1 Features

1• Drives up to 3 Parallel High-Voltage LED Strings

at 40 V Each With up to 90% Efficiency

• 0.4% Typical Current Matching Between Strings

• 256 Level Logarithmic and Linear Brightness

Control With 14-Bit Equivalent Dimming

• I2C-Compatible Interface

• Direct Read Back of Ambient Light Sensor Via

8-bit ADC

• Programmable Dual Ambient Light Sensor Inputs

With Internal Sensor Gain Selection

• Dual External PWM Inputs for LED Brightness

Adjustment

• Independent Current String Brightness Control

• Programmable LED Current Ramp Rates

• 40-V Overvoltage Protection

• 1-A Typical Current Limit

2 Applications

• Power Source for White LED Backlit LCD Displays

• Programmable Keypad Backlight

3 Description

The LM3532 is a 500-kHz fixed frequency

asynchronous boost converter which provides the

power for 3 high-voltage, low-side current sinks. The

device is programmable over an I2C-compatible

interface and has independent current control for all

three channels. The adaptive current regulation

method allows for different LED currents in each

current sink thus allowing for a wide variety of

backlight and keypad applications.

The main features of the LM3532 include dual ambient light sensor inputs each with 32 internal

voltage setting resistors, 8-bit logarithmic and linear

brightness control, dual external PWM brightness

control inputs, and up to 1000:1 dimming ratio with

programmable fade in and fade out settings.

The LM3532 is available in a 16-pin, 0.4-mm pitch

thin DSBGA package. The device operates over a

2.7-V to 5.5-V input voltage range and the −40°C to

+85°C temperature range.