LM2796TLEV National Semiconductor, LM2796TLEV Datasheet

BOARD EVALUATION LM2796TL

LM2796TLEV

Manufacturer Part Number
LM2796TLEV
Description
BOARD EVALUATION LM2796TL
Manufacturer
National Semiconductor
Series
PowerWise®r
Datasheets

Specifications of LM2796TLEV

Current - Output / Channel
20mA
Outputs And Type
7, Non-Isolated
Voltage - Output
4 V
Features
Charge Pump
Voltage - Input
2.7 ~ 5.5V
Utilized Ic / Part
LM2796
Lead Free Status / RoHS Status
Not applicable / Not applicable
© 2004 National Semiconductor Corporation
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.
Typical Application Circuit
DS200938
Features
n Drives up to 7 LEDs with up to 20mA each
n LEDs controlled in 2 Distinct Groups, for Backlighting 2
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:
Applications
n Mobile Phone Display Lighting
n Mobile Phone Keypad Lighting
n PDAs
n General LED Lighting
Displays (main LCD and sub-LCD)
(2.1mm x 2.4mm x 0.6mm)
20093801
February 2004
www.national.com

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LM2796TLEV Summary of contents

Page 1

... The LM2796 is available in National’s chip-scale 18-bump micro SMD package. Typical Application Circuit © 2004 National Semiconductor Corporation Features n Drives LEDs with up to 20mA each n LEDs controlled in 2 Distinct Groups, for Backlighting 2 Displays (main LCD and sub-LCD) ...

Page 2

Connection Diagram Pin Description Pin #s Pin Names GND A3 P OUT A1, B2, A5, E1 C1+, C1-, C2+, C2 D6, E5, D4, E3 D1A, D2A, D3A, D4A C5, B4, C3 D1B, D2B, D3B ...

Page 3

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. V pin voltage IN EN, ENA, ENB pin voltages Continuous Power Dissipation (Note 3) Junction Temperature (T ) J-MAX Storage Temperature Range Maximum Lead Temperature (Soldering, 10 sec.) ...

Page 4

Electrical Characteristics Limits in standard typeface and typical values apply for T temperature range (-30˚C ≤ T ≤ +85˚C) . Unless otherwise specified Group B LEDs not ON simultaneously (ENA = and C = 1µF. ...

Page 5

Typical Performance Characteristics 2.0V; V(ENA) = 2.0V; V(ENB) = 0V; R SET LED Current vs. Input Voltage LED Current vs. PWM Duty Cycle, PWM Applied to ENA and/or ENB Unless otherwise specified 8.3 kΩ ...

Page 6

Circuit Description OVERVIEW The LM2796 is primarily intended for Lithium-Ion battery driven white-LED drive applications, and is well suited to drive white LEDs that are used for backlighting small-format displays. The part has seven matched constant-current out- puts, each capable ...

Page 7

Circuit Description (Continued) LED outputs rise at the rate of the reference voltage ramp. Due to the soft-start circuitry, turn-on time of the LM2796 is approximately 100µs (typ.). Thermal Protection Internal thermal protection circuitry disables the LM2796 when the junction ...

Page 8

... BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. ...

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