Four-String, White LED Driver

for LCD Backlight Applications

Data Sheet

ADD5207

Rev. A

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FEATURES

White LED driver based on inductive boost converter

Integrated 40 V MOSFET with 1.5 A peak current limit

Input voltage range: 6 V to 21 V

Maximum output adjustable up to 36 V

600 kHz to 1 MHz adjustable operating frequency

Typical 39 V fixed overvoltage protection (OVP)

Built-in soft start for boost converter

Drives up to 4 LED current strings

LED current adjustable up to 25 mA for each channel

Headroom control to maximize efficiency

Fixed LED dimming frequency: 8 kHz

LED open fault protection

Brightness control with PWM input

Dimming controls

4-channel operation: 90 degree phase shift between

channels

3-channel operation: 120 degree phase shift between

channels

General

Thermal shutdown

Undervoltage lockout

14-lead, 4 mm × 3 mm LFCSP

APPLICATIONS

Notebook PCs, UMPCs, and monitor displays

GENERAL DESCRIPTION

The ADD5207 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, 1.5 A internal switch and a

pin-adjustable operating frequency between 600 kHz and 1 MHz.

The ADD5207 contains four regulated current sources for

uniform LED brightness. Each current source can drive up to

25 mA and the LED-driving current is pin adjustable by an

external resistor. The ADD5207 drives up to four parallel

strings of multiple series-connected LEDs with a ±1.5% current

matching between strings.

The ADD5207 provides phase shift PWM brightness control

methods. LED dimming control is achieved through the PWM

input. The device includes an 8 kHz LED-dimming oscillator

for driving each current source. The ADD5207 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 ADD5207 also has multiple safety protection features to

prevent damage during fault conditions. If any LED is open, the

device automatically disables the faulty current source. The

internal soft start circuit prevents a high inrush current during

startup. Thermal shutdown protection prevents thermal damage.

The ADD5207 is available in a low profile, thermally enhanced,

4 mm × 3 mm × 0.75 mm, 14-lead, RoHS-compliant lead frame

chip scale package (LFCSP) and is specified over the industrial

temperature range of −25°C to +85°C.

TYPICAL APPLICATION CIRCUIT

L1

10µH

VIN

6.8kΩ

2.2nF

180kΩ

C2

OPEN

10µF

ISET

COMP

GND

SW

D1

OVP

FB1

FB2

FB3

FB4

14

13

4

5

6

7

12

11

3

1

+

–

PWM

9

100kΩ

FSLCT

2

1µF

VDD

8

4µF

ADD5207

0.1µF

SHDN

OFF ON

10

Figure 1.