1 Features

1• Drives Three Parallel High-Voltage LED Strings

for Display and Keypad Lighting

• High-Voltage Strings Capable of up to 40-V

Output Voltage and up to 90% Efficiency

• Up to 30-mA per Current Sink (Both Backlight and

Indicator)

• 11-Bit High-Voltage LED Dimming

• PWM Input for Content Adjustable Brightness

Control (CABC)

• Integrated 1-A/40-V MOSFET

• Adaptive Boost Output to LED Voltages

• Six Low-Voltage Current Sinks for Indicator LEDs

• Integrated Charge Pump for Improved Efficiency

and V IN Operating Range

• Internal Pattern Generation Engine for Each

Indicator LED

• Fully Configurable LED Grouping and Control

• Four Programmable Overvoltage Protection

Thresholds (16 V, 24 V, 32 V, and 40 V)

• Programmable 500-kHz and 1-MHz Switching

Frequency

• Overcurrent Protection

• Thermal Shutdown Protection

• 27 mm2 Total Solution Size

2 Applications

• Power Source for Smart Phone Illumination

• Display, Keypad and Indicator Illumination

• RGB Indicator Driver

3 Description

The LM3633 11-bit LED driver provides high-

performance backlight dimming for 1, 2, or 3 parallel

high-voltage LED strings while delivering up to 90%

efficiency. The boost converter with integrated 1-A,

40-V MOSFET automatically adjusts to LED forward

voltage to minimize headroom voltage and effectively

improve LED efficiency.

The LM3633 is a complete power source for

backlight, keypad, and indicator LEDs in smartphone

handsets. The high-voltage inductive boost converter

provides the power for three parallel LED strings (HVLED1, HVLED2 and HVLED3). The integrated

charge pump provides the bias for the six low-voltage

indicator LEDs (LVLED1-LVLED6). All low-voltage

current sinks can have a programmable pattern

modulated onto their output current for a wide variety

of blinking patterns.

An additional feature is a Pulse Width Modulation

(PWM) control input for content adjustable backlight

control, which can be used to control any high-

voltage current sink.

The LM3633 is fully programmable via an I2C-

compatible interface. The device operates over a 2.7-

V to 5.5-V input voltage range and a −40°C to 85°C

temperature range.