LM2796_16 Datasheet, PDF (1/16 Pages) Texas Instruments – LM2796 Dual-Display White LED Driver with 3/2x Switched Capacitor Boost

LM2796
www.ti.com
SNVS273A – MAY 2004 – REVISED MAY 2013
LM2796 Dual-Display White LED Driver with 3/2x Switched Capacitor Boost
Check for Samples: LM2796
FEATURES
1
•2 Drives up to 7 LEDs with up to 20mA Each
• LEDs Controlled in 2 Distinct Groups, for
Backlighting 2 Displays (Main LCD and Sub-
LCD)
• Excellent Current and Brightness Matching
• High-Efficiency 3/2x Charge Pump
• Extended Li-Ion Input: 2.7V to 5.5V
• PWM Brightness Control: 100Hz - 1kHz
• 18-bump Thin DSBGA Package: (2.1mm x
2.4mm x 0.6mm)
APPLICATIONS
• Mobile Phone Display Lighting
• Mobile Phone Keypad Lighting
• PDAs
• General LED Lighting
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 3/2×-gain charge
pump.
The LM2796 is available in TI’s chip-scale 18-bump
DSBGA package.
Typical Application Circuit
C1
1 PF
C2
1 PF
Master Enable and Current Source Enables for
ON/OFF Control and PWM Dimming
VIN
2.7V to 5.5V
CIN
1 PF*
C1+
C1- C2+
C2-
VIN
3/2× Charge Pump
(1× when VIN > 4.7V)
GND
D1A D2A D3A D4A
EN
ENA
ENB
POUT
LM2796
D1B
D2B
ISET
D3B
CPOUT
1 PF*
RSET
Capacitors: TDK C1608X5R1A105K,
or equivalent
*If total LED current is above 80 mA, as can occur
when all 7 outputs are ON simultaneously, 2.2 PF
capacitors are recommended for CIN and CPOUT.
1
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2004–2013, Texas Instruments Incorporated