The LM3508 is a synchronous boost converter (no external Schottky diode required) that provides a constant current output. It is designed to drive up to 4 series white LEDs at 30mA from a single-cell Li-Ion battery. A single low power external resistor is used to set the maximum LED current. The LED current can be adjusted by applying a PWM signal of up to 100kHz to the DIM pin. Internal soft-start circuitry is designed to eliminate high in-rush current at start-up. For maximum safety, the device features an advanced short-circuit protection when the output is shorted to ground. Additionally, over-voltage protection and an 850kHz switching frequency allow for the use of small, low-cost output capacitors with lower voltage ratings. During shutdown, the output is disconnected from the input preventing a leakage current path through the LEDs to ground. The LM3508 is available in a tiny 9-bump chip-scale DSBGA package.

• Drives 4 Series White LEDs with up to 30mA
• >80% Peak Efficiency
• Up to 100kHz PWM Brightness Control
• Accurate ±5% LED Current Regulation across VIN range
• Internal Synchronous PFET (No Schottky Diode Required)
• True Shutdown Isolation
• Output Short-Circuit Protection
• 17.5V Over-Voltage Protection
• Internal Soft-Start Eliminates Inrush Current
• Wide Input Voltage Range: 2.7V to 5.5V
• 850kHz Fixed Frequency Operation
• Low Profile 9-Bump DSBGA Package (1.514mm x 1.514mm x 0.6mm)