LP5520 datasheet(36/46 Pages) TI1

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CALIBRATION

EEPROM

SPI / I2C

INTER-

FACE

AND

CONTROL

BOOST

ADC

COLOR

PWM

LOGIC

LED

DRIVERS

CURRENT

DACS

ANALOG

SUPPORT

TEMP

SENSOR

LM20

COUT

CVDDA

CVDDD

100 nF

4.7 PF

CIN

2.9 ± 5.5V

5 ± 20V

100 nF

10 PF

4.7 PH

S1_IN

S2_IN

PWMR

PWMG

PWMB

VDDIO

NRST

SS/SDA

SCK/SCL

SI/A0

IFSEL

GND_A

GND_LED

GND_SW

VDDD

VDDA

CVLDO

1 PF

LP5520

VLDO

20 mA

BRC

GND_T

ROUT

GOUT

BOUT

PWM INPUT

ON/OFF/

BRIGHTNESS

20 mA

CVDDIO

100 nF

ADAPTIVE

LP5520

SNVS440B – MAY 2007 – REVISED MARCH 2016

www.ti.com

Product Folder Links: LP5520

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8.2.2 Stand-Alone Typical Application

In stand-alone mode the operation is controlled through a single PWM brightness input, BRC. After power-up or

reset the LP5520 is ready for stand-alone operation without any setup through the serial interface. The stand-

alone mode is entered with a rising edge in the BRC input. The boost converter operates in adaptive mode. The

LED current settings are read from EEPROM. The LED brightness is controlled with a PWM signal in the BRC

input. The BRC PWM frequency must be between 2 and 10 kHz.

Figure 35. Typical Stand-Alone Application

8.2.2.1 Design Requirements

For typical RGB backlight LED-driver stand-alone applications, use the parameters listed in Table 14.

Table 15. Design Parameters

DESIGN PARAMETER

EXAMPLE VALUE

Input voltage range

2.9 V to 5.5 V

Maximum output voltage

20 V

LED configuration

3 strings with 6 LEDs in series

LED current

Maximum 60 mA per string

Brightness control

With BRC input, 2-kHz PWM signal; 8 steps

Operation mode

Stand-alone operation

Input capacitor

10 µF, 6.3 V

Output capacitors

2 × 4.7 µF, 25 V

Inductor

4.7 µH

Temperature sensor

LM20

8.2.2.2 Detailed Design Procedure

See Detailed Design Procedure.

8.2.2.3 Application Curves

See Application Curves.

LP5520 Datenblatt(PDF) 36 Page - Texas Instruments

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