LM2796 Datasheet | National Semiconductor

Description The LM2796 is a charge-pump based white-LED driver that is ideal for mobile phone display backlighting. It can drive up to 7 LEDs in parallel with up to 20m A through each LED. Regulated internal current sources deliver excellent current and brightness matching in all LEDs. The LED-driver current sources are split into two independently controlled groups. The primary group (4 LEDs) can be used to backlight the main phone display. The second group (3 LEDs) can be used to backlight a secondary display or to provide other lighting features (keypad LEDs, for example). Brightness of the two groups can be adjusted independently with pulsewidth modulated (PWM) digital signals. The LM2796 works off an extended Li-Ion input voltage range (2.7V to 5.5V). Voltage boost is achieved with a highefficiency 3/2x-gain charge pump. The LM2796 is available in National’s chip-scale 18-bump micro SMD package. Features n Drives up to 7 LEDs with up to 20m A each n LEDs controlled in 2 Distinct Groups, for Backlighting 2 Displays (main LCD and sub-LCD) n Excellent Current and Brightness Matching n High-Efficiency 3/2x Charge Pump n Extended Li-Ion Input: 2.7V to 5.5V n PWM Brightness Control: 100Hz - 1k Hz n 18-bump Thin Micro SMD Package: (2.1mm x 2.4mm x 0.6mm) Applications n n n n Mobile Phone Display Lighting Mobile Phone Keypad Lighting PDAs General LED Lighting Typical Application Circuit © 2004 National Semiconductor Corporation DS200938 .national. Connection Diagram 18-Bump Thin Micro SMD Package, Large Bump NS Package Number TLA18 Pin Description Pin #s C1 D2 A3 A1, B2, A5, E1 A7 D6, E5, D4, E3 C5, B4, C3 B6 Pin Names VIN GND POUT C1+, C1-, C2+, C2EN D1A, D2A, D3A, D4A D1B, D2B, D3B EN-A Ground Charge pump output. Approximately 1.5x VIN Flying capacitor connections. Enable pin. Logic input. High = normal operation, Low = shutdown (charge pump and all current sources OFF). LED Outputs - Group A LED Outputs - Group B Enable for Group-A...