LM27953 Datasheet, PDF (1/11 Pages) National Semiconductor (TI) – White LED Driver with Four LED Current Sinks and 3/2x Switched Capacitor Boost

November 2004
LM27953
White LED Driver with Four LED Current Sinks and 3/2x
Switched Capacitor Boost
General 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. Regu-
lated 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 accommodate common-anode-type LEDs. The cur-
rent 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 high-
efficiency 3/2x-gain charge pump.
The LM27953 is available in National’s chip-scale 18-bump
micro SMD package.
Features
n Drives 4 Individual Common-Anode LEDs with up to
20mA 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 - 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 DS201280
20128001
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