SGM3122

SGM3122 White LED Charge Pump Current Source with PWM Brightness Control GENERAL DESCRIPTION The SGM3122 is a charge pump with PWM brightness control for white LED supplies in LCD display backlight applications. The supply voltage ranges from 2.7V to 5.5V, it is ideally suited for all applications powered by a single Li-ion battery cell or three to four NiCd, NiMH, or alkaline battery cells. The device provides a constant current for each LED, and the initial current value can be set by an external resistor. High efficiency is achieved by utilizing a 1×/1.5× fractional conversion technique in combination with very low dropout current sources. The SGM3122 is capable of driving up to four channels of LEDs at 30mA per channel from a 2.7V to 5.5V input. Additionally, the current controlled charge pump ensures low input current ripple and EMI. A low external part count (two 0.47µF flying capacitors and two small 1µF capacitors at VIN and VOUT) makes this part ideally suited for small, battery-powered applications. The SGM3122 is available in a Green TQFN-3×3-16L package, and is rated over the -40°C to +85°C temperature range. FEATURES  Input Voltage Range: 2.7V to 5.5V  Drives up to 4 LEDs at 30mA Each  LED Brightness Control Through PWM Control Signal  High Efficiency by Fractional Conversion with 1× and 1.5× Modes  Switching Frequency: 1MHz  Regulated Output Current with 0.5% Matching  Internal Soft-Start Limits Inrush Current  Low Input Ripple and Low EMI  Over-Curre...