8-String, White LED Driver with SMBus and
PWM Input for LCD Backlight Applications
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
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
28-lead, 4 mm × 4 mm × 0.75 mm LFCSP_WQ
Notebook PCs, UMPCs, and monitor displays
FUNCTIONAL BLOCK DIAGRAM
STEP-UP SWITCHING REGULATOR
EIGHT CURRENT SOURCES
PWM DUTY EXTRACTOR
8-BIT BRIGHTNESS CONTROL LOGIC
FIXED DELAY/NO DELAY DIRECT PWM/
DC CURRENT DIMMING CONTROL
WITH PWM AND/OR SMBus INTERFACE
INTERNAL SOFT START
AUTODISABLE FOR LED OPEN/SHORT
The ADD5203 is a white LED driver for backlight applications
based on high efficiency, current-mode, step-up converter tech-
nology. 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°C to +85°C.
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
©2010 Analog Devices, Inc. All rights reserved.