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 provides 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 function 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 protection prevents thermal damage.
The ADD5203 is available in a low profile, thermally enhanced, 4 mm × 4 mm × 0.75 mm, 28-lead, RoHS-compliant lead frame chip scale package (LFCSP_WQ) and is specified over the industrial temperature 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