A8521
Wide Input Voltage Range, High Efficiency
Fault Tolerant LED Driver
Description
Features and Benefits
• AEC-Q100 Qualified
The A8521 is a multi-output white LED driver for small-size
• Wide input voltage range of 5 to 40 V for start/stop, cold
crank and load dump requirements
• Fully integrated LED current sinks and boost converter
with 60 V DMOS
• Sync function to synchronize boost converter switching
frequency up to 2.3 MHz, allowing operation above the
AM band
• Excellent input voltage transient response
• Single resistor primary OVP minimizes VOUT leakage
• Internal secondary OVP for redundant protection
• LED current of 80 mA per channel
• Drives up to 12 series LEDs in 4 parallel strings
• 0.7% to 0.8% LED to LED matching accuracy
• PWM and analog dimming inputs
• 5000:1 PWM dimming at 200 Hz
• Provides driver for external PMOS input disconnect switch
• Extensive protection against:
▫ Shorted boost switch or inductor
▫ Shorted FSET or ISET resistor
▫ Shorted output
▫ Open or shorted LED pin
▫ Open boost Schottky
▫ Overtemperature (OTP)
LCDbacklighting.Itintegratesacurrent-modeboostconverter
with internal power switch and four current sinks. The boost
converter can drive up to 48 LEDs, 12 LEDs per string, at
80 mA. The LED sinks can be paralleled together to achieve
even higher LED currents, up to 320 mA. The A8521 can
operate with a single power supply, from 5 to 40 V, which
allowstheparttowithstandloaddumpconditionsencountered
in automotive systems.
TheA8521candriveanexternalP-FETtodisconnecttheinput
supply from the system in the event of a fault. The A8521
provides protection against output short and overvoltage,
open or shorted diode, open or shorted LED pin, shorted
boost switch or inductor, shorted FSET or ISET resistor, and
IC overtemperature. A dual level cycle-by-cycle current limit
function provides soft start and protects the internal current
switch against high current overloads.
The A8521 has a synchronization pin that allows PWM
switching frequencies to be synchronized in the range of
580 kHz to 2.3 MHz. The high switching frequency allows
the A8521 to operate above the AM radio band.
Package: 20-pin TSSOP with exposed
thermal pad (suffix LP)
Continued on the next page…
Applications:
LCD backlighting or LED lighting for:
▫ Automotive infotainment
▫ Automotive cluster
▫ Automotive center stack
Not to scale
Typical Application Circuit
V
IN
D1
2 A / 60 V
R
L1
10 μH
SC
8 to 16 V
V
OUT
0.033 Ω
Q1
C
C
C
IN
R
C
R
OVP
22 nF
4.7 μF
C
OUT
4.7 μF
50 V
R
249 Ω
ADJ
20 Ω
137 kΩ
50 V
SW
GATE
VSENSE
OVP
V
C
VIN
VDD
A8521
C
VDD
100 kΩ
0.1 μF
PAD
LED1
LED2
LED3
LED4
COMP
FAULT
PWM/EN
APWM
ISET
R
Z
FSET/SYNC
AGND
C
P
120 pF
R
ISET
150 Ω
R
10 kΩ
FSET
8.25 kΩ
PGND
C
Z
0.47 μF
Figure 1. Application with VIN to ground short protection, using P-MOSFET sensing
A8521-DS
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