ANALOG DEVICES ADD5203 Service Manual

8-String, White LED Driver with SMBus and

FEATURES

White LED driver based on inductive boost converter

Integrated 50 V MOSFET with 2.9 A peak current limit Input voltage range: 6 V to 21 V Maximum output adjustable up to 45 V 350 kHz to 1 MHz adjustable operating frequency Overvoltage protection (OVP) up to typical 47.5 V Built-in soft start for boost converter

Drives up to eight LED current strings

LED current adjustable up to 30 mA for each channel Headroom control to maximize efficiency Adjustable dimming frequency: 200 Hz to 10 kHz LED open and short fault protection

Selectable dimming control interface methods

PWM input SMBus serial input

Selectable dimming modes

Fixed delay PWM dimming control with 8-bit resolution No delay PWM dimming control with 8-bit resolution Direct PWM dimming control DC current dimming control with 8-bit resolution

General

Thermal shutdown Undervoltage lockout 28-lead, 4 mm × 4 mm × 0.75 mm LFCSP_WQ

PWM Input for LCD Backlight Applications

ADD5203

FUNCTIONAL BLOCK DIAGRAM

STEP-UP SWITCHING REGULATOR

EIGHT CURRENT S OURCES

PWM DUTY EXTRACTOR

8-BIT BRIGHTNESS CONTROL LOGIC

FIXED DELAY/NO DELAY DIRECT PWM /

DC CURRENT DIMMING CONTROL

WITH PWM AND/OR SMBus INTERFACE

UNDERVOLTAGE LOCKOUT

INTERNAL SOF T START

THERMAL PROTECTI ON

OVERVOLTAGE PROTECTION

AUTODISABLE F OR LED OP EN/SHORT

08717-001

Figure 1.

APPLICATIONS

Notebook PCs, UMPCs, and monitor displays

GENERAL DESCRIPTION

The ADD5203 is a white LED driver for backlight applications based on high efficiency, current-mode, step-up converter technology. It is designed with a 0.15 , 2.9 A internal switch and a pin-adjustable operating frequency between 350 kHz and 1 MHz.

The ADD5203 contains eight regulated current sources for uniform brightness intensity. Each current source can be driven up to 30 mA, and the LED driving current is pin adjustable by an external resistor. The ADD5203 drives up to eight parallel strings of multiple series connected LEDs with a ±1.5% current matching between strings.

The ADD5203 provides various dimming modes. Each dimming mode is selectable with an external dimming mode selection pin. The LED dimming control interface can be achieved through PWM input and/or SMBus. The device

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

provides adjustable output dimming frequency range from 200 Hz to 10 kHz by an external resistor and capacitor. The ADD5203 operates over an input voltage range of 6 V to 21 V, but the device can function with a voltage as low as 5.6 V.

The ADD5203 also has multiple safety protection features to prevent damage during fault conditions. If any LED is open or short, the device automatically disables the faulty current source. The internal soft start prevents inrush current during startup. Thermal shutdown protection prevents thermal damage.

The ADD5203 is available in a low profile, thermally enhanced, 4 mm × 4 mm × 0.75 mm, 28-lead, RoHS-compliant lead frame chip scale package (LFCSP_WQ) and is specified over the industrial temperature range of −25°C to +85°C.

ADD5203

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

Applications ....................................................................................... 1

Functional Block Diagram .............................................................. 1

General Description ......................................................................... 1

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

Circuit Diagram ................................................................................ 3

Specifications ..................................................................................... 4

Step-Up Switching Regulator Specifications ............................. 4

LED Current Regulation Specifications .................................... 4

SMBus Specifications ................................................................... 5

General Specifications ................................................................. 6

Absolute Maximum Ratings ............................................................ 7

Thermal Resistance ...................................................................... 7

ESD Caution .................................................................................. 7

Pin Configuration and Function Descriptions ............................. 8

Typical Performance Characteristics ............................................. 9

Theory of Operation ...................................................................... 11

Current-Mode, Step-Up Switching Regulator Operation ..... 11

Internal 3.3 V Regulator ............................................................ 11

Boost Converter Switching Frequency .................................... 11

Dimming Frequency (f

Current Source ............................................................................ 11

Dimming Control Interface ...................................................... 11

PWM Dimming Mode .............................................................. 12

Safety Features ............................................................................ 12

SMBus Interface.......................................................................... 13

SMBus Register Description ..................................................... 15

External Component Selection Guide ..................................... 17

Layout Guidelines....................................................................... 18

Typical Application Circuits ......................................................... 20

Outline Dimensions ....................................................................... 23

Ordering Guide .......................................................................... 23

) ...................................................... 11

PWM

REVISION HISTORY

5/10—Revision 0: Initial Version

Rev. 0 | Page 2 of 24

ADD5203

CIRCUIT DIAGRAM

VIN VDDIO SHDN NC OVP

26 4 25 16 22

COMP

SET

FB1

UVP REF

REF

CURRENT

REFERENCE

LINEAR

REGULATOR

VOLTAGE

REFERENCE

UVP

COMP

ERROR

AMP

HEADROOM CONTROL

CURRENT SOURCE 1

REF

ADD5203

LIGHT LOAD

PWM

COMP

SHUTDOWN

DCOMP

TSD FAULT

LED OPEN/S HORT FAU LT D ET EC TO R

DREF

THERMAL

SHUTDOWN

OCP FAULT

OSC

∑

CURRENT SENSE

SOFT START

TSD FAULT

OCP FAULT

OCP REF

OVP REF

SENSE

FSLCT

PGND

FB2

FB3

FB4

FB5

FB6

FB7

CURRENT SOURCE 2

CURRENT SOURCE 3

CURRENT SOURCE 4

CURRENT SOURCE 5

CURRENT SOURCE 6

CURRENT SOURCE 7

CURRENT SOURCE 8FB8

AGND

ID REGISTER

FAU LT/STAT US

CURRENT SOURCE CONT ROLLER

DEVICE CONTRO L

BRIGHTNESS CONTROL

SMBus INTERFACE DUTY GENERATOR

PWMI DUTY

EXTRACTOR

OPERATION

MODE

SELECTION

PWM

OSCILLATOR

SDA

SCL

PWMI

SEL1

SEL2

C_FPWM

R_FPWM

08717-002

Figure 2. Circuit Diagram

Rev. 0 | Page 3 of 24

ADD5203

SPECIFICATIONS

STEP-UP SWITCHING REGULATOR SPECIFICATIONS

VIN = 12 V,

Table 1.

Parameter Symbol Test Conditions Min Typ Max Unit

SUPPLY

Input Voltage Range VIN 6 21 V

BOOST OUTPUT

Output Voltage V

SWITCH

On Resistance R Leakage Current I Peak Current Limit ICL Duty cycle (D) = D

OSCILLATOR

Switching Frequency fSW R f Maximum Duty Cycle D

SOFT START

Soft Start Time tSS 1.5 ms

OVERVOLTAGE PROTECTION

Overvoltage Rising Threshold on OVP Pin V Overvoltage Falling Threshold on OVP Pin V

SHDN

= high, TA = −25°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.

45 V

OUT

DS(ON)

44 70 μA

LKG

MAX

1.154 1.20 1.267 V

OVPR

1.050 1.12 1.188 V

OVPF

VIN = 12 V, ISW = 100 mA 150 210 mΩ

2.9 A

MAX

= 150 kΩ 800 1000 1200 kHz

= 470 kΩ 350 kHz

= 470 kΩ 85 92 %

LED CURRENT REGULATION SPECIFICATIONS

VIN = 12 V,

Table 2.

Parameter Symbol Test Conditions Min Typ Max Unit

CURRENT SOURCE

SET

Adjustable LED Current1 I Constant Current Sink of 20 mA2 I Minimum Headroom Voltage2 V Current Matching Between Strings2 R LED Current Accuracy2 R Current Source Leakage Current 1 μA

FPWM GENERATOR

Dimming Frequency Range Dimming Frequency f

LED FAULT DETECTION

Open Fault Delay1 T

These electrical specifications are guaranteed by design.

Tested at TA = +25°C.

SHDN

= high, TA = −25°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.

Pin Voltage V

6 V ≤ VIN ≤ 21 V 1.16 1.2 1.24 V

SET

0 30 mA

LED

LED20

HR20

PWM

= 141.56 kΩ 19.4 20 20.6 mA

SET

= 141.56 kΩ 0.65 0.85 V

SET

= 141.56 kΩ −1.5 +1.5 %

SET

= 141.56 kΩ −3 +3 %

SET

6 V ≤ VIN ≤ 21 V 200 10,000 Hz

FPWM

= 50 kΩ, C

= 150 pF 820 1000 1180 Hz

FPWM

D_OPENFAULT

6.5 μs

Rev. 0 | Page 4 of 24

ADD5203

SMBUS SPECIFICATIONS

VIN = 12 V,

Table 3.

Parameter1 Symbol Test Conditions Min Typ Max Unit

SMBus INTERFACE

Data, Clock Input Low Level VIL 0.8 V Data, Clock Input High Level VIH 2.1 5.5 V Data, Clock Output Low Level VOL 0.4 V

SMBus TIMING SPECIFICATIONS

Clock Frequency Bus-Free Time Between Stop and Start Condition Hold Time After Start Condition2

Repeated Start Condition Setup Time

Stop Condition Setup Time

Data Hold Time

Data Setup Time

Clock Low Period

Clock High Period

Clock/Data Fall Time

Clock/Data Rise Time

These electrical specifications are guaranteed by design.

After this period, the first clock is generated.

SHDN

= high, TA = −25°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.

SMB

BUF

HD:STA

SU:STA

SU:STO

HD:DAT

SU:DAT

LOW

HIGH

4.7 μs

1 us

10 100 kHz

4.0 μs

4.7 μs

4.0 μs

300 ns

250 ns

4.7 μs

4.0 50 μs

300 ns

Rev. 0 | Page 5 of 24

ADD5203

GENERAL SPECIFICATIONS

VIN = 12 V,

Table 4.

Parameter Symbol Test Conditions Min Typ Max Unit

SUPPLY

Input Voltage Range VIN 6 21 V Quiescent Current IQ

Shutdown Supply Current ISD

VDD REGULATOR

VDD Regulated Output V

PWM INPUT

PWM Voltage High V PWM Voltage Low V PWM Input Range 200 10,000 Hz

THERMAL SHUTDOWN

Thermal Shutdown Threshold1 T Thermal Shutdown Hysteresis1 T

UVLO

VIN Falling Threshold V VIN Rising Threshold V

SHDN CONTROL

Input Voltage High VIH 2.0 V Input Voltage Low VIL 1.0 V SHDN Pin Input Current

These electrical specifications are guaranteed by design.

SHDN

= high, TA = −25°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.

6 V ≤ V 6 V ≤ V

6 V ≤ VIN ≤ 21 V 3.18 3.3 3.42 V

VDD_REG

≤ 21 V, SHDN = high

≤ 21 V, SHDN = low

2.2 5.5 V

PWM_HIGH

0.8 V

PWM_LOW

30 °C

SDHYS

UVLOF

UVLOR

falling 4.2 4.6 V

rising 5.0 5.6 V

SHDN

= 3.3 V

4.2 6.5 mA 40 160 μA

160 °C

6 μA

Rev. 0 | Page 6 of 24

ADD5203

ABSOLUTE MAXIMUM RATINGS

TA = 25°C, unless otherwise noted.

Table 5.

Parameter Rating

VIN −0.3 V to +23 V SW −0.3 V to +50 V SHDN, SDA, SCL, PWMI, SEL1, and SEL2 I

, FSLCT, COMP, R_FPWM, and C_FPWM −0.3 V to +3.6 V

SET

VDDIO −0.3 V to +3.7 V FB1, FB2, FB3, FB4, FB5, FB6, FB7, and FB8 −0.3 V to +50 V OVP −0.3 V to +3 V Maximum Junction Temperature (TJ max) 150°C Operating Temperature Range (TA) −25°C to +85°C Storage Temperature Range (TS) −65°C to +150°C Reflow Peak Temperature (20 sec to 40 sec) 260°C

−0.3 V to +6 V

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

THERMAL RESISTANCE

θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages.

Table 6. Thermal Resistance

Package Type θJA θ

28-Lead LFCSP_WQ 32.6 1.4 °C/W

Unit

ESD CAUTION

Rev. 0 | Page 7 of 24

ADD5203

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

COMP

VIN

FSLC

1PWMI

2SEL1

3SEL2

DDIO

5SDA

6SCL

7FB1

NOTES

1. NC = NO CONNEC T.

2. CONNECT THE EXPOSED PADDLE TO GND.

ADD5203

TOP VIEW

(Not to Scale)

FB2

FB3

FB4

SHDN

21 PGND

20 PGND 19 C_FPWM

18 R_FPWM

17 I

SET

16 NC

15 FB8

FB5

FB6

FB7

AGND

08717-003

Figure 3. Pin Configuration

Table 7. Pin Function Descriptions

Pin No. Mnemonic Description

1 PWMI PWM Signal Input. 2 SEL1 Dimming Mode Selection 1. 3 SEL2 Dimming Mode Selection 2. 4 VDDIO Internal Linear Regulator Output. This regulator provides power to the ADD5203. 5 SDA Serial Data Input/Output. 6 SCL Serial Clock Input. 7 FB1 Regulated Current Sink. Connect the bottom cathode of the LED string to this pin. 8 FB2 Regulated Current Sink. Connect the bottom cathode of the LED string to this pin. 9 FB3 Regulated Current Sink. Connect the bottom cathode of the LED string to this pin. 10 FB4 Regulated Current Sink. Connect the bottom cathode of the LED string to this pin. 11 AGND Analog Ground. 12 FB5 Regulated Current Sink. Connect the bottom cathode of the LED string to this pin. If unused, connect to GND. 13 FB6 Regulated Current Sink. Connect the bottom cathode of the LED string to this pin. If unused, connect to GND. 14 FB7 Regulated Current Sink. Connect the bottom cathode of the LED string to this pin. If unused, connect to GND. 15 FB8 Regulated Current Sink. Connect the bottom cathode of the LED string to this pin. If unused, connect to GND. 16 NC No Connection. 17 I

Full-Scale LED Current Set. A resistor from this pin to ground sets the LED current up to 30 mA.

SET

18 R_FPWM Dimming frequency adjustment pin with an external resistor. 19 C_FPWM Dimming frequency adjustment pin with an external capacitor. 20 PGND Power Ground. 21 PGND Power Ground. 22 OVP Overvoltage Protection. 23 SW Drain Connection of the Internal Power FET. 24 SW Drain Connection of the Internal Power FET. 25

SHDN

Shutdown Control for PWM Input Operation Mode. Active low. 26 VIN Supply Input. Must be locally bypassed with a capacitor to ground. 27 FSLCT Frequency Select. A resistor from this pin to ground sets the boost switching frequency from 350 kHz to 1 MHz. 28 COMP

Compensation for Boost Converter. A capacitor and a resistor are connected in series between ground and

this pin for stable operation and an optional capacitor can be connected from this pin to ground. EP Exposed Paddle. Connect the exposed paddle to ground.

Rev. 0 | Page 8 of 24

+ 16 hidden pages

ANALOG DEVICES ADD5203 Service Manual

FEATURES

FUNCTIONAL BLOCK DIAGRAM

APPLICATIONS

GENERAL DESCRIPTION

TABLE OF CONTENTS

REVISION HISTORY

CIRCUIT DIAGRAM

SPECIFICATIONS

STEP-UP SWITCHING REGULATOR SPECIFICATIONS

LED CURRENT REGULATION SPECIFICATIONS

SMBUS SPECIFICATIONS

GENERAL SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS

THERMAL RESISTANCE

ESD CAUTION

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS