Data Sheet
FEATURES
White LED driver based on an inductive boost controller
Wide input voltage range: 4.5 V to 40 V
Adaptive output voltage to minimize power dissipation
Adjustable operating frequency: 200 kHz to 1.2 MHz
Programmable UVLO
Programmable soft start time for boost converter
Programmable external MOSFET switching rising/falling time
Drives up to 4 LED current sinks with internal MOSFETs
Brightness control with PWM input
Adjustable LED current: 40 mA to 200 mA
Headroom control to maximize efficiency
LED dimming frequency: up to 25 kHz
PWM dimming at 300 Hz: 1000:1
Open-drain fault indicator
LED open and LED short fault protection
Thermal shutdown
Undervoltage lockout (UVLO)
24-lead, 4 mm × 4 mm LFCSP
Four-String, White LED Driver
for LCD Backlight Applications
ADD5211
GENERAL DESCRIPTION
The
ADD5211
is a four-string, white LED driver for backlight
applications based on high efficiency, current mode, step-up
converter technology. The boost controller drives an external
MOSFET switch for step-up regulation from an input voltage
of 4.5 V to 40 V and a pin adjustable operating frequency from
200 kHz to 1.2 MHz. An adjustable UVLO function is implemented
to reduce input current during power-off.
The
ADD5211
provides four regulated current sinks for uniform
brightness intensity. Each current sink can be driven from 40 mA
to 200 mA; the LED driving current is pin adjustable using an
external resistor. With an input PWM interface, the
ADD5211
drives up to four parallel strings of multiple series connected LEDs.
Additional features include LED short protection, LED open
protection, boost output short protection, overvoltage protection,
cycle-by-cycle current limit, and thermal shutdown for both the
IC and the LED array. An open-drain fault output is also included.
A programmable soft start is implemented to reduce inrush
current during startup.
APPLICATIONS
LCD monitor and TV LED backlights
Industrial lighting
APPLICATION CIRCUIT
VIN
+
UVLO
VDR
VIN GATE_P GATE_N
CS
RAMP
OFF ON
EN
PWM
PGND
OVP
FAULT
VDD
ADD5211
FB4
FB3
LSD
ISET
AGND FREQ
COMP
FB2
FB1
LGND
SS
Figure 1.
Rev. A
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Trademarks and registered trademarks are the property of their respective owners.
10555-001
ADD5211
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Application Circuit ........................................................................... 1
Revision History ............................................................................... 2
Detailed Functional Block Diagram .............................................. 3
Specifications..................................................................................... 4
General Specifications ................................................................. 4
Step-Up Switching Controller Specifications ........................... 5
LED Current Regulation Specifications .................................... 5
Absolute Maximum Ratings ............................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution .................................................................................. 6
Data Sheet
Pin Configuration and Function Descriptions..............................7
Typical Performance Characteristics ..............................................8
Theory of Operation ...................................................................... 10
Current Mode, Step-Up Switching Controller ....................... 10
LED Current Regulation ........................................................... 11
Fault Protection .......................................................................... 12
Applications Information .............................................................. 14
Layout Guidelines....................................................................... 14
Boost Component Selection ..................................................... 14
Typical Application Circuits ......................................................... 17
Outline Dimensions ....................................................................... 18
Ordering Guide .......................................................................... 18
REVISION HISTORY
10/2017—Rev. 0 to Rev. A
Changed CP-24-7 to CP-24-15 .................................... Throughout
Change to Operating Temperature Range (T
A
), Table 4 ............. 6
Updated Outline Dimensions ....................................................... 18
Changes to Ordering Guide .......................................................... 18
10/2013—Revision 0: Initial Version
Rev. A | Page 2 of 20
Data Sheet
DETAILED FUNCTIONAL BLOCK DIAGRAM
VDR
OVP
BOOST CONTROL
PWM
COMP
ERROR
AMP
S
R
R
Q
SWITCH
DRIVER
ADD5211
GATE_P
GATE_N
FB_REF
FB_MIN
COMP
g
m
PGND
FREQ
OSC
STARTUP
SOFT START
RAMP
DREF
DCOMP
OVP_REF
OVP
OVP
BOOST
SCP_REF
SCP
POR
CURRENT SENSE
SS
CS
+
+
RAMP
ADD5211
OVP
×10
POR
LSD
FAULT
FAULT
DETECTOR
LINEAR
REGULATOR
THERMAL
SHUTDOWN
OPEN
LED
DETECTOR
SHORT
LED
DETECTOR
UNUSED
STRING
DETECTOR
VDR
VIN
DEVICE
ENABLE
FB_MIN
STRING
VOLTAGE
DETECTOR
EN
500kΩ
AGND
AGND
UVLO
UVLO
DETECTOR
BAND GAP
REFERENCE
CURRENT SOURCE 1
FB1
VOLTAGE
REGULATOR
CURRENT SOURCE 2
FB2
VDD
POR
CURRENT SOURCE 3
FB3
PWM
500kΩ
AGND
CONTROL LOGIC
BOOST CONTROL
STARTUP
DIMMING CONTROL
VDD
CURRENT SOURCE 4
FB4
THERMAL
SHUTDOWN
BOOST
SHORT
REF
DIMMING CONTROL
LGND
10555-002
ISET
Figure 2.
Rev. A | Page 3 of 20
ADD5211
SPECIFICATIONS
V
IN
= 12 V, EN = 3.3 V, T
J
= −40°C to +125°C, unless otherwise noted. Typical values are at T
A
= 25°C.
Data Sheet
GENERAL SPECIFICATIONS
Table 1.
Parameter
SUPPLY
Input Voltage Range
Quiescent Current
Shutdown Supply Current
VIN Rising Threshold
VIN Falling Threshold
VDR REGULATOR
Regulated Output
Dropout Voltage
VDD REGULATOR
Regulated Output
PWM INPUT
Input High Voltage
Input Low Voltage
PWM Input Current
PWM High to LED Turn-On Delay
1
PWM Low to LED Turn-Off Delay
1
EN CONTROL
EN Voltage High
EN Voltage Low
EN Pin Input Current
UNDERVOLTAGE LOCKOUT
UVLO Threshold (Rising)
UVLO Hysteresis
FAULT
Sink Resistance
Fault Pin Leakage Current
LED SHORT DETECTION
LED Short Detection Enable Threshold
LED Short Gain
LED Short Gain Control Range
1
LED FAULT DETECTION DELAY
1
LED Open Fault Delay
LED Short Fault Delay
OVERVOLTAGE PROTECTION
Overvoltage Threshold (Rising)
Overvoltage Hysteresis
Overvoltage Pin Leakage Current
Output Short-Circuit Threshold (Falling)
Output Short-Circuit Recovery (Rising)
THERMAL SHUTDOWN
1
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
1
Symbol
V
IN
I
Q
I
SD
V
UVLOR_VIN
V
UVLOF_VIN
V
VDR_REG
V
VDR_DROP
V
VDD_REG
V
PWM_HIGH
V
PWM_LOW
Test Conditions/Comments
Min
4.5
Typ
Max
40
6
1
4.3
Unit
V
mA
µA
V
V
V
mV
V
V
V
µA
µs
µs
V
V
µA
V
mV
Ω
µA
V
V
µs
µs
2.8
EN = 0 V
Minimum V
IN
for startup
3.2
4.75
V
IN
= 4.5 V
3.0
2.2
PWM = 5 V
11
1.6
0.8
2.2
EN = 5 V
1.10
13
1.19
100
40
4
3.65
5.1
350
3.3
5.45
580
3.6
8
0.8
30
17
0.8
30
1.27
100
1.5
VDD
13
2.0
V
LSD
LSD = 1.0 V
2.2
7.5
0.3
2.5
10
5
15
OVP_REF
OVP_HYS
V
SCPF
V
SCPR
T
SD
T
SDHYS
2.3
2.5
100
100
150
150
25
2.7
200
V
mV
nA
mV
mV
°C
°C
Guaranteed by design.
Rev. A | Page 4 of 20
Data Sheet
STEP-UP SWITCHING CONTROLLER SPECIFICATIONS
Table 2.
Parameter
BOOST FREQUENCY OSCILLATOR
Switching Frequency Range
Switching Frequency
PWM COMPARATOR
Maximum Duty Cycle
Leading Edge Blanking Time
CURRENT SENSE LIMIT COMPARATOR
Current-Limit Threshold
SLOPE COMPENSATION
Peak Slope Compensation Ramp
ERROR AMPLIFIER
Transconductance
Output Resistance
COMP Sink Current
COMP Source Current
MOSFET DRIVER
Source Voltage
Gate On Resistance
Gate Off Resistance
Rising Time
Falling Time
SOFT START
Soft Start Pin Current
Symbol
Test Conditions/Comments
Min
200
280
89
Typ
Max
1200
430
98
ADD5211
Unit
kHz
kHz
%
ns
mV
µA
µA/V
MΩ
µA
µA
V
Ω
Ω
ns
ns
µA
f
SW
R
FREQ
= 50 kΩ
R
FREQ
= 50 kΩ
360
94
145
345
45
570
72
400
400
CS
LIMIT
Independent of duty cycle
R
RAMP
= 5 kΩ
275
400
g
m
R
8 V < V
IN
< 40 V
R
DS_GATE_P
R
DS_GATE_N
t
R
t
F
I
SS
C = 1 nF
C = 1 nF
5.1
5.8
2.4
26
21
2.1
LED CURRENT REGULATION SPECIFICATIONS
Table 3.
Parameter
CURRENT SINK
Current Sink Range
Current Sink
String-to-String Tolerance
1
Current Accuracy
2
Minimum Headroom Voltage
Off Current
Off State Clamping Current
1
Symbol
I
LED
I
LED100
ΔI
FB100
ΔI
LED100
V
HR
I
OFF
I
CLAMP
Test Conditions/Comments
Min
40
98
Typ
Max
200
102
2.5
2.0
0.85
1.5
80
Unit
mA
mA
%
%
V
µA
µA
R
SET
= 15 kΩ, T
A
= 25°C
R
SET
= 15 kΩ, T
A
= 25°C
R
SET
= 15 kΩ, T
A
= 25°C
R
SET
= 15 kΩ, T
A
= 25°C
V
FB
= 40 V, EN = 0 V
V
FB
= 55 V, EN = 0 V
0.45
0.4
4
0.55
20
String-to-string tolerance is the greatest delta between FBx currents with respect to the average of the FBx currents.
I
I
FB100(MIN)
−
I
LED100
FB100(MAX)
−
I
LED100
∆
I
FB100
=
Max
×
100% :
×
100%
I
LED100
I
LED100
2
where
I
FB100
is the LED current of each string.
Current accuracy is the delta between average current, I
LED100
,
and 100 mA with respect to 100 mA.
∆
I
LED100
=
I
LED100
−
100 mA
100 mA
×
100%
where
I
LED100
=
I
FB1
+
I
FB2
+
I
FB3
+
I
FB4
4
Rev. A | Page 5 of 20
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