (250mA/ch), 80V LED driver supports a wide range of
panel sizes
Conventional Method
Monitoring LED Supply Voltage
Audible noise reduction circuit is integrated
Anti inrush current by the soft start function
10V swing output can drive enternal MOSFET for DC/DC
Block Diagram
VIN
CIN
BD9428
CREG100
REG100
COUT
OUT
OSDET
VCC
CVCC
VCC
STB
REGULATOR
UVLO TSD
(VCC)
OVP SCP
FILTER
PWM COMP
RT
OSC
FAIL
REG100 10V Swing
N
Control
Logic
Control
Block
OVP
4
Patented
DRIVER
Current
Sense
3
Soft Start Control
SSFB
RSSFB
CSSFB
ERR AMP
2
Coil Noise
Reduction Circuit
up to 80V
high voltage
+
1
The voltage at the cathode of each LED line is monitored to
maintain a constant supply voltage at the lowest level to maximize
the efficiency
LED1
LED2
LED3
LED4
Current Driver
PWM
ISET
CS
Additio
nal
Loss
Conventional Method
Securing the output voltage to keep
enough margin to the fluctuation of the
LED's Vf
MAX
250mA/ch
ISET
GND
Open/Short
Detect
d
rove
Imp iency
c
i
f
Ef
ROHM Patented
Efficiency increased 10%
(Estimated)
LED supply voltage optimization
OSDET
U.S. Patent No. 7,235,954; 7,541,785; 7,944,189; 8,242,756
9th August,2013.
.56F6705E-A 08.2013
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