A8502KLPTR-T Datasheet, PDF (1/35 Pages) Allegro MicroSystems – Wide Input Voltage Range, High Efficiency Fault Tolerant LED Driver

A8502
Wide Input Voltage Range, High Efficiency
Fault Tolerant LED Driver
Features and Benefits
• AEC-Q100 qualified
• 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 V_OUT leakage
• Internal secondary OVP for redundant protection
• LED current of 120 mA per channel
• Drives up to 12 series LEDs in 2 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 optional 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)
Package: 16-pin TSSOP with exposed
thermal pad (suffix LP)
Not to scale
Description
The A8502 is a multi-output white LED driver for small-size
LCD backlighting. It integrates a current-mode boost converter
with internal power switch and two current sinks. The boost
converter can drive up to 24 LEDs, 12 LEDs per string, at
120 mA. The LED sinks can be paralleled together to achieve
even higher LED currents, up to 240 mA. The A8502 can
operate with a single power supply, from 5 to 40 V, which
allows the part to withstand load dump conditions encountered
in automotive systems.
If required, the A8502 can drive an external P-FET to
disconnect the input supply from the system in the event of
a fault. The A8502 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 A8502 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 A8502 to operate above the AM radio band.
Continued on the next page…
Applications:
LCD backlighting or LED lighting for:
▫ Automotive infotainment
▫ Automotive cluster
▫ Automotive center stack
Typical Application Circuit
V_IN
10 to 14 V
R_SC
0.033 Ω
L1
D1
Q1
10 μH
2 A / 60 V
C_IN
4.7 μF
50 V
R_ADJ
249 Ω
R_C
20 Ω
C_C
22 nF
V_C
100 kΩ
C_VDD
0.1 μF
GATE
SW
VSENSE
VIN _A8502
VDD
PAD
OVP
LED1
R_OVP
137 kΩ
R_ISET
8.25 kΩ
R_FSET
10 kΩ
FAULT
PWM/EN
APWM
ISET
FSET/SYNC
AGND
LED2
COMP
PGND
C_P
120 pF
V_OUT
C_OUT
4.7 μF
50 V
R_Z
120 Ω
C_Z
0.47 μF
Figure 1. Application with VIN to ground short protection, using optional P-MOSFET sensing
A8502-DS, Rev. 3