原标题：Allegromicro A8514多输出白光LED驱动方案

　　Allegromicro公司的A8514是用于小型LCD背光的多输出白光LED驱动器,集成了带功率开关的电流模式升压转换器和四个电流沉.升压转换器能以80mA驱动多达48个LED,每串12个LED.LED沉并联能提供更高电流,多达320mA.器件工作电压5V-40V,开关频率高达2.3MHz,每串LED匹配电流精度0.7% - 0.8%,PWM和模拟调光输入,主要用在汽车信息娱乐系统,汽车仪表盘和汽车中心操控区.本文介绍了A8514主要特性和优势, 方框图,以及多种应用电路.

　　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.

　　A8514主要特性和优势:

　　• 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

　　• 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)

　　A8514应用:

　　LCD backlighting or LED lighting for:

　　▫ Automotive infotainment

　　▫ Automotive cluster

　　▫ Automotive center stack

　　图1.A8514方框图

　　图2.A8514采用P-MOSFET检测和VIN接地短路保护的应用电路图

　　图3.A8514设计案例电路图

　　图4.A8514采用精密输入电流检测和VSENSE接地保护的SEPIC配置应用电路图