A8503
High Efficiency 6-Channel, 2 MHz, WLED/RGB Driver for
Medium Displays, with Integrated 55 V Power Switch
Description
Features and Benefits
▪ Active current sharing between LED strings for ±0.6%
accuracy and matching
The A8503 is a multi-output WLED/RGB LED driver for
medium-size LCD backlighting. It integrates a current-mode
boost converter with internal power switch and six current
sinks. The boost converter can provide output voltages up to
47 V. The boost converter can drive up to 72 LEDs at 20 mA
per LED with a battery voltage down to 5 V. The LED sinks
are capable of sinking up to 32 mA each, and can also be
paralleled together to achieve even higher LED currents. The
A8503 provides protection against overvoltage, open diode,
open or shorted LED string, and overtemperature. A dual
level cycle-by-cycle current limit function provides soft start
and protects against overloads. A soft start timeout monitor is
provided to enhance protection when starting up into a fault
condition.
▪ Drives up to 12 series × 6 parallel = 72 LEDs (Vf = 3.2 V,
If = 20 mA) at 5 V
▫ Each individual current sink is capable of 32 mA
▫ Adjustable overvoltage protection (OVP)
▪ 600 kHz to 2 MHz adjustable switching frequency
▫ Open or shorted LED string protection
▫ Open Schottky diode protection
▫ Overtemperature, cycle-by-cycle current limit,
undervoltage, and soft start time-out protections
▫ Selectable latched/auto-restart protection modes
▪ No audible MLCC noise during PWM dimming
▪ No pull-up resistors required for LED modules that use
ESD capacitors
When the MODE pin is set low, the A8503 latches on a fault,
and can be re-enabled only by cycling the input voltage, VIN,
or by toggling the EN pin. Connecting the MODE pin high
provides auto-restart after fault events. The A8503 features
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Package: 26 contact MLP/QFN (suffix EC)
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Applications
▪ Notebook and sub-notebook displays
▪ LCD monitors
▪ LCD panels
Approximate size
Typical Application
VBAT
5 to 22 V
D1
C
4.7 μF
35 V
L1
10 μH
BAT
R
C
OVP
OUT
2.2 μF
V
IN
4.3 to 5.5 V
SW SW
OVP
VIN
R
PULLUP
C
IN
0.1 μF
FAULT
FAULT
FSET
A8503
LED1
R
C
FSET
LED2
LED3
LED4
LED5
LED6
PAD
COMP
COMP
1 μF
EN
EN
Shutdown Enable
Off Off Off On Off
MODE
PWM
PWM
ISET
AGND PGND PGND DGND LGND
LED State
R
ISET
Figure 1. Typical application circuit
8503-DS