LM2755

1 PF

1 PF

SDIO

GND

0.47 PF

0.47 PF

SCL

D1

VIO

D2

D3

12.5 k:

ADDR

SYNC

C1+

C2+

C1-

C2-

HWEN

Capacitors:

TDK C1005X5R1A105M and C1005X5R1A474M ,

or 1 PF and 0.47 PF single capacitor equivalent

C1

Dx Pins

SYNC

SDIO

SCL

VIO

ADR

C2

HWEN

3.1 mm

LM2755

www.ti.com

SNVS433D – OCTOBER 2007 – REVISED APRIL 2013

Check for Samples: LM2755

1

FEATURES

DESCRIPTION

The LM2755 is a charge-pump-based, constant

2

•

90% Peak Efficiency

current LED driver capable of driving 3 LEDs with a

•

total output current up to 90mA. The diode current

•

No Inductor Required: Only 4 Inexpensive

waveforms of each LED can be trapezoidal with

Ceramic Caps

timing and level parameters (rise time, fall time, high

level,

low

level,

delay,

high

time,

low

time)

•

3 Independently Controlled Constant Current

Outputs

brightness

levels

found

on

the

LM2755

are

•

Programmable Trapezoidal Dimming

exponentially spaced (as opposed to linearly spaced)

Waveform on Each Output

to better match the response of the human eye to

changing brightness levels.

•

Programmable Timing Control Via Internal

Registers and External Clock Synchronization

The device requires only four small and low-cost

Input

ceramic capacitors. The LM2755 provides excellent

efficiency without the use of an inductor by operating

•

32 Exponential Dimming Steps with 800:1

the charge pump in a gain of 3/2 or in a gain of 1.

Dimming Ratio

Maximum efficiency is achieved over the input

•

voltage range by actively selecting the proper gain

Compatible Interface

based on the LED forward voltage requirements.

•

Hardware Enable Pin

The pre-regulation scheme used by the LM2755 is

•

Wide Input Voltage Range: 2.7V to 5.5V

optimized to ensure low conducted noise on the

•

Tiny 18-bump Thin DSBGA : 1.8mm x 1.6mm x

input. An internal soft-start circuitry eliminates high

0.6mm

inrush current at start-up. The LM2755 consumes

3µA (typ.) of supply current in shut-down.

APPLICATIONS

The LM2755 is available in Texas Instruments' tiny

18-bump thin DSBGA package.

•

Indicator LEDs

•

Keypad LED Backlight

•

Display LED Backlight

•

Fun-light LEDs

TYPICAL APPLICATION CIRCUIT

Figure 1. Typical Application Circuit

Figure 2. Minimum Solution Size

1

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2

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PRODUCTION DATA information is current as of publication date.

Copyright © 2007–2013, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.