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ADD5203
Service Manual
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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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2010 Analog Devices, Inc. All rights reserved.
ADD5203

TABLE OF CONTENTS

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
I
SET
FB1
28
17
7
UVP REF
REF
CURRENT
REFERENCE
LINEAR
REGULATOR
VOLTAGE
REFERENCE
UVP
COMP
ERROR
AMP
GM
HEADROOM CONTROL
CURRENT SOURCE 1
REF
LL
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
+
∑
+
R
S
CURRENT SENSE
SOFT START
TSD FAULT
OCP FAULT
OCP REF
23
SW
OVP REF
Q
R
SENSE
24
27
20
21
SW
FSLCT
PGND
PGND
8
FB2
FB3
FB4
FB5
FB6
FB7
9
10
12
13
14
15
CURRENT SOURCE 2
CURRENT SOURCE 3
CURRENT SOURCE 4
CURRENT SOURCE 5
CURRENT SOURCE 6
CURRENT SOURCE 7
CURRENT SOURCE 8FB8
11
AGND
REGISTER
REGISTER
ID REGISTER
FAU LT/STAT US
CURRENT SOURCE CONT ROLLER
REGISTER
DEVICE CONTRO L
BRIGHTNESS CONTROL
SMBus INTERFACE DUTY GENERATOR
PWMI DUTY
EXTRACTOR
OPERATION
MODE
SELECTION
PWM
OSCILLATOR
5
6
1
2
3
19
18
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
R
SW
R
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
F
= 470 kΩ 350 kHz
F
= 470 kΩ 85 92 %
F

LED CURRENT REGULATION SPECIFICATIONS

VIN = 12 V,
Table 2.
Parameter Symbol Test Conditions Min Typ Max Unit
CURRENT SOURCE
I
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
1
These electrical specifications are guaranteed by design.
2
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
R
LED20
R
HR20
R
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
1
These electrical specifications are guaranteed by design.
2
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.
f
SMB
t
BUF
t
HD:STA
t
SU:STA
t
SU:STO
t
HD:DAT
t
SU:DAT
t
LOW
t
HIGH
tF
t
R
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
1
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
IN
≤ 21 V, SHDN = low
IN
2.2 5.5 V
PWM_HIGH
0.8 V
PWM_LOW
SD
30 °C
SDHYS
V
UVLOF
V
UVLOR
falling 4.2 4.6 V
IN
rising 5.0 5.6 V
IN
I
SHDN
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
JC

ESD CAUTION

Rev. 0 | Page 7 of 24
ADD5203
V
T

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

COMP
VIN
FSLC
28
26
27
1PWMI
2SEL1
3SEL2
DDIO
4
5SDA
6SCL
7FB1
NOTES
1. NC = NO CONNEC T.
2. CONNECT THE EXPOSED PADDLE TO GND.
ADD5203
TOP VIEW
(Not to Scale)
8
9
10
FB2
FB3
FB4
VP
SW
O
SHDN
SW
23
22
24
25
21 PGND
20 PGND 19 C_FPWM
18 R_FPWM
17 I
SET
16 NC
15 FB8
11
12
13
14
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
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