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A8514

Wide Input Voltage Range, High Efficiency Fault Tolerant LED Driver

Allegro MicroSystems 

A8514

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 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)

Package: 20-pin TSSOP with exposed

thermal pad (suffix LP)

Not to scale

Description

The A8514 is a multi-output white LED driver for small-size

LCD backlighting. It integrates a current-mode boost converter

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 A8514 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.

The A8514 can drive an external P-FET to disconnect the input

supply from the system in the event of a fault. The A8514

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 A8514 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 A8514 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

VIN

8 to 16 V

RSC

0.033 Ω

L1

D1

Q1

10 μH

2 A / 60 V

CIN

4.7 μF

50 V

RADJ

249 Ω

RC

20 Ω

CC

22 nF

VC

100 kΩ

CVDD

0.1 μF

RISET

8.25 kΩ

RFSET

10 kΩ

GATE

SW

VSENSE

VIN A8514

VDD

PAD

FAULT

PWM/EN

APWM

ISET

FSET/SYNC

OVP

LED1

LED2

LED3

LED4

COMP

AGND PGND

ROVP

137 kΩ

CP

120 pF

VOUT

COUT

4.7 μF

50 V

RZ

150 Ω

CZ

0.47 μF

A8514-DS, Rev. 4

Figure 1. Application with VIN to ground short protection, using P-MOSFET sensing

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