LP5520 datasheet(9/46 Pages) TI1

9 / 46 page

CALIBRATION

EEPROM

SPI/I2C

INTER-

FACE

AND

CONTROL

BOOST

ADC

COLOR

PWM

LOGIC

LED

DRIVERS

CURRENT

DACS

ANALOG

SUPPORT

TEMP

SENSOR

LM20

MCU or

TESTER

with SPI

interface

COUT

CVDDD

CVDDA

100 nF

4.7 PF

CIN

2.9 V± 5.5V

5 V ± 20V

100 nF

2 x

4.7 PF

4.7 PH

ROUT

S1_IN

S2_IN

PWMR

PWMG

PWMB

VDDIO

RST

SS/SDA

SCK/SCL

SI/A0

IFSEL

GND_A

GND_LED

GND_SW

CVDDIO

100 nF

VDDD

VDDA

CVLDO 1 PF

LP5520

VLDO

0 ± 60 mA

BRC

Optional EMI

filter

close to SW pin

Optional

Ferrite

Bead

GND_T

CSW

RSW

3.9 :

330 pF

Optional HF

capacitor

CHF

68 pF

GOUT

BOUT

LSW

LP5520

www.ti.com

SNVS440B – MAY 2007 – REVISED MARCH 2016

Product Folder Links: LP5520

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7 Detailed Description

7.1 Overview

The LP5520 is an RGB backlight LED driver for small format color LCDs. The LP5520 offers a small and simple

driver solution without need for optical feedback. Calibration in display module production can be done in one

temperature. The LP5520 produces true white light over a wide temperature range.

Three independent LED drivers have accurate programmable current sinks with up to 60 mA current capability

and PWM modulation control. Using internal calibration memory and external temperature sensor, the RGB LED

currents are adjusted for perfect white balance independent of the brightness setting or temperature. The user

programmable calibration memory has intensity vs temperature data for each color. This white balance

calibration data can be programmed to the memory on the production line of a backlight module.

The LP5520 has a magnetic boost converter that creates supply voltage up to 20-V LED from the battery

voltage. The output can be set at 1-V step from 5 V to 20 V. In adaptive mode the circuit automatically adjusts

the output voltage to minimum sufficient level for lowest power consumption.

Temperature is measured using an external temperature sensor placed close to the LEDs. The second ADC

input can be used, for example, for ambient light measurement.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Start-Up Powering

VDDD and VDDA must be tied together and turned on first. VDDIO must be turned on at the same time as VDDD or

later. In the power-off sequence VDDIO must be turned off before VDDD or at the same time.

LP5520 Datasheet(PDF) 9 Page - Texas Instruments

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