Download AD5203设计的8串白光LED驱动方案

AD5203 设计的 8 串白光 LED 驱动方案
作者：summao 来源：本站整理 发布时间：2010-6-8 15:20:40 [收 藏] [评 论]
AD5203 是 ADI 公司的集成了 SMBus 和 PWM 输入的 8 串白光 LED(WLED)驱动器,采用电流模式和升压转
换器技术,具有高效率.AD5203 集成了 0.15 Ω, 2.9 A 的开关,工作频率在 350kHz 和 1MHz 间选择.输入电压
从 6V 到 21V,最大输出电压可调至 45V,调光频率在 200Hz 到 10kHz 间可调,具有 LED 开路和短路故障保护.
主要用在笔记本电脑,UMPC 和监视显示器.本文介绍了 AD5203 主要特性,方框图以及采用无延迟调光模式
的 SMBus 接口, DPWM 调光模式的 PWM 接口和 DC 电流调光模式的 PWM 接口的典型应用电路.
8-String, White LED Driver with SMBus and PWM Input for LCD Backlight Applications
The ADD5203 is a white LED driver for backlight applications based on high efficiency, current-mode,
step-up converter technology. It is designed with a 0.15 Ω, 2.9 A internal switch and a pin-adjustable
operating frequency between 350 kHz and 1 MHz. The ADD5203 contains eight regulated current
sources for uniform brightness intensity. Each current source can be driven up to 30 mA, and the LED
driving current is pin adjustable by an external resistor. The ADD5203 drives up to eight parallel strings
of multiple series connected LEDs with a ±1.5% current matching between strings. The ADD5203 provi
des various dimming modes. Each dimming mode is selectable with an external dimming mode selection
pin. The LED dimming control interface can be achieved through PWM input and/or SMBus.The device
provides adjustable output dimming frequency range from 200 Hz to 10 kHz by an external resistor and
capacitor. The ADD5203 operates over an input voltage range of 6 V to 21 V, but the device can functi
on with a voltage as low as 5.6 V. The ADD5203 also has multiple safety protection features to prevent
damage during fault conditions. If any LED is open or short, the device automatically disables the
faulty current source. The internal soft start prevents inrush current during startup. Thermal shutdown prot
ection prevents thermal damage.
The ADD5203 is available in a low profile, thermally enhanced, 4 mm × 4 mm × 0.75 mm, 28-lead, R
oHS-compliant lead frame chip scale package (LFCSP_WQ) and is specified over the industrial temperatu
re range of −25℃ to +85℃.
AD5203 主要特性:
White LED driver based on inductive boost converter
Integrated 50 V MOSFET with 2.9 A peak current limit
Input voltage range: 6 V to 21 V
Maximum output adjustable up to 45 V
350 kHz to 1 MHz adjustable operating frequency
Overvoltage protection (OVP) up to typical 47.5 V
Built-in soft start for boost converter
Drives up to eight LED current strings
LED current adjustable up to 30 mA for each channel
Headroom control to maximize efficiency
Adjustable dimming frequency: 200 Hz to 10 kHz
LED open and short fault protection
Selectable dimming control interface methods
PWM input
SMBus serial input
Selectable dimming modes
Fixed delay PWM dimming control with 8-bit resolution
No delay PWM dimming control with 8-bit resolution
Direct PWM dimming control
DC current dimming control with 8-bit resolution
General
Thermal shutdown
Undervoltage lockout
28-lead, 4 mm × 4 mm × 0.75 mm LFCSP_WQ
AD5203 应用:
Notebook PCs, UMPCs, and monitor displays
图 1.AD5203 电路方框图
图 2.AD5203 典型应用电路:采用无延迟调光模式的 SMBus 接口
图 3.AD5203 典型应用电路:采用 DPWM 调光模式的 PWM 接口
图 4.AD5203 典型应用电路:采用 DC 电流调光模式的 PWM 接口