LM27953 Datasheet | National Semiconductor

Description The LM27953 is a charge-pump-based white-LED driver that is ideal for mobile phone display backlighting. It is intended to drive 4 LEDs for a main phone display backlight. Regulated internal current sources deliver excellent current and brightness matching in all LEDs. The LED driver current sinks can be used to backlight a main phone display with up to 4 LEDs. The low-side current drivers acmodate mon-anode-type LEDs. The current sinks can also drive standard two-terminal LEDs, and provide other general lighting functions (keypad lighting, fun lighting, etc). The brightness of the LEDs can be adjusted independently with an external resistor. The LM27953 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 LM27953 is available in National’s chip-scale 18-bump micro SMD package. Features n Drives 4 Individual mon-Anode LEDs with up to 20m A each for a Main Display Backlight n Independent Resistor-Programmable Current Setting 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 DS201280 .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 D6, E5, D4, E3 C5, B4, C3 B6 Pin Names VIN PWR GND PWR POUT C1+, C1-, C2+, C2D1, D2, D3, D4 SIG POUT EN Power Ground Charge pump output. Approximately 1.5x VIN Flying capacitor connections. LED Outputs - Group A Signal POUT: Tie pins externally to PWR POUT Enable for Charge Pump and LEDs (current outputs). Logic input. High = LEDs ON. Low = LEDs OFF. Pulsing this pin with a PWM...