1 Features

1• Drives up to 2 Strings of 10 Series LEDs

• Wide 2.3-V to 5.5-V Input Voltage Range

• Up to 87% Efficient

• 8-bit I2C-Compatible Programmable Exponential

or Linear Brightness Control

• PWM Brightness Control for CABC Operation

• Independent Current Control per String

• True Shutdown Isolation for LEDs

• Internal Soft-Start Limits Inrush Current

• Adaptive Headroom

• Programmable 16-V/24-V/32-V/40-V Overvoltage

Protection

• Selectable Boost Frequency of 500 kHz or 1 MHz

with Optionally Additional Offset

• Low Profile 12-Pin DSBGA Package

• Solution Size 32 mm²

2 Applications

• Smart-Phone LCD Backlighting

• LCD and Keypad Lighting

3 Description

The LM3630A is a current-mode boost converter

which supplies the power and controls the current in up to two strings of 10 LEDs per string. Programming

is done over an I2C-compatible interface. The

maximum LED current is adjustable from 5 mA to

28.5 mA. At any given maximum LED current the

LED brightness is further adjusted with 256 exponential or linear dimming steps. Additionally,

pulsed width modulation (PWM) brightness control

can be enabled allowing for LED current adjustment

by a logic level PWM signal.

The boost switching frequency is programmable at

500 kHz for low switching loss performance or 1 MHz

to allow the use of tiny low-profile inductors. A setting for a 10% offset of these frequencies is available.

Overvoltage protection is programmable at 16 V,

24 V, 32 V, or 40 V to accommodate a wide variety of

LED configurations and Schottky diode/output

capacitor combinations.

The device operates over a 2.3-V to 5.5-V operating

voltage range and –40°C to +85°C ambient

temperature range. The LM3630A is available in an ultra-small 12-bump DSBGA package.