1FEATURES

2• Single Chip White LED Flash and Backlight

Driver

• 1.5A Flash LED Current

• Dual String Backlight Control (40V Max VOUT)

• 128 Level Exponential and Linear Brightness

Control

• PWM Input for CABC

• Programmable Over-Voltage Protection

(Backlight)

• Programmable Current Limit (Flash)

• Programmable Switching Frequency

• Optimized Flash Current During Low-Battery

Conditions

APPLICATIONS

• White LED Backlit Display Power

• White LED Camera Flash Power

DESCRIPTION

The LM3639A is a single-chip white LED Camera

Flash Driver + LCD Display Backlight Driver. The lowvoltage,

high-current flash LED driver is a

synchronous boost which provides the power for a

single flash LED at up to 1.5A or dual LEDs at up to

750 mA each. The high-voltage backlight driver is a

dual-output asynchronous boost which powers dual

LED strings at up to 40V and 30 mA per string. An

adaptive regulation method in both boost converters

regulates the headroom voltage across the respective

source/sink to ensure the LED current remains in

regulation while maximizing efficiency. The

LM3639A's flash driver is a 2MHz or 4MHz fixed-

frequency synchronous boost converter plus 1.5A

constant current driver for a high-current white LED.

The high-side current source allows for grounded

cathode LED operation providing Flash current up to

1.5A. An adaptive regulation method ensures the

current source remains in regulation and maximizes

efficiency.

The device is controlled by an I2C-compatible

interface. Features for the flash LED driver include a

hardware flash enable (STROBE) allowing a logic

input to trigger the flash pulse, and a TX input for

synchronization to RF power amplifier events or other

high current conditions. Features for the LCD

backlight driver include a PWM input for content

adjustable backlight control, 128 exponential or linear

brightness levels, programmable over-voltage

protection, and selectable switching frequency (500

kHz or 1 MHz).

The device is available in a tiny 1.790 mm x 2.165

mm x 0.6 mm 20-bump, 0.4 mm pitch DSBGA

package and operates over the −40°C to +85°C

temperature range.