LM2796 Datasheet, PDF (1/8 Pages) National Semiconductor (TI) – Dual-Display White LED Driver with 3/2x Switched Capacitor Boost

February 2004
LM2796
Dual-Display White LED Driver with 3/2x Switched
Capacitor Boost
General 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 20mA 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 pulse-
width 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 high-
efficiency 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 20mA 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 - 1kHz
n 18-bump Thin Micro SMD Package:
(2.1mm x 2.4mm x 0.6mm)
Applications
n Mobile Phone Display Lighting
n Mobile Phone Keypad Lighting
n PDAs
n General LED Lighting
Typical Application Circuit
© 2004 National Semiconductor Corporation DS200938
20093801
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