FEATURES
TYPICAL APPLICATION CIRCUITS
VCC
NTC
ADP8140
REG
ENABLE
FAULT
DIM
EN
SINK1
FAULT
SINK2
FB_OUT SINK3
COMP
ISET
SINK4
VO_SNS
EXPOSED PAD
Figure 1. ADP8140 Used with Shunt Regulator
AGND VCC
FB
BST
ADP2441 BUCK
REGULATOR
COMP
PGND
PGOOD FREQ
ADP8140
VIN
VIN
VT
DIM
SINK1
FAULT
SINK2
FB_OUT
SINK3
ISET
SS
MIN
EN
COMP
VIN
SW
EN
MODE
High brightness LED lighting
Large format LED backlighting
VT
MODE
REG
APPLICATIONS
MIN
VIN
10935-001
Highly integrated feature set for a high brightness LED
driver solution with minimal external components
4 current sink channels with an adjustable current from
125 μA to 500 mA
Analog and pulse-width modulation (PWM) dimming inputs
Analog and PWM LED current outputs
2% (maximum) matching between LED channels
5% (maximum) LED current accuracy
Operates from VIN of 3 V to 30 V; higher voltages easily
accomplished with an external Zener diode
Operates with LED anode supply voltages up to 100 V dc
Feedback output controls external power source for optimal
efficiency and safety
Multiple ADP8140 IC operation in parallel to control one
power supply
Integrated error amplifier for secondary side control of
isolated power supplies
Easy connection of a temperature thermistor or light sensor
Provides robust protection of the entire system
Power supply overvoltage protection
LED overtemperature protection
LED short-circuit protection
LED open-circuit protection
IC overtemperature protection
Shorted ISET protection
Open ISET and EN protection
Standby mode for low current consumption
Fault indicator output
Small, thermally enhanced, LFCSP package (4 mm × 4 mm)
SINK4
VO_SNS
EXPOSED PAD
10935-039
Data Sheet
4-Channel High Current LED Driver with
Adaptable Power Control
ADP8140
Figure 2. ADP8140 Used with Buck
GENERAL DESCRIPTION
The ADP8140 provides high current control of up to four LED
drivers. Each driver can sink up to 500 mA. The sink current is
programmed for all four drivers with one external resistor.
The device features a feedback output that controls an external
power supply for optimal efficiency. The ADP8140 also protects
the LEDs, power supply, and itself against thermal events, short
Rev. B
circuits, overvoltages, and LED open circuits. Multiple
ADP8140 ICs are easily connected in parallel to drive additional
LED strings or higher current LEDs. The ADP8140 is available
in a small, thermally enhanced, lead frame chip scale package
(LFCSP).
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ADP8140
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
MODE Pin Operation................................................................ 13
Applications ....................................................................................... 1
Power Control Modes ................................................................ 13
Typical Application Circuits............................................................ 1
Dimming the LED Current ....................................................... 14
General Description ......................................................................... 1
Reducing the LED Current with the DIM Pin ....................... 15
Revision History ............................................................................... 2
Dimming LEDs with the VT Pin ............................................. 15
Specifications..................................................................................... 3
Fault Protections ......................................................................... 15
Absolute Maximum Ratings............................................................ 6
LED Open-Circuit and Short-Circuit Protection .................. 16
Maximum Temperature Ranges ................................................. 6
Die Temperature Protection ..................................................... 17
Thermal Resistance ...................................................................... 6
Using Multiple ADP8140 ICs ................................................... 17
ESD Caution .................................................................................. 6
Operating the ADP8140 from Higher Input Voltages .......... 18
Pin Configuration and Function Descriptions ............................. 7
Effect of LED VF Mismatch ....................................................... 18
Typical Performance Characteristics ............................................. 8
Managing the Power Dissipation of the ADP8140 ................ 19
Theory of Operation ...................................................................... 11
Layout Guidelines....................................................................... 19
Start-Up Sequence ...................................................................... 11
Ordering Options ....................................................................... 19
Current Sinks .............................................................................. 12
Outline Dimensions ....................................................................... 23
Power Control Operation .......................................................... 12
Ordering Guide .......................................................................... 23
REVISION HISTORY
9/2020—Rev. A to Rev. B
Changes to Figure 36 ...................................................................... 22
9/2018—Rev. 0 to Rev. A
Updated Outline Dimensions ....................................................... 23
Changes to Ordering Guide .......................................................... 23
2/2015—Revision 0: Initial Version
Rev. B | Page 2 of 23
Data Sheet
ADP8140
SPECIFICATIONS
VIN = 12 V, EN = DIM = VT = 3.0 V, MIN = MODE = 0 V. Typical values are at TJ = 25°C and are not guaranteed. Minimum and
maximum limits are guaranteed from TJ = −40°C to +125°C, unless otherwise noted.
Table 1.
Parameter
SUPPLY
Input Voltage
Operating Range
Undervoltage Lockout
Quiescent Current
During Standby
During Operation
REG Output
Output Voltage
Source Current
Load Regulation
FEEDBACK OUTPUT
FB_OUT Error Amplifier (EA)
Accuracy
FB_OUT NMOS Pull-Down
Current
FB_OUT Stage Gain
FB_OUT Fault Current
Amplifier Transconductance
Amplifier Transconductance
Output
Source
Sink
Resistance
Low Gain EA
Low Gain Bandwidth
ISET
Accuracy
Symbol
Test Conditions/Comments
VIN
VUVLO
EN = 0 V, VIN = 3.3 V to 30 V
EN = 3 V, VIN = 3.3 V to 30 V, RSET = 71.5 kΩ
VREG1
VREG2
IREGMAX
VIN = 3.3 V to 30 V, IREG = 1 mA
VIN = 3 V, IREG = 1 mA
VIN = 3.3 V to 30 V
VIN = 3.3 V to 30 V, IREG = 0.1 mA to 15 mA
VEA(450)
GFB
IFB_FC
COMPGM
COMPSOURCE
COMPSINK
COMPRO
GBUFF
SINKx = 0 V, FB_OUT = 3 V
Force 1.2 V and 1.3 V on COMP, measure FB_OUT
current (FB_OUT = 12 V)
Fault activated, FB_OUT = 30 V
2.85
2.85
15
Max
Unit
2.85
30.0
2.95
V
V
200
4.1
4.5
μA
mA
3.15
V
V
mA
mV/mA
430
450
476
mV
324
12.0
350
15.0
380
18.0
mV
mA
12500
17000
22000
μmho
30
0.04
60
1
120
μA
μmho
COMP pin output source current
COMP pin output sink current
3.6
ILED_500
ILED_350
ILED_100
ILED_35
RSET = 5.11 kΩ, SINKx = 600 mV
RSET = 7.32 kΩ, SINKx = 600 mV
RSET = 25.5 kΩ, SINKx = 600 mV
RSET = 71.5 kΩ, SINKx = 600 mV
ISET = GND
ISET = open
475
332.5
95
33.0
500
VHR_500
RSET = 5.11 kΩ, ILED = 95% × ILED_500
Current at 350 mV
VHR_350
IHR_350
Sink Matching
At 500 mA Current
At 350 mA Current
At 100 mA Current
At 35 mA Current
RSET = 7.32 kΩ, ILED = 95% × ILED_350
Maximum guaranteed current using the 350 mV
reference option
Matching = (ISINK_MAX − ISINK_MIN)/(ISINK_MAX + ISINK_MIN) × 100
IMATCH500
IMATCH350
IMATCH100
IMATCH35
Rev. B | Page 3 of 23
3.0
2.95
0.75
Gain in buffer mode (MODE = 30.1 kΩ to GND)
MODE = 30.1 kΩ to GND
Shorted Current
Open Current
CURRENT SINKS
Current Sink Headroom Voltage
at Maximum Current
Typ
3.0
IQ(STBY)
IQ(ACTIVE)
VEA(350)
IFB_PD
Min
110
1.5
20
3.9
100
μA
mA
MΩ
4.2
kHz
500
350
100
35
570
15
525
367.5
105
37.5
620
17
mA
mA
mA
mA
mA
mA
320
430
mV
210
324
mV
mA
0.2
0.25
0.25
0.3
2
2
2
2
%
%
%
%
350
ADP8140
Parameter
SINKx Leakage Current
Channel Clamp Threshold
Low
High
Channel Clamp Current
Low
Data Sheet
Symbol
ISINK(LKG)
Test Conditions/Comments
SINKx pin = 4 V
Min
Typ
8
Max
12
Unit
μA
VCH_CLMP_LOW
Threshold on SINKx to trigger VCH_CLMP_LOW, MIN pin =
GND
Threshold on SINKx to trigger VCH_CLMP_HIGH
7.4
7.75
8.1
V
14.5
15.1
15.7
V
315
350
385
mA
430
510
600
mA
VCH_CLMP_HIGH
ICLMP_LOW
High
Channel Clamp Hysteresis
Lowest SINKx Current
ICLMP_HIGH
VCH_CLMP_HYS
INPUT CONTROLS
Input Threshold (Low)
Input Threshold (High)
EN Input Resistance
MODE Pin Pull-Up Current
MODE Threshold 1, 30.1 kΩ
VIL
VIH
REN
IM
VM1
MODE Threshold 2, 52.3 kΩ
VM2
MODE Threshold 3
VM3
LED SCALING CONTROLS
DIM and VT Limit Voltage
Threshold for increasing mode voltage to enter dc
buffer operation
Threshold for increasing mode voltage to enter
PWM buffer operation
Threshold for increasing mode voltage to enter
PWM EA operation
VMIN_HYS
VMIN_PWM
0.85
V
1.25
1.3
1.35
V
VT (and DIM if MODE = GND) voltage to produce
100% output current
ILED_DIM1/ILED_100, VT = 1 V, MIN = 0 V, RSET = 25.5 kΩ
ILED_DIM2/ILED_100, DIM = 0.2 V, MODE = GND, RSET =
25.5 kΩ
ILED_DIM3/ILED_100, DIM = 50%,140 Hz, MODE = REG,
RSET = 25.5 kΩ
1.9
2.0
2.1
V
48
9.4
50
10
52
10.4
%
%
48
50
52
%
0.6
1
40
μA
kHz
mV
V
MODE = REG
0.14
Voltage on MIN pin at which VT changes from
scaling LED current to pulsing LED current
Delay from VT low to high (or high to low) to LED
current low to high (or high to low), MIN = REG
2.2
VVO_SNS_TH
VVO_SNS_HYS
IVO_SNS
VSFD_OPEN
Threshold for VO_SNS comparator
Hysteresis for VO_SNS comparator
1.176
E
A
E
A
0.8
1.14
A
A
0.75
Threshold for FAULT comparator
Hysteresis for FAULT comparator
VO_SNS and FAULT shutdown noise filter
Fault activated
E
A
24
0.45
VFAULT_TH
VFAULT_HYS
tFAULT
FAULTPD
A
A
400
20
0.4
TFBTHRES
TSDTHRES
TSDHYS
E
A
15
0.35
V
V
kΩ
μA
V
EN = 1.2 V
ILED_DIM3
THERMAL FOLDBACK
(INTERNAL)
Thermal Foldback Threshold
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
FAULT DETECTION
FAULT Threshold
FAULT Hysteresis
FAULT Filter
FAULT Pull-Down Resistance
VO_SNS
Threshold
Hysteresis
Leakage Current
Open SINKx Fault Threshold
E
A
V
μA
0.6
ILED_DIM1
ILED_DIM2
VT Pull-Up Current Source
DIM Pin Frequency Range
MIN Comparator Hysteresis
MIN Pin PWM Mode
Threshold
PWM Delay and Rise/Fall Time
1.2
125
1.1
VTLIMIT
Dimming Accuracy
Channel pull-down current when SINKx >
CHCLMP_LOW, RSET = 7.32 kΩ
Channel pull-down current when SINKx >
CHCLMP_HIGH
Hysteresis after either channel clamp is triggered
Output current for DIM = 0 V and RSET = 10 kΩ (see
Figure 15)
A
E
A
A
E
A
A
E
A
A
7
55
2.3
2.4
20
μs
135
150
20
°C
°C
°C
1.2
100
10
15
1.26
1.2
50
1.224
20
50
SINKx pin voltage threshold to remove a sink from
the feedback loop after a VOUT_OVP fault
Rev. B | Page 4 of 23
80
V
mV
μs
Ω
V
mV
nA
mV
Data Sheet
Parameter
Channel Overvoltage
Threshold
Channel Overvoltage
Hysteresis
Short SINKx Fault Threshold
ADP8140
Symbol
VCH_OVP
Test Conditions/Comments
Threshold on SINKx to trigger CH_OVP fault
VCH_OVP_HYS
Hysteresis after VCH_OVP is triggered
1.2
V
VSFD_SHORT
SINKx pin voltage threshold to remove a sink from
the feedback loop after a CH_OVP fault
525
mV
Rev. B | Page 5 of 23
Min
5.3
Typ
5.7
Max
6.1
Unit
V
ADP8140
Data Sheet
ABSOLUTE MAXIMUM RATINGS
MAXIMUM TEMPERATURE RANGES
Table 2.
Parameter
VIN, FB_OUT to GND
SINKx to GND
MODE, COMP, REG, MIN, DIM, VT, ISET to
GND
EN, FAULT, VO_SNS to GND
Operating Ambient Temperature Range
Operating Junction Temperature Range
Maximum Junction Temperature
Storage Temperature Range
Soldering Conditions
ESD (Electrostatic Discharge)
Human Body Model (HBM)
Charged Device Model (CDM)
E
A
1
A
Rating
−0.3 V to +31 V
−0.3 V to +21 V
−0.3 V to +3.6 V
−0.3 V to +6.0 V
–40°C to +105°C1
–40°C to +125°C
150°C
–45°C to +150°C
JEDEC J-STD-020
±1.5 kV
±500 V
The maximum operating junction temperature (TJ(MAX)) supersedes the
maximum operating ambient temperature (TA(MAX)). See the Maximum
Temperature Ranges section for more information.
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
The maximum operating junction temperature (TJ(MAX))
supersedes the maximum operating ambient temperature
(TA(MAX)). Therefore, in situations where the ADP8140 is
exposed to poor thermal resistance and a high power dissipation (PD), the maximum ambient temperature may need to be
derated. In these cases, the ambient temperature maximum can
be calculated with the following equation:
TA(MAX) = TJ(MAX) − (θJA × PD(MAX))
THERMAL RESISTANCE
θJA (junction to air) is specified for the worst-case conditions,
that is, a device soldered in a circuit board for surface-mount
packages. The θJA, θJB (junction to board), and θJC (junction to
case) are determined according to JESD51-9 on a 4-layer
printed circuit board (PCB) with natural convection cooling.
The LFCSP exposed pad must be soldered to GND.
Table 3. Thermal Resistance
Package Type
16-Lead LFCSP
ESD CAUTION
Absolute maximum ratings apply individually only, not in
combination. Unless otherwise specified, all voltages are
referenced to GND.
Rev. B | Page 6 of 23
θJA
33.2
θJB
12.4
θJC
2.4
Unit
°C/W
Data Sheet
ADP8140
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
VIN
REG
MODE
EN
FAULT
FB_OUT
COMP
ISET
1
2
3
4
5
6
7
8
ADP8140
EXPOSED PAD
(GND)
16
15
14
13
12
11
10
9
TOP VIEW
(Not to Scale)
MIN
VT
DIM
SINK1
SINK2
SINK3
SINK4
VO_SNS
10935-003
PIN 1 INDICATOR
(LASER MARKING)
NOTES
1. CONNECT THE EXPOSED PAD OF THE LFCSP TO GROUND.
Figure 3. Pin Configuration
Table 4. Pin Function Descriptions
Pin No.
1
2
3
Mnemonic
VIN
REG
MODE
4
EN
5
FAULT
E
A
Description
Supply Voltage Input (3.0 V to 30 V).
Regulated 3.0 V (Typical) Source. Connect a 1.0 μF (or greater) capacitor from REG to ground.
Operation Mode. If MODE is connected to ground, the device is placed in dc EA operation. If MODE is connected to
REG, the device is placed in PWM EA operation. If MODE is connected via a 30.1 kΩ resistor to ground, the device is
placed in dc low gain buffer operation. If MODE is connected via a 52.3 kΩ resistor to ground, the device is placed
in PWM low gain buffer operation. The MODE pin is read only once at power-up (when VIN exceeds 3 V). Any
changes to the MODE pin after applying power are ignored. See the MODE Pin Operation section for more
information.
Enable Input. Pull high (above VIH(MIN)) to enable the device. EN is internally pulled low with a 400 kΩ (typical)
resistor.
Fault Output. This pin must be connected to an external pull-up resistor. If using multiple ADP8140 ICs in parallel,
all FAULT pins must be connected together.
Feedback Output. The FB_OUT pin is a control signal for the external power stage. The action of this pin depends
on the MODE setting.
Compensation Pin for EA. The COMP pin is a control signal for the external power stage. COMP is a dual function
pin. The action of this pin depends on the MODE setting.
Output Current Setting. Connect a resistor to ground to set the output current. If left floating, the current sinks are
set to 15 mA.
Overvoltage Protection Sensing Input. Connect the VO_SNS pin through a resistor divider to the top of the LED
strings, or connect it to ground to disable overvoltage sensing.
Current Sink for LED Channel 4.
Current Sink for LED Channel 3.
Current Sink for LED Channel 2.
Current Sink for LED Channel 1.
Dim Input. The DIM pin scales the LED current from the PWM signal or dc voltage. The action of this pin depends
on the MODE setting.
Voltage Threshold. VT is a dual function pin. If MIN < 2.2 V at startup, VT is an analog current reduction pin. A
voltage on VT scales the LED current. If MIN is connected to REG at startup, a PWM signal applied to VT pulses the
LED current.
Minimum Voltage Threshold. If MIN < 2.2 V at startup, the MIN voltage sets the minimum voltage threshold for the
VT pin. VT voltages below the MIN voltage shuts down the power stage. If MIN is connected to REG at startup, a
PWM signal applied to VT pulses the LED current.
Exposed Pad (Ground). Connect the exposed pad of the LFCSP to ground.
E
A
6
FB_OUT
7
COMP
8
ISET
9
VO_SNS
10
11
12
13
14
SINK4
SINK3
SINK2
SINK1
DIM
15
VT
16
MIN
EPAD (GND)
A
Rev. B | Page 7 of 23
ADP8140
Data Sheet
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 12 V, EN = DIM = VT = 3.0 V, MIN = MODE = 0 V, VSINKx = 450 mV, TA = 25°C, unless otherwise noted.
4.5
500
4.0
–40°C
3.5
+25°C
3.0
400
+85°C
ISINK (mA)
+125°C
2.5
IQ (mA)
–40°C
+25°C
+125°C
2.0
300
200
1.5
1.0
100
0
5
10
15
20
25
30
35
VIN (V)
0
0.01
Figure 4. Typical Operating Current vs. VIN, EN = 3 V, RSET = 71.5 kΩ
0.1
VSINK (V)
1
10935-007
0
10935-004
0.5
Figure 7. Typical Sink Current vs. Sink Voltage, RSET = 5.11 kΩ
400
4.9
–40°C
+25°C
+85°C
+125°C
4.7
350
300
–40°C
+25°C
+85°C
+125°C
4.5
ISINK (mA)
4.1
200
150
3.9
100
3.5
5
10
20
0
0.01
40
0.1
VSINK (V)
RSET (kΩ)
Figure 8. Typical Sink Current vs. Sink Voltage, RSET = 7.32 kΩ
120
250
100
200
80
ISINK (mA)
300
150
100
50
0
–40°C
+25°C
+85°C
+125°C
60
40
IQ –40°C
IQ +25°C
IQ +85°C
IQ +125°C
0
5
10
15
20
25
VIN (V)
20
30
0
0.01
10935-006
IQ (STBY) (µA)
Figure 5. Typical Operating Current vs. RSET
1
10935-008
50
10935-005
3.7
0.1
VSINK (V)
1
Figure 9. Typical Sink Current vs. Sink Voltage, RSET = 25.5 kΩ
Figure 6. Typical Standby Current vs. VIN, EN = 0 V
Rev. B | Page 8 of 23
10935-009
IQ (mA)
250
4.3
Data Sheet
ADP8140
3.20
1.0
3.10
3.05
0.6
VREG (V)
ISINK MATCHING (%)
0.8
–40°C
+25°C
+85°C
+125°C
3.15
–40°C
+25°C
+125°C
0.4
3.00
2.95
2.90
0.2
0.5
0.6
0.7
0.8
0.9
1.0
VSINK (V)
2.80
10935-010
0
0.4
10935-013
2.85
0
10
15
20
25
30
VIN (V)
Figure 13. REG Voltage vs. Input Voltage
Figure 10. Typical Sink Current Matching vs. Sink Voltage, RSET = 5.11 kΩ
500
1.0
–40°C
+25°C
+85°C
+125°C
450
–40°C
+25°C
+85°C
+125°C
0.8
400
350
0.6
ISINK (mA)
0.4
300
250
200
150
10935-014
100
0.2
50
0.5
0.7
0
10935-011
0
0.3
0.9
VSINK (V)
5
35
45
55
65
75
Figure 14. Sink Current vs. RSET (DIM = 3 V)
1.0
300
–40°C
+25°C
+85°C
+125°C
250
200
0.6
ISINK (uA)
ISINK MATCHING (%)
25
RSET (kΩ)
Figure 11. Typical Sink Current Matching vs. Sink Voltage, RSET = 7.32 kΩ
0.8
15
0.4
150
100
0.2
10935-012
0
0.15
–40°C
+25°C
+85°C
+125°C
50
0.35
0.55
0.75
0
0.95
VSINK (V)
5
10
20
40
RSET (kΩ)
Figure 12. Typical Sink Current Matching vs. Sink Voltage, RSET = 25.5 kΩ
Rev. B | Page 9 of 23
Figure 15. Sink Current vs. RSET (DIM = 0 V)
80
10935-015
ISINK MATCHING (%)
5
ADP8140
Data Sheet
ISINK AS A PERCENT
OF FULL-SCALE CURRENT (%)
100
VT
–40°C
+25°C
+85°C
+125°C
80
1
60
ISINK
40
20
0
0.5
1.0
1.5
2.0
2.5
3.0
DIM OR VT VOLTAGE (V)
Figure 16. Typical Sink Current vs. DIM or VT Voltage (MODE = 0, MIN = 0 V)
CH1 1V
CH4 100mA
10935-018
0
10935-016
4
1.0ms
Figure 18. Typical Sink Current Waveforms with PWM on VT Pin (MIN = 3 V)
100
EN
–40°C
+25°C
+85°C
+125°C
80
70
1
FAULT
2
60
50
COMP
40
3
30
10
0
0
10
20
30
40
50
60
70
80
90
4
CH1 2V
100
CH2 2V
CH3 1V
CH4 200mA
2.00ms
VT DUTY CYCLE (%)
Figure 17. Typical Average Sink Current vs. VT Duty Cycle
(MIN = 3 V, VT Frequency = 120 Hz)
Figure 19. Start-Up Sequence (See Figure 1 Setup)
Rev. B | Page 10 of 23
10935-019
ISINK
20
10935-017
AVERAGE ISINK AS A PERCENT
OF MAX CURRENT (%)
90
Data Sheet
ADP8140
THEORY OF OPERATION
needed. In this operation, with EN low, the ADP8140 consumes
no more than 200 μA (typical). A 400 kΩ (typical) resistor from
EN to GND ensures that the ADP8140 is shut down in the
event of an open connection on the EN pin.
The ADP8140 provides high current control of up to four LED
channels. Each driver can sink up to 500 mA. One external
resistor programs the sink current for all four channels. The
device features a feedback output that controls an external
power supply for optimal efficiency. The ADP8140 also protects
the LEDs, power supply, and itself against thermal events, short
circuits, and LED open circuits. Multiple ADP8140 ICs are
easily connected in parallel to drive additional LED strings or
higher current LEDs.
When EN also goes high, the power stage starts up and the
current sinks are enabled. There is an approximate 8 ms delay
after EN goes high. When the sinks are enabled, the FAULT pin
is released and the COMP and FB_OUT pins begin their
normal regulation. When EN goes low, the SINKx pins are left
on for another 100 μs to discharge any voltage from the power
stage output. The device then enters low current consumption
operation.
E
A
A
START-UP SEQUENCE
To start the ADP8140, VIN must be applied in excess of the
UVLO threshold and the EN pin must be high. However, even
with EN low, the REG pin produces a constant 3.0 V (typical)
on its output. REG can be used as a low current supply, as
VOUT
REG
SINK1
SINK3
SINK2
SINK4
COMP
FB_OUT
VT
VEA(REF)
SCALE
MIN
AND
MAX
NTC
MIN
ID1
MIN
MAX
MIN
IM
MODE
DIM
5.7V
ID2
DIM
CONTROL
SINK
CONTROL
SHUTDOWN
ID3
ISET
REDUCE CURRENT
WHEN DIE TEMP
> 135°C
DIE TEMP
SENSE
CH_OVP
ID4
8V/15V
SINKx < 550mV?
IF SO, REMOVE
FROM FB LOOP
SINK EN
EN
NOISE
FILTER
10 µs
RESET
ALL FAULTS
400kΩ
REG
UVLO
VIN
3.0V TO 30V
ISET SHORT
CIN
TSD
VREG_OK
REG
1.2V
FAULT
VT < MIN
3.0V
VOUT
NOISE FILTER
6V
10 µs
VOUT_OVP
SINKx < 75mV?
IF SO, REMOVE
FROM FB LOOP
1.2V
16-LEAD EXPOSED PAD THERMALLY ENHANCED PACKAGE
Figure 20. Detailed Block Diagram
Rev. B | Page 11 of 23
GND
(EXPOSED PAD)
10935-022
VO_SNS
ADP8140
Data Sheet
VIN
VUVLO
UVLO
3.0V
REG
EN
SINK_EN
(INTERNAL)
SHUTDOWN
VREG OK AND UVLO OK AND EN HIGH
~8ms
SHUTDOWN
100µs
DETERMINE MODE STATE
MODE_STATE
(INTERNAL)
DETERMINE (ONE OF 4 STATES) UNTIL REG OR VIN POWERS DOWN
FAULT
(EXT RESISTOR
PULL-UP)
COMP
(EA CONFIG)
10935-023
FB_OUT
(EA CONFIG)
COMP
(BUFFER CONFIG)
Figure 21. Start-Up Timing and Signals
CURRENT SINKS
per sink to 570 mA (typical) and shuts down the power stage
(FAULT goes low and FB_OUT and COMP are disabled).
E
The ADP8140 contains four internal current sinks. Each
current sink is capable of delivering 125 μA to 500 mA. To
ensure accurate regulation, the voltage on the current sinks
must be greater than the maximum headroom voltage given in
Table 1. For additional information on the headroom voltage,
see Figure 7 to Figure 9. All current sinks have their maximum
current set by the external resistor, RSET. To determine the value
of RSET, use Equation 1. A graph of sink current vs. RSET is shown
in Figure 14.
RSET (kΩ)
2560
I SINK (mA)
(1)
Multiple sinks can be combined together for higher currents per
LED string. For example, two sinks can be shorted together to
drive two strings of LEDs, each at up to 1 A, or four sinks
combined to drive one string of LEDs at up to 2.0 A.
A resistor must always be connected to the ISET pin. However,
in the event that ISET is accidentally left open, the ADP8140
defaults to a typical current of 15 mA (typical) per sink. If ISET
is accidentally shorted to GND, the ADP8140 limits the current
A
A
Each current sink has a maximum rated voltage of 20 V.
However, the maximum output voltage driving all the current
sinks, through the LEDs, is allowed to exceed 20 V. The LEDs
drop enough voltage so that the SINKx voltage remains close to
the FB_OUT EA accuracy value, VEA(REF) (where REF is the
reference voltage). Because the ADP8140 controls the power
stage, the voltage is not present when off or during a fault.
Therefore, the ADP8140 can be safely used in conjunction with
power supplies that produce over 100 V for their output.
POWER CONTROL OPERATION
The ADP8140 controls a power stage with its COMP and
FB_OUT pins. The power stage allows the IC to optimize the
efficiency and protection of the LEDs. The ADP8140 operates
in two power control modes: error amplifier and low gain
buffer. The MODE pin is used to select the power control mode.
Rev. B | Page 12 of 23
Data Sheet
ADP8140
The FB_OUT pin outputs a current, which indicates power
control. A higher FB_OUT sink current indicates that more
power is required to the LEDs. A lower FB_OUT sink current
indicates that less power is required for the LEDs. This
operation makes the FB_OUT ideal for any power control
application that does not normally have an error amplifier. The
two primary applications for this are as follows:
MODE PIN OPERATION
The MODE pin is used to program one of four possible modes
of operation. The condition of the MODE pin affects the DIM
pin input (see the Reducing the LED Current with the DIM Pin
section) and the power control mode (see Power Control Modes
section). The MODE pin state is read at power-up only, when
VIN crosses the UVLO threshold. After this point, the MODE
pin voltage is 0 V. The MODE status cannot change after power-up.
Table 5. Modes of Operation Programmed by the MODE Pin
MODE Connection
GND
30.1 kΩ to GND
52.3 kΩ to GND
REG
DIM Pin Mode
Analog voltage
Analog voltage
PWM signal
PWM signal
Power Control
Error amplifier
Low gain buffer
Low gain buffer
Error amplifier
Depending on the power stage used, an RC network must be
connected to the COMP pin. The COMP pin connects to the
output of the FB_OUT transconductance amplifier. To select
the COMP resistor and capacitor values, a free simulation tool,
ADIsimPE, is available at: www.analog.com/ADIsimPE.
POWER CONTROL MODES
Error Amplifier Power Control
Using this tool, and the included ADP8140 circuit model, the
loop control and stability can be easily simulated and adjusted
for different setups.
In the error amplifier power control mode, the ADP8140
applies the minimum voltage of the four current sinks to the
inverting input of an internal error amplifier. The output of this
error amplifier connects to the FB_OUT inverting buffer.
SINK1
SINK2
SINK3
Controlling an optocoupler on the secondary side of an
isolated power supply
Controlling a PMOS transistor to regulate power in a fixed
output voltage supply.
SINK4
COMP
FB_OUT
VEA(REF)
ID1
ID2
MIN
AND
MAX
MIN
MAX
5.7V
SINK
CONTROL
SHUTDOWN
ID3
CH_OVP
8V/15V
10935-024
ID4
SINK_EN
Figure 22. Error Amplifier Power Control
Rev. B | Page 13 of 23
ADP8140
Data Sheet
Low Gain Buffer Power Control
In the low gain buffer power control mode, the ADP8140
multiplies the minimum voltage of the four current sinks by
GBUFF (3.9 typical; see Table 1) and outputs it to the COMP pin.
This mode allows the ADP8140 to easily control nearly any
switched mode power supply (SMPS) control IC, such as a buck
regulator or boost controller. Common examples are shown in
Figure 32 to Figure 36.
In this mode, the COMP pin is connected to the feedback (FB)
input of an SMPS controller. The FB_OUT pin can be left
floating or connected to GND. Do not tie it to COMP or any
other pin. Connect the FAULT pin to the EN signal of the SMPS
IC. This connection ensures that the power delivery immediately
shuts down in the event of a fault.
Set the value of R1 to be small enough so that the internal
250 kΩ pull-down resistance on the COMP pin does not affect
the total resistance. For example, if R1 = 10 kΩ, VHR = 325 mV,
and FB_REF = 600 mV, then
3.9 0.325
R2 10 kΩ
1 11.1 kΩ
0.6
Next, select R3 to set the maximum voltage applied to the SMPS
FB input.
R3
VREG R1
R1 R2
FBMAX
E
A
A
The values of R1, R2, and R3 program the minimum headroom
voltage on the SINKx pins and set the maximum voltage that
the SMPS FB input receives. A spreadsheet is available at
www.analog.com/ADP8140 to assist in these calculations.
Otherwise, to find the values start with the following equation:
3.9 VHR
R2 R1
1
FB _ REF
where:
FB_REF is the internal error amplifier reference voltage of the
SMPS IC. This is typically 600 mV or 1.2 V. However, it does
vary for different ICs; therefore, consult the data sheet of that IC.
VHR is the minimum headroom voltage that the ADP8140
current sinks need (see Figure 7 to Figure 9). This value varies
based on the maximum sink current that is programmed on the
ISET pin.
where FBMAX is the maximum voltage desired on the SMPS FB
input. Therefore, if FBMAX = 720 mV,
R3
3 V 10 kΩ
0.720
10 kΩ 11.1 k 20.6 kΩ
Ensure that FBMAX is sufficiently higher than the maximum
FB_REF operating point. Some extra margin is beneficial.
DIMMING THE LED CURRENT
The ADP8140 offers multiple methods of dimming. The
dimming input can be either an analog voltage or a PWM
signal. The LED output current can be either scaled (dc
dimming) or pulsed on and off in response to the PWM input
signal. The two dimming pins, DIM and VT, provides different
functions, but both pins can be used for dimming simultaneously,
which provides enormous flexibility in controlling the LED
current.
VREG
SINK1
SINK2
SINK3
SINK4
R3
ID1
MIN
AND
MAX
MIN
600mV
R2
COMP
4×
250kΩ
FB
R1
OPEN-DRAIN
BUFFER
ID2
BUCK OR BOOST IC
SINK
CONTROL
ID4
8V/15V
ADP8140
Figure 23. Low Gain Buffer Power Control
Rev. B | Page 14 of 23
10935-025
ID3
Data Sheet
ADP8140
REDUCING THE LED CURRENT WITH THE DIM PIN
The DIM pin scales the output current when either an analog
voltage or a PWM signal is applied to it. The response of the
ADP8140 to the DIM pin depends on the condition of the
MODE pin.
If the MODE pin is connected to GND or a 30.1 kΩ resistor at
startup, the DIM pin functions as an analog voltage input. As
such, a DIM voltage of 2 V or greater does not impact the output
current. A DIM voltage of 0 V reduces the output current to as
low as 125 μA (see Figure 15). Any DIM voltage between 0 V
and 2 V linearly scales the output current.
MODE
MODE = GND
ANALOG CONTROL
100%
OUTPUT(%)
DIM
SCALE
10935-026
2V
DIM (V)
Figure 24. Reducing the Output Current by Applying an Analog Voltage to
the DIM Pin
If MODE is connected to REG or to a 52.3 kΩ resistor at
startup, a PWM duty cycle applied to the DIM pin is internally
filtered and used to scale the output currents. Set the DIM pin
frequency between 140 Hz and 40 kHz. A lower frequency
PWM signal gives the ADP8140 more information about the
applied duty cycle and leads to better resolution of the duty
cycle, which translates into smaller LED current step sizes on
the current sink digital-to-analog converters (DACs).
current goes to the value dictated by the ISET and DIM pins.
If the PWM input is low, the current becomes the minimum
current as defined in Figure 15. This small current allows the
LEDs to be slightly biased and minimizes the voltage difference
between the off and on states, which greatly reduces the
response time of the power delivery loop.
In this mode, the 7.75 V SINKx clamp is disabled. When the
clamp is disabled, the voltages on the SINKx pins rise as high as
15.1 V (typical) during the LED off time.
If MIN < 2.2 V, the voltage on the VT pin linearly scales the
LED current. VT voltages greater than 2 V (typical) produce
100% of the programmed ISET current. When VT is less than
2 V, the output current is reduced 1% per 20 mV. If the voltage
on the VT pin is below the voltage on the MIN pin, the power
supply to the LEDs is disabled. If the VT pin voltage rises above
the MIN threshold, plus some hysteresis, the power supply is
reenabled. If both the VT pin and the DIM pin are used for
analog dimming, the pin that gives the lower LED current is
used to set the LED current.
To implement thermal protection of the LEDs, the VT pin is
connected to an external negative temperature coefficient
(NTC) resistor. This NTC resistor is typically placed on the LED
heat sink. Selecting the value of the NTC and the resistor in the
network shapes the slope of the VT voltage in response to the
LED temperature. A resistor divider on the MIN pin sets the
level at which the power stage (FB_OUT and COMP) are
disabled.
VREG
VT
NTC
100%
VREG
MODE
MODE = VREG
MIN
SCALE PWM
MIN
2V
VT (V)
SCALE
100%
OUTPUT(%)
Figure 26. Using an External NTC to Implement LED Thermal Protection
100%
DIM DUTY CYCLE (%)
SCALE
10935-027
DIM
10935-028
OUTPUT(%)
Figure 25. Reducing the Average Output Current by Pulse Width Modulating
the Current Sinks with the DIM Pin
When DIM = 0 V, or 0% duty cycle, the minimum output current
is a function of the programmed RSET value. This minimum
value varies between 125 μA and 250 μA, depending on the RSET
value. The typical value as a function of RSET is shown in Figure 15
of the Typical Performance Characteristics section.
DIMMING LEDS WITH THE VT PIN
The VT pin has two modes of operation, depending on the
configuration of the MIN pin.
If MIN is connected to REG at startup, a PWM input to the VT
pin pulses the LED current sinks. If the PWM input is high, the
FAULT PROTECTIONS
To ensure the safety of the LEDs, the ADP8140 IC, and the
power source, the ADP8140 includes a comprehensive array of
detection and protection features.
Power supply overvoltage protection
LED overtemperature protection
LED short-circuit protection
LED open-circuit protection
IC overtemperature protection
Shorted ISET protection
Open ISET and EN protection
These features are summarized in the flowchart shown in
Figure 27.
Rev. B | Page 15 of 23
ADP8140
Data Sheet
DIE TEMP PROTECTION
FAULT DETECTION
NO
SCALE ILED
DOWN
SHUTDOWN
FAULT>1.2V
(10µs NOISE
FILTER)
TURN POWER
STAGE OFF
(LEAVE ALL
SINKS ON)
DIE TEMP
> 150°C
YES
YES
NO
EN = LOW
NO
EN = HIGH
YES
FAULT>1.1V
(10µs NOISE
FILTER)
DIE TEMP
> 135°C
NO
NO
ACTIVE
VT < MIN
(10µs NOISE
YES
NO
NO
FILTER)
YES
MAX(CHx)
> 7.5V?
ISET
PROTECTION
YES
NO
NO
YES
YES
SET
FAULT
LOW
YES
MAX(CHx)
> 15V
YES
NO
REMOVE
SINKx FROM
MIN CIRCUIT
VO_SNS
< 1.15V
YES
SET
FAULT
LOW
REMOVE
SINKx FROM
MIN CIRCUIT
CHANNEL
OVERVOLTAGE
PROTECTION
SET
FAULT
LOW
YES
MAX(CHx)
< 13.8V?
NO
YES
ANY
ACTIVE CHx
< 550mV?
MAX(CHx)
< 4.5V
SET ALL SINKS TO
FULL ISET CURRENT
VOUT OVP
ANY SINK
< 75mV?
MAX(CHx)
> 5.5V?
NO
YES
RSET
< 4.5kΩ
YES
VO_SNS > 1.2V
(10µs NOISE
FILTER)
NO
YES
VT < MIN+
VMIN (HYS)
NO
SET
FAULT
LOW
DIE TEMP
> 130°C
VT PROTECTION
SET
FAULT
LOW
YES
SET ALL SINKS
TO 500mA
CHANNEL
CLAMPS
10935-029
SET
FAULT
LOW
Figure 27. Fault Flowchart
LED OPEN-CIRCUIT AND SHORT-CIRCUIT
PROTECTION
1.15 V (typical), the FB_OUT function resumes its normal
operation and FAULT goes high.
An LED open-circuit fault can result from a bad solder
connection or damaged LED. An open LED string results in the
current sink headroom falling to a very low level. The feedback
loop naturally interprets this as a request for more power. This
can quickly lead to a case where the output voltage is too high.
However, on the ADP8140, any abnormally high output voltage
is detected by the VO_SNS pin and the SINKx pins.
Alternatively, the output voltage may not rise high enough to
trigger the VO_SNS pin, but it may rise high enough to cause
one of the SINKx pins to exceed 5.7 V (typical), or a shorted
LED may cause the SINKx pins to exceed this level. To prevent
excessive power dissipation and damage to the IC, when a
SINKx pin rises above 5.7 V (typical), a channel overvoltage
fault (CH_OVP) is declared. During a CH_OVP fault, any sinks
with a voltage less than 525 mV (typical) are removed from the
FB_OUT path. Then the FB_OUT pull-down NMOS is
released, causing the power stage to shut down. The LED
current sinks are left enabled during this event. When the
SINKx voltage drops to 4.5 V (typical), the FB_OUT function
resumes its normal operation.
E
A
The VO_SNS pin senses the output voltage of the power supply
through an external resistor divider. VO_SNS is then compared
to an internal threshold (1.2 V typical). If the output voltage
rises such that the voltage of the VO_SNS pin is greater than
1.2 V, an output overvoltage fault (VOUT_OVP) is declared.
During a VOUT_OVP fault, any sinks with a voltage less than
80 mV (typical) are removed from the FB_OUT path. Then the
FB_OUT pull-down NMOS is released and FAULT goes low,
causing the power stage to shut down. The LED current sinks
are left enabled during this event. When VO_SNS drops to
E
A
A
A
Continued output overvoltage operation degrades efficiency
and can affect the lifetime of passive components. Therefore,
when an overvoltage condition is detected (either VOUT_OVP
or CH_OVP), then any open LED current sinks are identified
and removed from the feedback loop. But the sinks are always
Rev. B | Page 16 of 23
Data Sheet
ADP8140
left enabled, so that they can regulate the current if the opencircuit or short-circuit LED condition is removed. Bringing EN
or VIN low and then high again restores all sinks to the
feedback loop.
shuts down the power stage with COMP, FB_OUT, and FAULT.
When the temperature drops below 130°C (typical), the
ADP8140 restarts the power stage. If the fault or high power
dissipation persists, the sequence repeats.
VO_SNS can also be used to monitor the input voltage. When
connected to the input voltage through a resistor divider, the
ADP8140 shuts down and disables any power stages if the
supply input voltage rises too high. This shutdown can help to
protect the LEDs and power stage.
USING MULTIPLE ADP8140 ICS
E
A
A
DIE TEMPERATURE PROTECTION
Multiple ADP8140 ICs can be combined in parallel to control
the same supply. This combination is advantageous to control
more than four strings of LEDs or to drive higher currents. For
example, using two ADP8140 ICs, four LED strings can be
driven at 1 A each, or two strings can be driven at 2 A each.
Significant voltage mismatch between LED strings can create
high power dissipation within the ADP8140. If this increase in
power dissipation causes the die temperature on the ADP8140
to rise above 135°C (typical), the IC automatically begins to
reduce the output current on all four sinks. If the die temperature continues to rise and exceeds 150°C (typical), the ADP8140
When using multiple ADP8140 ICs in parallel to control one
power supply, all of the FAULT and EN pins must be connected
together. If any FAULT pin goes low, all ADP8140 ICs respond
to the event. Most applications will work best if the dimming
signals are also connected amongst the ADP8140 ICs, though it
is not required.
E
A
A
E
A
A
COUT
PGND PGND PGND PGND PGND SW
SW
SW
SW
BST
GND
ADP2384
PVIN
VREG
PVIN
FB
PVIN
COMP
PVIN
EN PGOOD RT
SYNC
SS
RT
ADP8140
VIN
VIN
MIN
REG
VT
MODE
DIM
ADP8140
VIN
VIN
REG
DIM
MODE
MIN
VT
DIM
EN
SINK1
EN
SINK1
FAULT
SINK2
FAULT
SINK2
FB_OUT
SINK3
FB_OUT
SINK3
COMP
SINK4
COMP
ISET
VO_SNS
EXPOSED PAD
ISET
DIM
SINK4
VO_SNS
EXPOSED PAD
10935-030
VIN
PGND
FAULT
ENABLE
Figure 28. Multiple ADP8140 ICs Powered from One Supply (Low Gain Buffer Control Shown)
Rev. B | Page 17 of 23
ADP8140
Data Sheet
OPERATING THE ADP8140 FROM HIGHER INPUT
VOLTAGES
The ADP8140 is capable of operating from an input voltage
(VIN) range of 3.0 V to 30 V. However, higher voltages can be
used to power the ADP8140 when an appropriate current
limiting circuit is used.
It is sometimes sufficient to limit the voltage on the VIN pin by
placing a Zener diode on VIN and limiting the current with a
resistor from the input voltage to the VIN pin. This method can
be used if standby power dissipation is not an issue.
Alternatively, if the supply voltage range is small, an additional
Zener diode between the supply and the VIN pin shifts the
voltage at the VIN pin below 30 V. This method adds minimal
power dissipation in both standby and active modes.
However, a more robust voltage limiter uses a Zener diode, an
NPN transistor, and two resistors. This simple circuit, shown in
Figure 29, gives the required operating IQ during normal
operation but also reduces the standby current when the
ADP8140 is disabled.
EFFECT OF LED VF MISMATCH
The ADP8140 always controls the FB_OUT pin to regulate the
output voltage to provide the minimum amount of headroom
voltage required for the current sinks. One of the current sinks
is regulated to VEA(REF). Typically, VEA(REF) is either 350 mV or
450 mV (see VEA(350) and VEA(450) in Table 1). The voltage seen on
the other three SINKx pins varies based on the distribution of
the LED forward voltage, VF. For a given lot of LEDs, the VF and
the change in VF with temperature is relatively consistent. Given
a VF distribution, the maximum voltage that appears on any of
the SINKx pins can be statistically calculated. For example,
consider a mean VF of 3.5 V and a normal distribution with a
standard deviation of 70 mV. A statistical analysis of such a
distribution reveals the maximum voltage that may appear on
any of the SINKx pins, as shown in Figure 30). Note that in
Figure 30, the maximum value is defined as the average plus six
standard deviations (σ) of the distribution.
3.5
SINKx VOLTAGE (V)
VCC
RLIM
VZ
VIN
CIN
ADP8140
Figure 29. VIN Current Limiting Circuit for High Input Voltages
2.0
1.5
1.0
0.5
Select VZ to give a voltage well below the 30 V absolute
maximum of the VIN pin. With this circuit, the VIN pin voltage
is regulated to about VZ − 0.7 V. Select the resistor, RZ, to limit
the current when the ADP8140 is disabled yet still provide
enough current to reverse bias the Zener diode and drive the
NPN transistor when the ADP8140 is active. The current
through RZ is given by
V VZ
I RZ CC
RZ
2.5
0
10935-032
IB
10935-031
RZ
AVERAGE
MAX
3.0
0
5
10
15
20
25
Figure 30. Voltage on SINKx Pins Given a Normal Distribution of VF, Standard
Deviation = 70 mV
The SINKx voltage found on each pin determines the power
that the ADP8140 package must dissipate. Specifically, the
ADP8140 power dissipation can be represented as follows:
PDISS = (VSINK1 + VSINK2 + VSINK3 + VSINK4) × ILED
A value of 100 μA at the minimum expected VCC is generally
sufficient. Even at maximum VCC, this value only contributes a
few milliwatts of power dissipation during standby.
RLIM limits the maximum current during transients. A value of a
few hundred ohms is sufficient. When the ADP8140 is active,
the additional worst case power dissipation from this limit
circuitry is given by
30
NUMBER OF LEDs PER STRING
(2)
A statistical analysis based on the VF distribution of the LED
can be performed to predict the total power dissipation within
the ADP8140. For the same distribution used in Equation 2 and
an LED current of 350 mA, Figure 31 gives the average and
maximum power dissipations. Note that in Figure 31, the
maximum value is defined as the average plus six standard
deviations of the distribution.
ΔPDISS(ACTIVE) = (VCC(MAX) – VZ(MIN) + 0.7 V) × IQ =
(48 V − 24 V + 0.7 V) × 3 mA = 74 mW
Rev. B | Page 18 of 23
Data Sheet
ADP8140
3.0
AVERAGE
MAX
SINKx VOLTAGE (V)
2.5
2.0
1.5
1.0
0
10935-033
0.5
0
5
10
15
20
25
30
ORDERING OPTIONS
NUMBER OF LEDs PER STRING
The ADP8140 is available in two options. The difference
between the options is the VEA(REF) voltage and the number of
sinks that control the COMP and FB_OUT voltage.
Figure 31. Total Power Dissipation (All Four Strings) for a Normal
Distribution of VF, Standard Deviation = 70 mV, ILED = 350 mA
MANAGING THE POWER DISSIPATION OF THE
ADP8140
With the predicted power dissipation known, the next step is to
determine if the ADP8140 package is able to dissipate that
power adequately. Use the following to calculate the maximum
power that the ADP8140 is able to dissipate:
PDISS(MAX) = (TJ − TBOARD)/θJB
= (135 − 105)/12.4 = 2.4 W
See Figure 33 to Figure 36 for examples of the ADP8140 used in
various configurations: with a PMOS regulation stage, as a
secondary side controller, with a boost or buck power stage, or
with one power stage.
ADP8140ACPZ-1-R7
The ADP8140ACPZ-1-R7 has VEA(REF) at 350 mV. Therefore, if
using the device with the PMOS power stage or as a secondary
side controller, each current sink can supply up to 350 mA of
LED current at 350 mV of headroom voltage. However, if using
the device to control an SMPS IC, each current sink can supply
up to 500 mA of LED current.
where:
TJ =135°C, the maximum ADP8140 junction temperature
(before entering thermal foldback).
TBOARD = 105°C, the maximum board temperature.
θJB = 12.4°C/W (see Table 3).
Assume that 100% of the power dissipates through the exposed
pad to the board.
The ability of the ADP8140 package to dissipate heat varies if
the operating conditions are not consistent with the θJB
conditions given in Table 3. Additionally, it is imperative to
follow the layout guidelines given in the Layout Guidelines
section.
LAYOUT GUIDELINES
For optimum performance, follow these layout guidelines:
The ADP8140 is designed for easy layout with single sided
metal core substrates. If FR4 substrate is used, thermal vias
must be used between the LFCSP exposed pad and a large
ground trace on the opposite side of the board.
Place the REG capacitor close to the IC. The location of the
VIN capacitor is not as important.
Place the COMP capacitor(s) and resistor as close to the IC
as possible.
Place the VO_SNS resistors (if used) close to the IC.
If applying an analog dimming voltage to the DIM or VT
pins, placing a bypass capacitor near these pins reduces the
noise on these dimming signals.
The exposed pad of the ADP8140 must be properly
connected to a heat sink. Solder the exposed pad to the
PCB and connect it to a large plane of ground metal with
an array of thermal vias.
The minimum voltage for all four of the current sinks is used to
control the power regulation (COMP and FB_OUT).
ADP8140ACPZ-2-R7
The ADP8140ACPZ-2-R7 has VEA(REF) at 450 mV. Therefore, all
four of the sinks can be driven to 500 mA in any configuration.
Only the minimum voltage from SINK1, SINK2, and SINK3 is
used to control the FB_OUT and COMP pins. Therefore, this is
the preferred device model if only three LED strings are used in
a system. SINK4 can be left floating or connected to GND. Note
that SINK4 is still enabled; if it is connected to an LED string, it
regulates its current to be the same as the other sinks. Therefore,
SINK4 can be combined with another SINKx pin (for example
to drive two strings at 1 A each).
Rev. B | Page 19 of 23
ADP8140
Data Sheet
VCC
NTC
ADP8140
VIN
REG
MODE
ENABLE
FAULT
MIN
VT
DIM
EN
SINK1
FAULT
SINK2
FB_OUT SINK3
COMP
ISET
SINK4
VO_SNS
10935-034
EXPOSED PAD
Figure 32. ADP8140 with a PMOS Regulation Stage
D1
VCC
POWER FACTOR
CORRECTION/
FLYBACK
CONTROLLER
COUT
DRV
M1
CS
RCS
NTC
FB
RN
GND
ADP8140
MIN
VIN
REG
VZS
VT
MODE
ROPTO
AC INPUT
VOLTAGE
DIM
EN
SINK1
FAULT
SINK2
FB_OUT SINK3
COMP
CIN CREG
CC
RSET
SINK4
VO_SNS
EXPOSED PAD
Figure 33. ADP8140 Secondary Side Control Design Example
Rev. B | Page 20 of 23
RO1
RO2
10935-035
ISET
Data Sheet
ADP8140
VIN
AGND
VCC
FB
BST
VIN
COMP
EN
ADP2441
SW
PGND
NTC
PGOOD FREQ SS/TRK
ADP8140
VIN
MIN
REG
VT
MODE
EN
SINK1
FAULT
SINK2
FB_OUT
SINK3
DIM
SINK4
COMP
VO_SNS
ISET
10935-036
nFAULT
ENABLE
DIM
EXPOSED PAD
Figure 34. ADP8140 with a Buck Power Stage
ADP8140
6
VIN
SW 5
VIN
REG
ADP1612
3
7
8
MODE
EN
EN
FB 2
FREQ
SS
COMP 1
GND
MIN
VT
DIM
EN
SINK1
FAULT
SINK2
FB_OUT
SINK3
COMP
ISET
SINK4
VO_SNS
EXPOSED PAD
4
Figure 35. ADP8140 with a Boost Power Stage
Rev. B | Page 21 of 23
DIM
10935-037
5V
ADP8140
Data Sheet
COUT
PGND PGND PGND PGND PGND SW
SW
SW
SW
BST
GND
ADP2384
PVIN
VREG
PVIN
FB
PVIN
COMP
PVIN
EN PGOOD RT
SYNC
SS
RT
ADP8140
VIN
VIN
MIN
REG
VT
MODE
DIM
ADP8140
VIN
VIN
REG
DIM
MODE
MIN
VT
DIM
EN
SINK1
EN
SINK1
FAULT
SINK2
FAULT
SINK2
FB_OUT
SINK3
FB_OUT
SINK3
COMP
SINK4
COMP
ISET
VO_SNS
EXPOSED PAD
ISET
DIM
SINK4
VO_SNS
EXPOSED PAD
10935-038
VIN
PGND
nFAULT
ENABLE
Figure 36. Multiple ADP8140 ICs with One Power Stage
Rev. B | Page 22 of 23
Data Sheet
ADP8140
OUTLINE DIMENSIONS
DETAIL A
(JEDEC 95)
4.10
4.00 SQ
3.90
3.40
3.30
3.20
0.40 BSC
9
PIN 1 INDEX
AREA
16
2.80
2.70
2.60
EXPOSED
PAD
0.50
0.40
0.30
1
8
0.20 MIN
BOTTOM VIE W
TOP VIEW
PIN 1
INDIC ATOR AREA OPTIONS
(SEE DETAIL A)
PKG-003927
SEATING
PLANE
SIDE VIEW
0.05 MAX
0.02 NOM
COPLANARITY
0.08
0.203 REF
0.25
0.20
0.15
FOR PROPER CONNECTION OF
THE EXPOSED PAD, REFER TO
THE PIN CONFIGURATION AND
FUNCTION DESCRIPTIONS
SECTION OF THIS DATA SHEET.
COMPLIANT TO JEDEC STANDARDS MO-229-WGGE.
06-19-2018-B
0.80
0.75
0.70
Figure 37. 16-Lead Lead Frame Chip Scale Package [LFCSP]
4 mm × 4 mm Body and 0.75 mm Package Height
(CP-16-29)
Dimensions shown in millimeters
ORDERING GUIDE
Model1, 2, 3
ADP8140ACPZ-1-R7
ADP8140ACPZ-2-R7
ADP8140EB-EVALZ
ADP8140CP-EVALZ
VEA(REF) (mV)
350
450
Temperature Range
−40°C to +125°C
−40°C to +125°C
Package Description
16-Lead LFCSP, 7” Tape and Reel
16-Lead LFCSP, 7” Tape and Reel
ADP8140 PMOS Evaluation Board
ADP8140EB-EVALZ with the LEDs and Heat Sink
1
Z = RoHS Compliant Part.
ADP8140ACPZ-1-R7: SINK4 function is normal.
3
ADP8140ACPZ-2-R7: SINK4 regulates current but does not control FB_OUT and COMP.
2
©2015–2020 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D10935-9/20(B)
Rev. B | Page 23 of 23
Package Option
CP-16-29
CP-16-29
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