DATASHEET SEARCH SITE | WWW.ALLDATASHEET.COM
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 6
Technical content
Four-String, White LED Driver for LCD Backlight Applications Preliminary Technical Data ADD5211 Rev. PrA Document Feedback 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. Trademarks and registered trademarks are the property of their respective owners. Tel: 781.329.4700 ©2013 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com
FEATURES
White LED driver based on an inductive boost controller Wide input voltage range: 4.5 V to 40 V Adaptive output voltage to minimize power dissipation Adjustable operating frequency: 200 kHz to 1.2 MHz Programmable UVLO Programmable soft start time for boost converter Programmable external MOSFET switching rising/falling time Drives up to 4 LED current sinks with internal MOSFETs Brightness control with PWM input Adjustable LED current: 40 mA up to 200 mA Headroom control to maximize efficiency LED dimming frequency: up to 25 kHz 1000:1 PWM dimming at 300 Hz Open drain fault indicator LED open and LED short fault protection Thermal shutdown Undervoltage lockout 24-lead, 4 mm × 4 mm LFCSP
APPLICATIONS
LCD monitor and TV LED backlights Industrial lighting GENERAL DESCRIPTION The ADD5211 is a 4 channel, white LED driver for backlight applications based on high efficiency, current mode, step-up converter technology. The boost controller drives an external MOSFET switch for step-up regulation from an input voltage of
4.5 V to 40 V and a pin adjustable operating frequency between
200 kHz and 1.2 MHz. An adjustable UVLO function is implemented to reduce input current during power-off. The ADD5211 contains four regulated current sinks for uniform brightness intensity. Each current sinks can be driven from 40 mA up to 200 mA and the LED driving current is pin adjustable by an external resistor. The ADD5211 with an input PWM interface drives up to four parallel strings of multiple series connected LEDs with ±1.5% current matching between strings. Additional features include fault indicator output LED short protection, LED open protection, boost output short protection, overvoltage protection, cycle-by-cycle current limit, and thermal shutdown for both the IC and LED array. The programmable soft start is implemented to reduce inrush current during startup. TYPICAL APPLICATION 10555-001 VINUVLO GATE_P GATE_N OFF ON EN ISET LSD VDD FAULT PWM VDR LGND OVP FB4 FB3 FB2 FB1 PGND RAMP CS FREQ COMPAGND SS ADD5211 VIN Figure 1.
ADD5211 Preliminary Technical Data Rev. PrA | Page 2 of 6 DETAILED FUNCTIONAL BLOCK DIAGRAM ADD5211 10555-002 COMP VIN EN UVLO VDD PWM FREQ AGND FAULT OVP VDR SS GATE_P CS LGND LSD PGND GATE_N RAMP OVP FB_REF BOOST CONTROL FB_MIN ERROR AMP PWM COMP gm OSC RAMP SOFT START CURRENT SENSE R S Q R VDR SWITCH DRIVER DCOMP DREF START-UP OVP REF OVP SCP FAULT DETECTOR THERMAL SHUTDOWN POR OPEN STRING DETECTOR SHORT STRING DETECTOR UNUSED STRING DETECTOR OVP POR ×10 LINEAR REGULATOR BANDGAP REFERENCE VOLTAGE REFERENCE POR UVLO DETECTOR DEVICE ENABLE CONTROL LOGIC START-UP BOOST CONTROL DIMMING CONTROL DIMMING CONTROL BOOST SCP REF THERMAL SHUTDOWN BOOST SHORT 500kΩ VDD CURRENT SOURCE FB1 FB2 FB3 FB4 500kΩ AGND AGND STRING VOLTAGE DETECTOR FB_MIN CURRENT SOURCE1 CURRENT SOURCE2 REF CURRENT SOURCE3 ISET Figure 2.
TA = 25°C, unless otherwise noted. soldered in a circuit board for surface-mount packages. Table 2. Thermal Resistance
- CONNECT THE EXPOSED PADDLE TO GROUND.
Figure 3. Pin Configuration Table 3. Pin Function Descriptions 1 VDR Switching MOSFET Gate Driver Supply Pin. through a voltage divide resistor.
4 EN Shutdown Control Pin for PWM Input
6 FAU LT Open Drain Fault Output. regulator provides power to the ADD5211. pin. If unused, connect FB1 to LGND. pin. If unused, connect FB2 to LGND. 15 LGND LED Current Sink Ground. pin. If unused, connect FB3 to LGND. pin. If unused, connect FB4 to LGND. with voltage divide resistors. 20 RAMP Ramp Compensation Pin. 22 GATE_N Switching MOSFET Gate Low Driving Pin. 23 GATE_P Switching MOSFET Gate High Driving Pin.
22 LEDs/CH, 100mA/CH
Figure 4. Typical Four-String Application Circuit Figure 5. Typical Two-String Application Circuit
COMPLIANT TO JEDEC STANDARDS MO-220-WGGD.
0.05 MAX
0.02 NOM
0.20 REF
0.25 MIN
Figure 6. 24-Lead Lead Frame Chip Scale Package [LFCSP_WQ] registered trademarks are the property of t heir respective owners.