• 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

• Smart-Phone LCD Backlighting
• LCD and Keypad Lighting

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.