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.