A8507 Datasheet, PDF (1/16 Pages) Allegro MicroSystems – LED Backlight Driver for LCD Monitors and Televisions

A8507
LED Backlight Driver for LCD Monitors and Televisions
Features and Benefits
▪ Fixed frequency current mode control with integrated
gate driver
▪ Each individual current sink is capable of 80 mA
▪ Adjustable overvoltage protection (OVP)
▪ Active current sharing between LED strings for ±0.6%
accuracy and matching
▪ 250 kHz to 1 MHz adjustable switching frequency
▪ Open or shorted LED string protection
▪ Overtemperature, cycle-by-cycle current limit, and
undervoltage protection
▪ No audible MLCC noise during PWM dimming
▪ No pull-up resistors required for LED modules that use
ESD capacitors
▪ SOIC 24-pin package for easy single-side PCB
manufacturing or TSSOP 24-pin package with exposed
thermal pad for better thermal performance
Packages:
Description
The A8507 is a multi-output WLED/RGB driver for
backlighting LCD monitors and televisions. The A8507
integrates a boost controller to drive external MOSFET and
six internal current-sinks. The boost converter is constant
frequency current mode converter.
PWM dimming allows LED currents to be controlled in 500:1
ratio. The LED sinks are capable of sinking up to 80 mA
each, and can be paralleled together to achieve even higher
currents.
The A8507 provides protection against overvoltage, open or
shorted LED string, and overtemperature. A dual level cycle-
by-cycle current limit function provides soft start and protects
against overloads.
The device is provided in a 24-pin SOICW package (LB), with
internally fused pins for enhanced thermal dissipation, and a
24-pin TSSOP package (LP), with an exposed thermal pad
for enhanced thermal dissipation. Both packages are lead (Pb)
free, with 100% matte tin leadframe plating.
24-pin TSSOP
with exposed thermal pad
(Package LP)
Not to scale
24-pin SOICW
with internally fused pins
(LB package)
Functional Block Diagram
V_BAT
4.7 μF
P
10 μH
DRIVER
2.2 μF
R_SC ^P
P
SENP SENN
R_OVP
OVP
R_FSET
FSET
OSC
Current Mode
Boost
Controller
Overvoltage
Protection
C_COMP
OCP SS
Ref
COMP
R_ISET
ISET
PWM
100 kΩ
+5 V
10 kΩ
EN
VIN
0.1 μF
Control
Logic/
UVLO
TSD
OVP
OCP
Control and ⁶
Feedback
Reference
Current
LED Select
6
Logic
Open/Short
6
LED Detect
LED1
LED2
LED3
LED4
LED5
FAULT
LED6
PGND
P
LP Only
LB Only
GND GND PAD LGND LGND
A8507-DS, Rev. 2
Figure 1. Functional block diagram
showing 6 parallel strings with 9 series
LEDs per channel