Texas Instruments LP5520 Datasheet

LP55XX

CALIBRATION

MEMORY

SPI/I2C INTER-

FACE

BOOSTADC

COLOR AND

BRIGHTNESS

PWM LOGIC

LED

DRIVERS

MCU WITH

I2C OR SPI

OUT

VDDA

VDDD

100 nF 4.7 PF

2.9 ± 5.5V 5 ± 20V

100 nF

2 x

4.7 PF

4.7 PH

ROUT

LP5520

DDA

DDD

S1_IN S2_IN

PWMR PWMG PWMB

LDO

NRST SS/SDA SCK/SCL

SI/A0 SO IFSEL

VDDIO

100 nF

DDIO

VLDO

1 PF

BRC

GND

LM 20

LDO

GOUT BOUT

Product Folder

Sample & Buy

Technical Documents

Tools & Software

Support & Community

SNVS440B –MAY 2007–REVISED MARCH 2016

LP5520 RGB Backlight LED Driver

LP5520

1 Features

• Temperature Compensated LED Intensity and Color

• Individual Calibration Coefficients for Each Color

• Color Accuracy ΔX and ΔY ≤ 0.003

• 12-Bit ADC for Measurement of 2 Sensors

• Adjustable Current Outputs for Red, Green, and Blue (RGB) LED

• 0.2% Typical LED Output Current Matching

• PWM Control Inputs for Each Color

• SPI™ and I2C-Compatible Interface

• Stand-Alone Mode With One-Wire Control

• Sequential Mode for One Color at a Time

• Magnetic High Efficiency Boost Converter

• Programmable Output Voltage from 5 V to 20 V

• Adaptive Output Voltage Control Option

• < 2-µA Typical Shutdown Current

2 Applications

• Color LCD Display Backlighting

• LED Lighting Applications

3 Description

The LP5520 is an RGB backlight LED driver for small format color LCDs. RGB backlights enable better colors on the display and power savings compared with white LED backlights. The device 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 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 device has a magnetic boost converter that creates a supply voltage of up to 20 V LED from the battery voltage. The output can be set at 1-V steps 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.

An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA.

PART NUMBER PACKAGE BODY SIZE (MAX)

LP5520 DSBGA (25) 2.787 mm × 2.621 mm (1) For all available packages, see the orderable addendum at

the end of the data sheet.

Typical Application

Device Information

(1)

LP5520

SNVS440B –MAY 2007–REVISED MARCH 2016

www.ti.com

1 Features.................................................................. 1

2 Applications ........................................................... 1

3 Description ............................................................. 1

4 Revision History..................................................... 2

5 Pin Configuration and Function........................... 3

6 Specifications......................................................... 4

6.1 Absolute Maximum Ratings ...................................... 4

6.2 ESD Ratings.............................................................. 4

6.3 Recommended Operating Conditions....................... 4

6.4 Thermal Information.................................................. 4

6.5 Electrical Characteristics........................................... 5

6.6 RGB Driver Electrical Characteristics (ROUT, GOUT,

BOUT Outputs) .......................................................... 5

6.7 Logic Interface Characteristics.................................. 6

6.8 Magnetic Boost DC-DC Converter Electrical

Characteristics ........................................................... 6

6.9 I2C Timing Parameters ............................................. 7

6.10 SPI Timing Requirements ....................................... 7

6.11 Typical Characteristics............................................ 8

7 Detailed Description.............................................. 9

7.1 Overview ................................................................... 9

7.2 Functional Block Diagram......................................... 9

7.3 Feature Description................................................... 9

7.4 Device Functional Modes........................................ 18

7.5 Programming........................................................... 22

7.6 Register Maps......................................................... 28

8 Application and Implementation ........................ 33

8.1 Application Information............................................ 33

8.2 Typical Applications ............................................... 33

9 Power Supply Recommendations...................... 37

10 Layout................................................................... 37

10.1 Layout Guidelines ................................................. 37

10.2 Layout Example .................................................... 38

11 Device and Documentation Support ................. 39

11.1 Device Support...................................................... 39

11.2 Documentation Support ........................................ 39

11.3 Community Resources.......................................... 39

11.4 Trademarks........................................................... 39

11.5 Electrostatic Discharge Caution............................ 39

11.6 Glossary................................................................ 39

12 Mechanical, Packaging, and Orderable

Information........................................................... 40

4 Revision History

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision A (May 2013) to Revision B Page

• Changed "R, G and B" to "Red, Green, and Blue"................................................................................................................. 1

• Deleted "Non-Linear Temperature Compensation" and "Ambient Light Compensation" from Applications ......................... 1

• Added Device Information and Pin Configuration and Functions sections, ESD Ratings and Thermal Information tables, Feature Description, Device Functional Modes, Application and Implementation, Power Supply

Recommendations, Layout, Device and Documentation Support, and Mechanical, Packaging, and Orderable

Information sections................................................................................................................................................................ 1

• Changed "MAIN, SUB" to " ROUT, GOUT, BOUT"................................................................................................................ 4

• Changed "come" to "are loaded".......................................................................................................................................... 12

• Changed ", and also the variable" to ". The variable parameter"......................................................................................... 18

• Changed "makes possible" to "allows" ................................................................................................................................. 19

• Changed "read" to "loaded".................................................................................................................................................. 19

• Changed "The stand-alone mode must be inhibited in automatic and manual modes by writing the control bit

<brc_off> high and by keeping BRC input low." to new text .............................................................................................. 19

Changes from Original (April 2013) to Revision A Page

• Changed layout of National Data Sheet to TI format ........................................................................................................... 32

Product Folder Links: LP5520

GNDT

SW FB

GND

_SW

GOUT BOUT

ROUT S2_IN

GND

_LED

S1_IN

BRC

VDDA

VDDD SO

SS/

SDA

GNDA

PWMR IFSEL

PWMG VDDIO

VLDO

NRST

PWMB

SI/ A0

SCK/

SCL

GNDT

SWFB

GND _SW

GOUTBOUT

ROUTS2_IN

GND

_LED

S1_IN

BRC

VDDA

VDDD

SI/ A0

SCK/

SCL

GNDA

PWMRIFSEL

PWMGVDDIO

VLDO

NRST

PWMB

SS/

SDA

www.ti.com

5 Pin Configuration and Function

LP5520

SNVS440B –MAY 2007–REVISED MARCH 2016

YZR Packge

25-Pin DSBGA

Top View

YZR Packge

25-Pin DSBGA

Bottom View

Pin Functions

NUMBER NAME

1A VDDA Power Supply voltage for analog circuitry 1B GNDT Ground Ground/Test 1C S1_IN Input ADC input 1, input for temperature sensor 1D BOUT Output Blue LED output 1E GOUT Output Green LED output 2A VLDO Power Internal LDO output 2B BRC Logic Input Brightness control for all LED outputs 2C S2_IN Input ADC input 2, input for optional second sensor 2D PWMB Logic Input PWM control for output B 2E ROUT Output Red LED output 3A VDDIO Power Supply voltage for input/output buffers and drivers 3B NRST Logic Input Master reset, active low 3C PWMG Logic Input PWM control for output G 3D GNDA Ground Ground for analog circuitry 3E GND_LED Ground Ground for LED currents 4A SS/SDA Logic Input/Output Slave select (SPI), serial data in/out (I2C) 4B SCK/SCL Logic Input Clock (SPI/I2C) 4C IFSEL Logic Input Interface selection (SPI or I2C-compatible, IF_SEL = 1 for SPI) 4D PWMR Logic Input PWM control for output R 4E GND_SW Ground Power switch ground 5A SO Logic Output Serial data out (SPI) 5B SI/A0 Logic Input Serial input (SPI), address select (I2C) 5C VDDD Power Supply voltage for digital circuitry 5D FB Input Boost converter feedback 5E SW Output Boost converter power switch

TYPE DESCRIPTION

Product Folder Links: LP5520

LP5520

SNVS440B –MAY 2007–REVISED MARCH 2016

www.ti.com

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)

V (SW, FB, ROUT, GOUT, BOUT) –0.3 22 V V

, V

DDA

DDD

DDIO

, V

LDO

Voltage on logic pins –0.3 V to V Continuous power dissipation

Junction temperature, T Storage temperature, T

(4)

J-MAX

stg

(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings

only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended

Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) All voltages are with respect to the potential at the GND pins. (3) If Military/Aerospace specified devices are required, contact the TI Sales Office/Distributors for availability and specifications. (4) Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ= 160°C (typical) and

disengages at TJ= 140°C (typical).

6.2 ESD Ratings

(ESD)

Electrostatic discharge

(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. (2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 Charged-device model (CDM), per JEDEC specification JESD22-C101

(1)(2)(3)

MIN MAX UNIT

–0.3 6 V

DDIO

0.3 V with 6 V maximum

Internally limited

125 °C

–65 150 °C

VALUE UNIT

(1)

(2)

±2000

±200

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)

V (SW, FB, ROUT, GOUT, BOUT) 0 21 V V

DDA,DDD

DDIO

Recommended load current (ROUT, GOUT, BOUT) per driver 0 60 mA Junction temperature, T Ambient temperature, T

(1) All voltages are with respect to the potential at the GND pins. (2) In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may

have to be derated. Maximum ambient temperature (T 125°C), the maximum power dissipation of the device in the application (P part/package in the application (R

(2)

) is dependent on the maximum operating junction temperature (T

A-MAX

), as given by the following equation: T

θJA

(1)

MIN MAX UNIT

2.9 5.5 V

1.65 V

DDA

–30 125 °C –30 85 °C

), and the junction-to ambient thermal resistance of the

D-MAX

A-MAX

= T

J-MAX-OP

– (R

θJA

× P

D-MAX

J-MAX-OP

6.4 Thermal Information

LP5520

THERMAL METRIC

θJA

θJC(top)

θJB

Junction-to-ambient thermal resistance 58.2 °C/W Junction-to-case (top) thermal resistance 0.3 °C/W Junction-to-board thermal resistance 7.9 °C/W Junction-to-top characterization parameter 0.5 °C/W Junction-to-board characterization parameter 7.9 °C/W

(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application

report, SPRA953.

(1)

UNITYZR (DSBGA)

25 PINS

Product Folder Links: LP5520

LP5520

www.ti.com

SNVS440B –MAY 2007–REVISED MARCH 2016

6.5 Electrical Characteristics

Unless otherwise noted typical limits are for TJ= 25°C, minimum and maximum limits apply over the operating ambient temperature range (–30°C < TJ< +85°C), and specifications apply to the LP5520 Functional Block Diagram with: C 100 nF, C

= 2 × 4.7 µF, 25 V, CIN= 10 µF, 6.3 V, L1 = 4.7 µH.

OUT

(1)(2)(3)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

VDD

VDDIO

LDO

Standby supply current (V

+ V

DDD

)

DDA

No-boost supply current (V

+ V

DDD

)

DDA

No-load supply current (V

+ V

)

DDD

standby supply current NSTBY = L 1 µA

DDA

DDIO

NSTBY = L, V NSTBY = L , V NSTBY = H,

EN_BOOST = L NSTBY = H, EN_BOOST = H

AUTOLOAD = L

Internal LDO output voltage VIN≥ 2.9 V, TJ= 25°C 2.77 2.80 2.84 V Internal LDO output current Current to external load 1 mA

≥ 1.65 V 1.7 7

DDIO

= 0 V 1

DDIO

0.9

1.4

(1) All voltages are with respect to the potential at the GND pins. (2) Minimum and maximum limits are specified by design, test or statistical analysis. Typical numbers represent the most likely norm. (3) Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics.

VDDA/D

6.6 RGB Driver Electrical Characteristics (ROUT, GOUT, BOUT Outputs)

Typical limits are for TJ= 25°C, minimum and maximum limits apply over the operating ambient temperature range (–30°C < TJ< +85°C); over operating free-air temperature range (unless otherwise noted).

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

LEAKAGE

MAX

MATCH

PWM

RGB

SAT

MAX

(1) Matching is the maximum difference from the average when all outputs are set to same current. (2) Saturation voltage is defined as the voltage when the LED current has dropped 10% from the value measured at 2 V.

ROUT, GOUT, BOUT pin leakage current

Maximum sink current

Current accuracy of ROUT, GOUT, and BOUT

Matching

(1)

Outputs ROUT, GOUT, BOUT control = 255 (FFH)

Output current set to 20 mA

Output current set to 60 mA

19 20 21 mA

–5% 5%

54 60 66 mA

–10% 10%

Between ROUT, GOUT, BOUT at 20 mA current ±0.2% ±2%

0.1 1 µA

PWM cycle time Accuracy proportional to internal clock frequency 820 µs

RGB switching frequency

Saturation voltage

(2)

External PWM maximum frequency

<pwm_fast> = 0 1.22 kHz <pwm_fast> = 1 19.52 I

= 60 mA 550 mV

(LED)

= 60 mA, TJ= 25°C 1 MHz

(LED)

µA

Product Folder Links: LP5520

LP5520

SNVS440B –MAY 2007–REVISED MARCH 2016

6.7 Logic Interface Characteristics

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

LOGIC INPUTS SS, SI/A0, SCK/SCL, IFSEL, NRST, PWMR, PWMG, PWMB and BRC

SCK/SLC

LOGIC INPUT NRST

NRST

LOGIC OUTPUT SO

LOGIC OUTPUT SDA

Input low level 0.2 × V Input high level 0.8 × V

DDIO

Logic input current −1 1 µA

I2C mode 0.4

Clock frequency

SPI mode, V SPI mode, 1.65 V < V

1.8 V

> 1.8 V 13

DDIO

Input low level 05 V Input high level 1.2 V Logic input current –1 1 µA Reset pulse width 10 µs

Output low level

Output high level

ISO= 3 mA V

> 1.8 V

DDIO

ISO= 2 mA

1.65 V < V ISO= –3 mA

> 1.8 V

DDIO

ISO= –2 mA

1.65 V < V

DDIO

< 1.8 V

DDIO

− 0.5 V

0.3 0.5 V

− 0.3 V

DDIO

− 0.3 V

DDIO

Output leakage current VSO= 2.8 V 1 µA

Output low level I

= 3 mA 0.3 0.5 V

SDA

www.ti.com

V V

MHz

6.8 Magnetic Boost DC-DC Converter Electrical Characteristics

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

LOAD

OUT

RDS

PWM

PULSE

STARTUP

MAX

Maximum continuous load current

Output voltage accuracy (FB pin)

Switch ON resistance ISW= 0.5 A 0.3 Ω

Frequency accuracy

Switch pulse minimum width no load 50 ns Start-up time 20 ms SW pin current limit 1100 mA

2.9V = VIN, V TJ= 25°C

2.9 ≤ VIN≤ 5.5 V, V TJ= 25°C

2.9 ≤ VIN≤ 5.5 V, V

OUT

= 20 V

OUT

= 20 V –5% 5%

OUT

–1.7% 1.7%

TJ= 25°C −6% ±3% 6%

–9% 9%

Product Folder Links: LP5520

SCK

Data

BIT 1 LSB IN

LSB OUTBIT 1

MSB OUT

BIT 7BIT 8BIT 9BIT 14MSB IN

R/WAddress

2 1

SDA

SCL

4 9

1 7

www.ti.com

SNVS440B –MAY 2007–REVISED MARCH 2016

6.9 I2C Timing Parameters

= 3 V to 4.5 V, V

DD1,2

= 1.8 V To V

DDIO

; see Figure 1.

DD1,2

MIN MAX UNIT

1 Hold time (repeated) START condition 0.6 µs 2 Clock low time 1.3 µs 3 Clock high time 600 ns 4 Setup time for a repeated START condition 600 ns 5 Data hold time (output direction, delay generated by LP5520) 300 900 ns 5 Data hold time (input direction, delay generated by Master) 0 900 ns 6 Data setup time 100 ns 7 Rise time of SDA and SCL 20 + 0.1C 8 Fall time of SDA and SCL 15 + 0.1C

b b

300 ns

300 ns 9 Setup time for STOP condition 600 ns 10 Bus free time between a STOP and a START condition 1.3 µs C

Capacitive load for each bus line 10 200 pF

6.10 SPI Timing Requirements

See Figure 2.

MIN MAX UNIT

1 Cycle time 70 ns 2 Enable lead time 35 ns 3 Enable lag time 35 ns 4 Clock low time 35 ns 5 Clock high time 35 ns 6 Data setup time 0 ns 7 Data hold time 25 ns 8 Data access time 30 ns 9 Disable time 20 ns 10 Data valid 40 ns 11 Data hold time 0 ns

LP5520

Figure 1. I2C Timing Diagram

Figure 2. SPI Timing Diagram

Product Folder Links: LP5520

AUTOLOAD OFF

AUTOLOAD ON

20.017.014.011.08.05.0

OUTPUT VOLTAGE (V)

INPUT CURRENT (mA)

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 TIME (s)

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0.0

BOOST

LOAD

DRIVER

VOLTAGE (V)

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0.0

0 60 120 180 240 300 360

OUTPUT CURRENT (mA)

20.0

18.0

16.0

14.0

12.0

10.0

8.0

6.0

4.0

VIN= 2.9V

VIN= 3.6V

INDUCTOR TDK VLF3010 - 4.7 mH

OUTPUT VOLTAGE (V)

OUT

= 20V

OUT

=1 5V

OUT

= 10V

INDUCTOR TDK VLF3010 - 4.7 PH

LOAD

= 60 mA

600 600 500 450 400 350 300 250 200 150

BATTERY CURRENT (mA)

BATTERY VOLTAGE (V)

2.9 3.1 3.3 3.5 3.7 3.9 4.1

OUTPUT CURRENT (mA)

OUTPUT VOLTAGE (V)

0.0 0.2 0.4 0.6 0.8 1.0

0.0

10.0

20.0

30.0

40.0

50.0

60.0

OUTPUT CURRENT (mA)

OUTPUT VOLTAGE (V)

0.0 0.2 0.4 0.6 0.8 1.0

0.0

10.0

20.0

30.0

40.0

50.0

60.0

LP5520

SNVS440B –MAY 2007–REVISED MARCH 2016

6.11 Typical Characteristics

6.11.1 RGB Driver Typical Characteristics

www.ti.com

Figure 3. V

SAT

vs I

LED

6.11.2 Boost Converter Typical Characteristics

VIN= 3.6 V, V

Figure 5. Boost Maximum Output Voltage vs Current

= 15 V, if not otherwise stated.

OUT

Figure 4. V

SAT

vs I

LED

Figure 6. Battery Current vs Voltage

Figure 7. Auto-Load Effect on Input Current, No Load Figure 8. Adaptive Output Voltage Operation

Product Folder Links: LP5520

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

OUT

VDDD

VDDA

100 nF

4.7 PF

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

DDIO

RST

SS/SDA

SCK/SCL

SI/A0

IFSEL

GND_A GND_LED GND_SW

VDDIO

100 nF

DDD

DDA

VLDO

1 PF

LP5520

LDO

0 ± 60 mA 0 ± 60 mA

0 ± 60 mA

BRC

Optional EMI

filter

close to SW pin

Optional

Ferrite

Bead

GND_T

3.9 :

330 pF

Optional HF

capacitor

68 pF

GOUT BOUT

LP5520

www.ti.com

SNVS440B –MAY 2007–REVISED MARCH 2016

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

and V

must be tied together and turned on first. V

DDA

7.3 Feature Description

7.3.1 Start-Up Powering

DDD

later. In the power-off sequence V

must be turned off before V

DDIO

must be turned on at the same time as V

DDD

Product Folder Links: LP5520

or at the same time.

DDD

-40 -20 0 20 40 60 80 TEMPERATURE

4000 3500 3000 2500 2000 1500 1000

500

Red

Blue

Green

INTENSITY

4000 3500

2500 2000

3000

1500 1000

500

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

700

620

600

580

560

540

520

500

480

470

Target for white light

Green

Blue

Red

460

490

380

0 0.1 0.3 0.4 0.5 0.6 0.7 0.80.2

DDIO

Power ON Power OFF

DDD

and V

DDA

LP5520

SNVS440B –MAY 2007–REVISED MARCH 2016

www.ti.com

Feature Description (continued)

Figure 9. Power-On Signal Timing

7.3.2 RGB Driver Functionality

7.3.2.1 White Balance Control

The LP5520 is designed to provide spectrally rich white light using a three-color RGB LED. White light is obtained when the red, green, and blue LED intensities are in proper balance. The LED intensities change independently with temperature. For maintaining the purity of the white color and the targeted total intensity, precise temperature dependent intensity control for each LED is required. The color coordinates in this document refer to the CIE 1931 color graph (x,y system).

Figure 11 shows a typical RGB LED intensity behavior on a 12-bit scale (0 to 4095) at constant 20-mA LED

currents. Figure 12 shows the typical color coordinate change for an uncompensated RGB LED. Figure 13 shows the corresponding PWM values for achieving constant intensity white light across the temperature range. The PWM values have been saturated at 104°C to avoid overheating the LED and to better utilize the PWM range. The white balance is not maintained above 104°C in this case.

Figure 10. CIE 1931 Color Graph

Figure 11. LED Intensity vs Temperature

Product Folder Links: LP5520

-40 -20 0 20 40 60 80 TEMPERATURE, °C

0.310

0.305

0.300

0.295

0.290

COLOR COORDINATES

0.310

0.305

0.300

0.295

0.290

-40 -20 0 20 40 60 80 100 120 TEMPERATURE

4000 3500 3000 2500 2000 1500 1000

500

Red

Blue

Green

PWM VALUE

4000 3500

3000

2500 2000 1500 1000

500

-40 -14 12 38 64 90

TEMPERATURE,°C

0.34

0.32

0.31

0.29

0.28

0.26

COLOR COORDINATE

0.34

0.32

0.31

0.29

0.28

0.26

LP5520

www.ti.com

SNVS440B –MAY 2007–REVISED MARCH 2016

Feature Description (continued)

Figure 12. Typical Color Coordinates vs Temperature for Uncompensated RGB LED

The compensation values for the measured temperatures can be easily calculated when the intensity vs temperature information is available. For the best accuracy the iterative calibration approach must be used.

The compensation values must be converted to 16°C intervals when they are programmed to the calibration EEPROM. The evaluation software has import function, which can be used to convert the measured compensation data to the 16°C interval format. The measured data can have any temperature points, and the software fits a curve through the measured points and calculate new PWM values in fixed temperatures using the curves.

Typical color coordinate and intensity stability over temperature are shown in Figure 14 and Figure 15.

Figure 13. Compensation PWM Values

Figure 14. Compensated Color Coordinates vs Temperature

Product Folder Links: LP5520

-40 -20 0 20 40 60 80 TEMPERATURE, °C

1500

1450

1400

1350

1300

INTENSITY BLUE

1500

1450

1400

1350

1300

LP5520

SNVS440B –MAY 2007–REVISED MARCH 2016

www.ti.com

Feature Description (continued)

Figure 15. Compensated Blue LED Intensity vs Temperature

7.3.2.2 LED Brightness Control

The LED brightness is defined by two factors, the current through the LED and the PWM duty cycle. The constant current outputs ROUT, GOUT, and BOUT can be independently set to sink between 0 and 60 mA. The 8-bit current control has 255 levels, and the step size is 235 µA. In manual mode the current is defined with the current control (R/G/B) registers (01H, 02H, and 03H). In automatic mode the current settings are loaded from the EEPROM.

The PWM control has 12-bit resolution, which means 4095 steps. The minimum pulse width is 200 ns, and the frequency can be set to either 1.2 kHz or 19.2 kHz. The duty cycle range is from 0 to 100% (0 to 4095). The output PWM value is obtained by multiplication of three factors. The first factor is the temperature-based value from the EEPROM. The second factor is the correction register setting, which is independent for each color. The third factor is the brightness register setting, which is common to all colors.

The temperature-based PWM values are stored in the EEPROM at 16°C intervals starting from –40°C and ending to 120°C. PWM values for the temperatures between the stored points are interpolated.

LED brightness has 3-bit logarithmic control. The control bits are in the pwm_brightness (04H) register. The 3-bit value defines a multiplier for the 12-bit PWM value obtained from the memory according to Table 1.

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SELF

HEATING

COMPENS.

EEPROM

LOGIC

ADC

LOGIC

BRIGHTNESS

0.8 ± 100%

8 STEP LOG

CORRECTION R

0 ± 200%

(AGEING COMP)

CURRENT R

0 ± 60mA

TEMP

SENSOR

PWM

GEN

S1_IN

PWM_R

12 1212

5 MHz

ROUT

LP5520

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SNVS440B –MAY 2007–REVISED MARCH 2016

Feature Description (continued)

Table 1. PWM Value Multipliers

CONTROL BYTE <bri[2:0]>

0 0.008 0.8 1 0.016 1.6 2 0.031 3.1 3 0.063 6.3 4 0.125 12.5 5 0.250 25 6 0.500 50 7 1.000 100

(1) PWM Brightness register control

The brightness correction can be used for aging compensation or other fine-tuning. There is an 8-bit correction register for each output. The PWM value obtained from the memory is multiplied by the correction value. The default correction value is 1. Correction range is from 0 to 2 and the LSB is 0.78% (1/128).

(1)

MULTIPLIER INTENSITY ( %)

Shown complete only for red channel

Figure 16. LED Control Principle

7.3.2.3 LED PWM Control

The PWM frequency can be selected of two alternatives, slow and fast, with the control bit <pwm_fast>. The slow frequency is 1.2 kHz. In the fast mode the PWM frequency is multiplied by 16, and the frequency is 19.2 kHz. Fast mode is the default mode after reset. The single pulse in normal PWM is split in 16 narrow pulses in fast PWM. Higher frequency helps eliminate possible noise from the ceramic capacitors and it also reduces the ripple in the boost voltage. Minimum pulse length is 200 ns in both modes.

The PWM pulses of each output do not start simultaneously in order to avoid high current spike. Red starts in the beginning of the PWM cycle, Green is symmetric with the cycle center and Blue ends in the end of the cycle. For PWM values less than 33% for each output, the output currents are completely non-overlapping. With higher PWM values the overlapping increases.

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ROUT

GOUT

BOUT

PWMR

PWMG

PWMB

10 ms/100 Hz

3.333 ms

Dead time

Internal PWM cycle

1 2 3

1 2

ROUT

GOUT

BOUT

50%

100%

819 Ps/1.22 kHz in normal PWM

52 Ps/19.2 kHz in fast PWM

LP5520

SNVS440B –MAY 2007–REVISED MARCH 2016

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Figure 17. Pulse Positions in the PWM Cycle

7.3.2.4 Sequential Mode

Completely non-overlapping timing can be obtained by using the sequential mode as shown in Figure 18. The timing is defined with external PWM control inputs. The minimum trigger pulse width in the PWM inputs is 1 µs. There is no limitation on the maximum width of the pulse as long as it is shorter than the whole sequence.

Figure 18. Non-Overlapping External Synchronized Sequential Mode

In sequential mode the PWM cycle is synchronized to trigger pulses and the amount of PWM pulses per trigger can be defined to 2, 3 or 4 using the <seq_mode0> and <seq_mode1> control bits. This makes possible to use sequence lengths of about 5 ms, 7.5 ms or 10 ms. Fast PWM can be used in sequential mode, but the frame timing is as with normal PWM.

The PWM timing and synchronization timing originate from different clock sources. Some margin must be allowed for clock tolerances. This margin shows as a dead time in the waveform graph. Some dead time must be allowed so that no PWM pulse is clipped. Clipping would distort the intensity balance between the LEDs. The dead time causes some intensity reduction, but assures the current balance.

PWM mode is defined by <seq_mode1> and <seq_mode2> control bits of rgb_control (00H) register:

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+ 32 hidden pages

Texas Instruments LP5520 Datasheet

1 Features

2 Applications

3 Description

Table of Contents

4 Revision History

5 Pin Configuration and Function

6 Specifications

6.1 Absolute Maximum Ratings

6.2 ESD Ratings

6.3 Recommended Operating Conditions

6.4 Thermal Information

6.5 Electrical Characteristics

6.6 RGB Driver Electrical Characteristics (ROUT, GOUT, BOUT Outputs)

6.7 Logic Interface Characteristics

6.8 Magnetic Boost DC-DC Converter Electrical Characteristics

6.9 I2C Timing Parameters

6.10 SPI Timing Requirements

6.11 Typical Characteristics

6.11.1 RGB Driver Typical Characteristics

6.11.2 Boost Converter Typical Characteristics

7 Detailed Description

7.1 Overview

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Start-Up Powering

7.3.2 RGB Driver Functionality

7.3.2.1 White Balance Control

7.3.2.2 LED Brightness Control

7.3.2.3 LED PWM Control

7.3.2.4 Sequential Mode