650 kHz/1.3 MHz, 4 A, Step-Up,
PWM, DC-to-DC Switching Converter
Data Sheet
ADP1614
FEATURES
Adjustable and fixed current-limit options
Adjustable up to 4 A
Fixed 3 A
2.5 V to 5.5 V input voltage range
650 kHz or 1.3 MHz fixed frequency option
Adjustable output voltage, up to 20 V
Adjustable soft start
Undervoltage lockout
Thermal shutdown
3 mm × 3 mm, 10-lead LFCSP
Supported by ADIsimPower design tool
APPLICATIONS
TFT LCD bias supplies
Portable applications
Industrial/instrumentation equipment
GENERAL DESCRIPTION
The ADP1614 is a step-up, dc-to-dc switching converter with
an integrated power switch capable of providing an output voltage
as high as 20 V. The ADP1614 is available with a pin-adjustable
current limit that is set via an external resistor with the boost
switching frequency fixed to either 650 kHz or 1.3 MHz.
Alternatively, the ADP1614 is also available with fixed 3 A
current limit and a pin-selectable frequency. With a package
height of 0.8 mm, the ADP1614 is optimal for space constrained
applications, such as portable devices or thin film transistor
(TFT) liquid crystal displays (LCDs).
The ADP1614 operates in current-mode pulse-width modulation
(PWM) with up to 94% efficiency. Adjustable soft start prevents
inrush currents when the part is enabled. The PWM current-mode
architecture allows excellent transient response, easy noise filtering,
and the use of small, cost-saving external inductors and capacitors.
Other key features include undervoltage lockout (UVLO), thermal
shutdown (TSD), and logic controlled enable.
The ADP1614 is available in a Pb-free, 10-lead lead frame chip
scale package (LFCSP).
TYPICAL APPLICATIONS CIRCUITS
ADP1614
ADJUSTABLE
CURRENT
LIMIT
8
3
9
10
6
2
1
VIN
EN
CLRES
SS
SW
7
SW
FB
COMP
ON
OFF
5
GND
4
GND
11
EP
V
OUT
V
IN
L1
C
IN
C
SS
C
OUT
C
COMP
R
COMP
R
CL
R1
R2
D1
10293-001
Figure 1. Step-Up Regulator Configuration for Adjustable Current-Limit Options
ADP1614
FIXED
CURRENT
LIMIT
L1
8
3
9
10
6
2
1
VIN
EN
FREQ
SS
SW
7
SW
FB
COMP
ON
OFF
1.3MHz
650kHz
(DEFAULT)
5
GND
4
GND
11
EP
VOUT
VIN
CIN
CSS COUT
CCOMP
RCOMP
R1
R2
D1
10293-201
Figure 2. Step-Up Regulator Configuration for Fixed Current-Limit Options
Rev. B Document Feedback
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ADP1614 Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Typical Applications Circuits .......................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Absolute Maximum Ratings ............................................................ 5
Thermal Resistance ...................................................................... 5
ESD Caution .................................................................................. 5
Pin Configuration and Function Descriptions ............................. 6
Typical Performance Characteristics ............................................. 7
Theory of Operation ...................................................................... 12
Current-Mode PWM Operation .............................................. 13
Adjustable Current Limit .......................................................... 13
Frequency Selection ................................................................... 13
Soft Start ...................................................................................... 13
Thermal Shutdown (TSD) ........................................................ 13
Undervoltage Lockout (UVLO) ............................................... 13
Shutdown Mode ......................................................................... 13
Applications Information .............................................................. 14
ADIsimPower Design Tool ....................................................... 14
Setting the Output Voltage ........................................................ 14
Inductor Selection ...................................................................... 14
Choosing the Input and Output Capacitors ........................... 15
Diode Selection ........................................................................... 15
Loop Compensation .................................................................. 15
Soft Start Capacitor .................................................................... 16
PCB Layout Guidelines .................................................................. 17
Outline Dimensions ....................................................................... 18
Ordering Guide .......................................................................... 18
REVISION HISTORY
11/14—Rev. A to Rev. B
Changes to Ordering Guide .......................................................... 18
6/13—Rev. 0 to Rev. A
Changes to Features Section, General Description Section, and
Figure 1 .............................................................................................. 1
Added Figure 2; Renumbered Sequentially .................................. 1
Changes to Table 1 ............................................................................ 3
Added FREQ Pin to Table 2 ............................................................ 5
Changes to Pin 9 ............................................................................... 6
Added Figure 26 and Figure 27..................................................... 10
Added Figure 28 to Figure 31 ........................................................ 11
Changes to Theory of Operation Section and Figure 32 ........... 12
Changes to Adjustable Current Limit Section and Frequency
Selection Section ............................................................................. 13
Changes to Figure 35 and Figure 36 Captions ............................ 17
Updated Outline Dimensions ....................................................... 18
Changes to Ordering Guide .......................................................... 18
6/12—Revision 0: Initial Version
Rev. B | Page 2 of 18
Data Sheet ADP1614
SPECIFICATIONS
VIN = 3.6 V, unless otherwise noted. Minimum and maximum values are guaranteed for TJ = −40°C to +125°C. Typical values specified
are at TJ = 25°C. All limits at temperature extremes are guaranteed by correlation and characterization using standard statistical quality
control (SQC), unless otherwise noted.
Table 1.
Parameter Symbol
Test Conditions/Comments Min Typ Max Unit
SUPPLY
Input Voltage VIN 2.5 5.5 V
Quiescent Current
Shutdown IQSHDN VEN = 0 V, VSW = GND 0.25 1.5 µA
Nonswitching State IQ VFB = 1.3 V, VSW = GND, fSW = 1.3 MHz and 650 kHz 700 1100 µA
Switching State1 IQSW fSW = 1.3 MHz, VSW = GND, no load 5.5 7 mA
fSW = 650 kHz, VSW = GND, no load 3 4.5 mA
UNDERVOLTAGE LOCKOUT (UVLO)
Undervoltage Lockout Threshold VIN rising 2.33 2.5 V
VIN falling 2.0 2.20 V
OUTPUT
Output Voltage2 VOUT VIN 20 V
Load Regulation VOUT = 10 V, ILOAD = 1 mA to 1 A 0.005
mV/mA
REFERENCE
Feedback Voltage VFB 1.2250 1.2445
1.2650 V
Line Regulation VIN = 2.5 V to 5.5 V 0.02 0.2 %/V
ERROR AMPLIFIER
Transconductance GMEA ΔI = 4 µA 150 µA/V
Voltage Gain AV 80 dB
FB Pin Bias Current VFB = 1.245 V 1 50 nA
SWITCH (SW)
On Resistance RDSON ISW = 1.0 A 50 100 mΩ
Adjustable Peak Current Limit3 RCL = 154 kΩ, duty cycle = 70% 0.95 1.30 1.65 A
Maximum Adjustable Peak
Current Limit2
RCL = 61.9 kΩ, VIN = 3.6 V, VOUT = 15 V 4 A
Fixed Peak Current Limit3 ADP1614ACPZ-R7 only, duty cycle = 70% 2.50 3.10 3.60 A
SW Pin Leakage Current VSW = 20 V 0.1 10 µA
CLRES VOLTAGE4
ADP1614ACPZ-650-R7 and ADP1614ACPZ-1.3-R7
ICLRES = 5 µA 1.225 1.27 1.315 V
ICLRES = 20 µA 1.18 1.22 1.25 V
OSCILLATOR
Oscillator Frequency fSW ADP1614ACPZ-1.3-R7 and ADP1614ACPZ-R7, VFREQ ≥ 1.6 V 1.1 1.3 1.4 MHz
ADP1614ACPZ-650-R7 and ADP1614ACPZ-R7, VFREQ ≤ 0.3 V 500 650 720 kHz
Maximum Duty Cycle DMAX COMP = open, VFB = 1 V, fSW = 1.3 MHz and 650 kHz 88 92 %
EN/FREQ LOGIC THRESHOLD FREQ pin is ADP1614ACPZ-R7 only
Input Voltage Low VIL VIN = 2.5 V to 5.5 V 0.3 V
Input Voltage High VIH VIN = 2.5 V to 5.5 V 1.6 V
EN Pin Leakage Current IEN VEN = 3.6 V 3.4 7 µA
FREQ Pin Leakage Current VFREQ = 3.6 V, VFB = 1.3 V
0.005 1
µA
SOFT START (SS)
Charging Current ISS VSS = 0 V 3.4 5.5 7 µA
SS Pin Voltage
V
SS
V
FB
= 1.3 V
1.17
1.23
1.29
V
Rev. B | Page 3 of 18
ADP1614 Data Sheet
Parameter Symbol
Test Conditions/Comments Min Typ Max Unit
THERMAL SHUTDOWN
Thermal Shutdown Threshold 150 °C
Thermal Shutdown Hysteresis 20 °C
1 This parameter specifies the average current when the device switches internally with the SW pins (Pin 6 and Pin 7) grounded.
2 Guaranteed by design.
3 Current limit is a function of duty cycle. For the adjustable current limit versions, it is also a function of the resistor on the CLRES pin. See Figure 10 through Figure 13.
4 The CLRES pin cannot be controlled with a current source. An equivalent resistance should be used.
Rev. B | Page 4 of 18
Data Sheet ADP1614
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
VIN, EN, FB, FREQ to GND −0.3 V to +6 V
CLRES to GND −0.3 V to VIN
COMP to GND 1.0 V to 1.6 V
SS to GND −0.3 V to +1.3 V
SW to GND 21 V
Operating Junction Temperature Range −40°C to +125°C
Storage Temperature Range −65°C to +150°C
Soldering Conditions
JEDEC J-STD-020
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.
Absolute maximum ratings apply individually only, not in
combination.
THERMAL RESISTANCE
The junction-to-ambient thermal resistance (θJA) of the package
is specified for the worst-case conditions, that is, a device soldered
in a circuit board for surface-mount packages. The θJA is highly
dependent on the application and board layout. In applications
where high maximum power dissipation exists, attention to
thermal board design is required. The value of θJA may vary,
depending on the printed circuit board (PCB) material, layout,
and environmental conditions.
The boundary conditions for the thermal resistance of the
ADP1614 are modeled under natural convection cooling at
25°C ambient temperature, JESD 51-9, and 1 W power input on a
4-layer board.
Table 3. Thermal Resistance1
Package Type θJA θJC Unit
10-Lead LFCSP 47 7.22 °C/W
1 Thermal numbers per JEDEC standard JESD 51-9.
ESD CAUTION
Rev. B | Page 5 of 18
ADP1614 Data Sheet
Rev. B | Page 6 of 18
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1COMP
2FB
3EN
4GND
5GND
10 SS
9CLRES/FREQ
8VIN
7SW
6SW
ADP1614
TOP VIEW
(Not to Scale)
NOTES
1. THE EXPOSED PAD IS NOT ELECTRICALLY
CONNECTED; CONNECT T HIS P AD TO A GRO UND
PLANE F O R BETT ER HE AT DI STRI BUT ION.
10293-002
Figure 3. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. Mnemonic Description
1 COMP Compensation Input. Connect a series resistor-capacitor network from COMP to GND to compensate the
regulator.
2 FB Output Voltage Feedback Input. Connect a resistive voltage divider from the output voltage to FB to set the
regulator output voltage.
3 EN Enable Input. Drive EN low to shut down the regulator; drive EN high to turn on the regulator.
4, 5 GND Ground.
6, 7 SW Switching Output. Connect the power inductor from the input voltage to SW and connect the external rectifier
from SW to the output voltage to complete the step-up converter.
8 VIN Main Power Supply Input. VIN powers the ADP1614 internal circuitry. Connect VIN to the input source voltage.
Bypass VIN to GND with a 10 μF or greater capacitor as close to the ADP1614 as possible.
9 CLRES/FREQ
Current-Limit Resistor (CLRES). Connect a resistor to GND to set the peak inductor current.
Frequency Setting Input (FREQ). Connect FREQ to GND to program the oscillator to 650 kHz, or connect FREQ to
VIN to program it to 1.3 MHz. Do not leave this pin floating.
10 SS Soft Start. A capacitor connected from SS to GND brings up the output slowly at power-up and reduces inrush
current.
11 EP Exposed Die Attach Pad. The exposed pad is not electrically connected; connect this pad to a ground plane for
better heat distribution.
Data Sheet ADP1614
TYPICAL PERFORMANCE CHARACTERISTICS
110 100 1k 10k
EF FICIENCY ( %)
LOAD CURRENT ( mA)
0
10
20
30
40
60
70
80
90
100
VIN = 3.6V
fSW = 650kHz
RCL = 71.5kΩ
ADP1614ACPZ-650-R7
VOUT = 5V
VOUT = 10V
VOUT = 15V
10293-003
50
Figure 4. Efficiency vs. Load Current, VIN = 3.6 V, fSW = 650 kHz
110 100 1k 10k
EFFI CIENCY ( %)
LO AD CURRE NT (mA)
0
10
20
30
40
50
60
70
80
90
100 VIN = 3.6V
fSW = 1.3MHz
RCL = 71.5kΩ
VOUT = 5V
VOUT = 10V
VOUT = 15V
10293-004
ADP1614ACPZ-1.3-R7
Figure 5. Efficiency vs. Load Current, VIN = 3.6 V, fSW = 1.3 MHz
110 100 1k 10k
EF FICIENCY ( %)
LOAD CURRENT ( mA)
0
10
20
30
40
50
60
70
80
90
100 VIN = 5V
fSW = 650kHz
RCL = 71.5kΩ
VOUT = 10V
VOUT = 15V
VOUT = 20V
10293-005
ADP1614ACPZ-650-R7
Figure 6. Efficiency vs. Load Current, VIN = 5 V, fSW = 650 kHz
110 100 1k 10k
EF FICIENCY ( %)
LOAD CURRENT ( mA)
0
10
20
30
40
50
60
70
80
90
100 VIN = 5V
fSW = 1.3MHz
RCL = 71.5kΩ
VOUT = 10V
VOUT = 15V
VOUT = 20V
10293-006
ADP1614ACPZ-1.3-R7
Figure 7. Efficiency vs. Load Current, VIN = 5 V, fSW = 1.3 MHz
4.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
60 75 90 105 120 135 150
MAXI MUM O UTPUT CURRENT ( A)
RCL (kΩ)
10293-100
VOUT = 5V
VIN = 2.5V
VIN = 3.5V
VIN = 4.5V
ADP1614ACPZ-650-R7
ADP1614ACPZ-1.3-R7
Figure 8. Typical Maximum Continuous Output Current vs. RCL, VOUT = 5 V
1.4
0
0.2
0.4
0.6
0.8
1.0
1.2
60 75 90 105 120 135 150
MAXI MUM O UTPUT CURRENT ( A)
RCL (kΩ)
10293-101
VOUT = 15V
VIN = 2.5V
VIN = 3.5V
VIN = 4.5V
VIN = 5.5V
ADP1614ACPZ-650-R7
ADP1614ACPZ-1.3-R7
Figure 9. Typical Maximum Continuous Output Current vs. RCL, VOUT = 15 V
Rev. B | Page 7 of 18
ADP1614 Data Sheet
4.0
1.0
1.5
2.0
2.5
3.0
3.5
60 75 90 105 120 135 150
CURRENT LI M IT ( A)
RCL (kΩ)
10293-104
VOUT = 5V
VIN = 2.5V
VIN = 3.5V
VIN = 4.5V ADP1614ACPZ-650-R7
ADP1614ACPZ-1.3-R7
Figure 10. Peak Current Limit of Switch vs. RCL, VOUT = 5 V
3.90
3.85
3.80
3.75
3.70
3.65
3.602.5 3.0 3.5 4.0 4.5
CURRENT LI M IT ( A)
INPUT VOLTAGE (V)
10293-102
VOUT = 5V
RCL = 71.5kΩ
TA = –40° C
TA = +25°C
TA = +85°C
ADP1614ACPZ-650-R7
ADP1614ACPZ-1.3-R7
Figure 11. Peak Current Limit of Switch vs. VIN over Temperature, VOUT = 5 V
4.0
3.5
3.0
2.5
2.0
1.5
1.060 75 90 105 120 135 150
CURRENT LI M IT ( A)
RCL (kΩ)
10293-105
VOUT = 15V
VIN = 2.5V
VIN = 3.5V
VIN = 4.5V
VIN = 5.5V
ADP1614ACPZ-650-R7
ADP1614ACPZ-1.3-R7
Figure 12. Peak Current Limit of Switch vs. RCL, VOUT = 15 V
3.60
3.15
3.20
3.25
3.30
3.35
3.40
3.45
3.50
3.55
2.5 3.0 3.5 4.0 5.5
4.0
4.5
CURRENT LI M IT ( A)
INPUT VOLTAGE (V)
10293-103
TA = +85°C
TA = –40° C
TA = +25°C
VOUT = 15V
RCL = 71.5kΩ
ADP1614ACPZ-650-R7
ADP1614ACPZ-1.3-R7
Figure 13. Peak Current Limit of Switch vs. VIN over Temperature, VOUT = 15 V
2.5 5.55.04.54.03.53.0
SWITCH ON RESISTANCE (mΩ)
INPUT VOLTAGE (V)
30
40
50
60
70
80 ISW = 1A
TA = +125°C
TA = +25°C
TA = –40° C
10293-008
Figure 14. Switch On Resistance vs. Input Voltage
2.5 5.55.04.54.03.53.0
MAXIMUM DUTY CYCLE (%)
INPUT VOLTAGE (V)
TA = +25°C TA = –40° C
TA = +125°C
91.0
91.5
92.0
92.5
93.0
93.5
94.0
94.5
10293-015
Figure 15. Maximum Duty Cycle vs. Input Voltage
Rev. B | Page 8 of 18
Data Sheet ADP1614
Rev. B | Page 9 of 18
2.5 5.55.04.54.03.53.0
NONSWITCHING QUIESCENT CURRENT (µA)
INPUT VOLTAGE (V)
T
A
= +125°C
T
A
= +25°C
T
A
= –40°C
580
600
620
640
660
680
700
720
740
760
780
10293-009
Figure 16. Nonswitching Quiescent Current vs. Input Voltage
2.5 5.55.04.54.03.53.0
SWITCHING QUIESCENT CURRENT (mA)
INPUT VOLTAGE (V)
T
A
= +125°C
T
A
= +25°C T
A
= –40°C
2.0
4.5
4.0
3.5
3.0
2.5
f
SW
= 650kHz
10293-011
Figure 17. Switching Quiescent Current vs. Input Voltage, fSW = 650 kHz
2.5 5.55.04.54.03.53.0
SWITCHING QUIESCENT CURRENT (mA)
INPUT VOLTAGE (V)
T
A
= +25°C T
A
= –40°C
3
9
8
7
6
5
4
f
SW
= 1.3MHz
T
A
= +125°C
10293-012
Figure 18. Switching Quiescent Current vs. Input Voltage, fSW = 1.3 MHz
EN PIN CURRENT (µA)
EN PIN VOLTAGE (V)
T
A
= +25°C
T
A
= –40°C
T
A
= +125°C
0
1
2
3
4
5
6
7
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
10293-016
Figure 19. EN Pin Current vs. EN Pin Voltage
SS PIN CURRENT (µA)
TEMPERATURE (°C)
4.8
5.0
5.2
5.4
5.6
5.8
6.0
–40 –10 20 50 80 110
V
IN
= 5.5V
V
IN
= 3.6V
V
IN
= 2.5V
10293-017
Figure 20. SS Pin Current vs. Temperature
10293-106
TIME (4ms/DIV)
1
2
3
4
V
IN
= 3.6V
V
OUT
= 15V
I
LOAD
= 60Ω
C
SS
= 68nF
f
SW
= 1.3MHz
OUTPUT VOLTAGE (5V/DIV)
INDUCTOR CURRENT (500mA/DIV)
SWITCH VOLTAGE (10V/DIV)
EN PIN VOLTAGE (5V/DIV)
Figure 21. Startup, CSS = 68 nF
ADP1614 Data Sheet
Rev. B | Page 10 of 18
10293-020
TIME (200µs/DIV)
1
3
LOAD CURRENT (50mA/DIV)
OUTPUT VOLTAGE (100mV/DIV)
AC-COUPLED
V
IN
= 3.6V
V
OUT
= 5V
f
SW
= 650kHz
L = 4.7µH
Figure 22. 50 mA to 150 mA Load Transient,
VIN = 3.6 V, VOUT = 5 V, fSW = 650 kHz
10293-021
TIME (200µs/DIV)
1
3
LOAD CURRENT (50mA/DIV)
OUTPUT VOLTAGE (100mV/DIV)
AC-COUPLED
V
IN
= 3.6V
V
OUT
= 5V
f
SW
= 1.3MHz
L = 4.7µH
Figure 23. 50 mA to 150 mA Load Transient,
VIN = 3.6 V, VOUT = 5 V, fSW = 1.3 MHz
10293-022
TIME (200µs/DIV)
1
3
LOAD CURRENT (50mA/DIV)
OUTPUT VOLTAGE (100mV/DIV)
AC-COUPLED
V
IN
= 5V
V
OUT
= 15V
f
SW
= 650kHz
L = 15µH
Figure 24. 50 mA to 150 mA Load Transient,
VIN = 5 V, VOUT = 15 V, fSW = 650 kHz
10293-023
TIME (200µs/DIV)
1
3
LOAD CURRENT (50mA/DIV)
OUTPUT VOLTAGE (200mV/DIV)
AC-COUPLED
V
IN
= 5V
V
OUT
= 15V
f
SW
= 1.3MHz
L = 10µH
Figure 25. 50 mA to 150 mA Load Transient,
VIN = 5 V, VOUT = 15 V, fSW = 1.3 MHz
0
10
20
30
40
50
60
70
80
90
100
1m 10m 100m 1 10
EFFICIENCY (%)
LOAD CURRENT (A)
V
OUT
= 8V
V
OUT
= 12V
V
IN
=5V
f
SW
=650kHz
ADP1614ACPZ-R7
10293-126
Figure 26. Efficiency vs. Load Current, VIN = 5 V, fSW = 650 kHz
0
10
20
30
40
50
60
70
80
90
100
1m 10m 100m 1 10
EFFICIENCY (%)
LOAD CURRENT (A)
V
OUT
= 8V
V
OUT
= 12V
V
IN
=5V
f
SW
=1.3MHz
ADP1614ACPZ-R7
10293-127
Figure 27. Efficiency vs. Load Current, VIN = 5 V, fSW = 1.3 MHz
Data Sheet ADP1614
0.3
0.5
0.7
0.9
1.1
1.3
1.5
1.7
2.5 3.0 3.5 4.0 4.5 5.0 5.5
MAXI MUM O UTPUT CURRENT ( A)
INPUT VOLTAGE (V)
ADP1614ACPZ-R7
V
OUT
= 8V
V
OUT
= 12V
10293-128
Figure 28. Typical Maximum Continuous Output Current vs. VIN
2.80
2.85
2.90
2.95
3.00
3.05
3.10
3.15
3.20
3.25
3.30
2.5 3.0 3.5 4.0 4.5 5.0 5.5
CURRENT LIM IT ( A)
INPUT VOLTAGE (V)
T
A
= –40° C
T
A
= +25°C
T
A
= +85°C
V
OUT
= 12V
ADP1614ACPZ-R7
10293-129
Figure 29. Peak Current Limit of Switch vs. VIN over Temperature, VOUT = 12 V
580
590
600
610
620
630
640
650
660
2.5 3.0 3.5 4.0 4.5 5.0 5.5
SW ITCHING FREQ UE NCY ( kHz )
INPUT VOLTAGE (V)
f
SW
= 650kHz
T
A
= –40° C
T
A
= +25°C
T
A
= +125°C
10293-130
Figure 30. Frequency vs. Input Voltage, fSW = 650 kHz
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
f
SW = 1.3MHz
TA = –40° C
TA = +25°C
TA = +125°C
10293-131
1.16
1.18
1.20
1.22
1.24
1.26
1.28
1.30
SW ITCHING FREQ UE NCY (MHz)
Figure 31. Frequency vs. Input Voltage, fSW = 1.3 MHz
Rev. B | Page 11 of 18
ADP1614 Data Sheet
THEORY OF OPERATION
The ADP1614 current-mode, step-up switching converter
boosts a 2.5 V to 5.5 V input voltage to an output voltage as
high as 20 V. The internal switch allows a high output current,
and the 650 kHz/1.3 MHz switching frequency allows the use of
tiny external components. The switch current is monitored on a
pulse-by-pulse basis to limit the current to the value set by the
RCL resistor on the CLRES pin on the adjustable current-limit
version or to 3 A typical on the fixed current-limit version.
SW
PWM
COMPARATOR
UVLO
COMPARATOR
TSD
COMPARATOR
OSCILLATOR
S
RQ
D
COMPARATOR
D
REF
+
+
VIN
VIN
CURRENT
SENSING
FREQ
DRIVER
BAND GAP
N1
BG
RESET
NOTES
1. THE PORT IONS IN T HE DAS HE D BOXES DISP LAY THE T WO P OSSIBL E FUNCT I ONAL IT IES OF P IN 9 ON THE ADP 1614.
1.1MΩ
AGND
V
IN
UVLO
REF
T
SENSE
T
REF
ERROR
AMPLIFIER
V
BG
2
1
5.5µA
V
SS
R
COMP
C
COMP
COMP
SS
FB
C
SS
R1
R2
R
CL
C
IN
V
OUT
8
L1
D1
AV
OUT
C
OUT
6
SW
7
39 5
GND
4
GND
11
EP
AGND
ENCLRES
ADP1614
ADP1614ACPZ-R7
5.5µA
9
10
V
IN
ON
OFF
1.3MHz
650kHz
SOFT
START
10293-024
ADP1614ACPZ-650-R7
AND
ADP1614ACPZ-1.3-R7
Figure 32. Block Diagram with Step-Up Regulator Application Circuit
Rev. B | Page 12 of 18
Data Sheet ADP1614
CURRENT-MODE PWM OPERATION
The ADP1614 utilizes a current-mode PWM control scheme to
regulate the output voltage over all load conditions. The output
voltage is monitored at FB through a resistive voltage divider. The
voltage at FB is compared with the internal 1.245 V reference by
the internal transconductance error amplifier to create an error
voltage at COMP. The current of the switch is internally measured
and added to the stabilizing ramp. The resulting sum is compared
with the error voltage at COMP to control the PWM modulator.
This current-mode regulation system allows fast transient response
while maintaining a stable output voltage. By selecting the proper
resistor-capacitor network from COMP to GND, the regulator
response is optimized for a wide range of input voltages, output
voltages, and load conditions.
ADJUSTABLE CURRENT LIMIT
A key feature of the ADP1614ACPZ-650-R7 and
ADP1614ACPZ-1.3-R7 is a pin-adjustable peak current limit of
up to 4 A (see Figure 10 to Figure 13 and Figure 33). This adjustable
current limit allows the other external components to be selected
specifically for the application. The current limit is set via an
external resistor connected from Pin 9 (CLRES) to ground. For
the ADP1614ACPZ-R7, the current limit is fixed at 3 A.
60 1501351201059075
CURRENT LIM IT ( A)
RCL (kΩ)
1.0
4.0
3.5
3.0
2.5
2.0
1.5
VIN = 3.5V
10293-007
VOUT = 15V
VOUT = 5V
Figure 33. Peak Current Limit of Switch vs. RCL
FREQUENCY SELECTION
The adjustable current-limit versions of the ADP1614 are
internally programmed to operate at either 650 kHz or 1.3 MHz.
Operation of the ADP1614 at 650 kHz (ADP1614ACPZ-650-R7)
optimizes the efficiency of the device, whereas operation of the
ADP1614 at 1.3 MHz (ADP1614ACPZ-1.3-R7) enables the
device to be used with smaller external components. For the
fixed current-limit version (ADP1614ACP-R7), the frequency is
pin selectable via the FREQ Pin (Pin 9). Connect FREQ to
GND for 650 kHz operation or connect FREQ to VIN for
1.3 MHz operation. Do not leave the FREQ pin floating.
SOFT START
To prevent input inrush current to the converter when the part
is enabled, connect a capacitor from SS to GND to set the soft
start period. After the ADP1614 is turned on, SS sources 5 µA
(typical) to the soft start capacitor (CSS) until it reaches 1.23 V at
startup. As the soft start capacitor charges, it limits the peak current
allowed by the part. By slowly charging the soft start capacitor,
the input current ramps slowly to prevent it from overshooting
excessively at startup. When the ADP1614 is disabled, the SS
pin is internally shorted to GND to discharge the soft start
capacitor.
THERMAL SHUTDOWN (TSD)
The ADP1614 includes TSD protection. If the die temperature
exceeds 150°C (typical), TSD turns off the NMOS power device,
significantly reducing power dissipation in the device and
preventing output voltage regulation. The NMOS power device
remains off until the die temperature is reduced to 130°C (typical).
The soft start capacitor is discharged during TSD to ensure low
output voltage overshoot and inrush currents when regulation
resumes.
UNDERVOLTAGE LOCKOUT (UVLO)
If the input voltage is below the UVLO threshold, the ADP1614
automatically turns off the power switch and places the part
into a low power consumption mode. This prevents potentially
erratic operation at low input voltages and prevents the power
device from turning on when the control circuitry cannot
operate it. The UVLO levels have ~100 mV of hysteresis to
ensure glitch-free startup.
SHUTDOWN MODE
The EN pin turns the ADP1614 regulator on or off. Drive EN
low to shut down the regulator and reduce the input current to
0.25 µA (typical). Drive EN high to turn on the regulator.
When the converter is in shutdown mode (EN ≤ 0.3 V), there is a
dc path from the input to the output through the inductor and
output rectifier. This causes the output voltage to remain slightly
below the input voltage by the forward voltage of the rectifier,
preventing the output voltage from dropping to ground when the
regulator is shut down.
Regardless of the state of the EN pin, when a voltage is applied to
the VIN pin, a large current spike occurs due to the nonisolated
path through the inductor and diode between VIN and VOUT. The
high current is a result of the output capacitor charging. The
peak value is dependent on the inductor, output capacitor, and
any load active on the output of the regulator.
Rev. B | Page 13 of 18
ADP1614 Data Sheet
APPLICATIONS INFORMATION
ADIsimPOWER DESIGN TOOL
The ADP1614 is supported by the ADIsimPower™ design toolset.
ADIsimPower is a collection of tools that produce complete
power designs that are optimized for a specific design goal. The
tools enable the user to generate a full schematic and bill of
materials and to calculate performance in minutes. ADIsimPower
can optimize designs for cost, area, efficiency, and parts count
while taking into consideration the operating conditions and
limitations of the IC and the external components. For more
information about the ADIsimPower design tools, visit
www.analog.com/ADIsimPower. The toolset is available from
this website, and users can request an unpopulated board.
SETTING THE OUTPUT VOLTAGE
The ADP1614 features an adjustable output voltage range of VIN
to 20 V. The output voltage is set by the resistor voltage divider,
R1 and R2 (see Figure 32), from the output voltage (VOUT) to the
1.245 V feedback input at FB. Use the following equation to
determine the output voltage:
VOUT = 1.245 × (1 + R1/R2) (1)
Choose R1 based on the following equation:
−
×=
245.1
245.1
OUT
V
R2R1
(2)
INDUCTOR SELECTION
The inductor is an essential part of the step-up switching
converter. It stores energy during the on time of the power
switch and transfers that energy to the output through the
output rectifier during the off time. To balance the trade-offs
between small inductor current ripple and efficiency, inductance
values in the range of 4.7 µH to 22 µH are recommended. In
general, lower inductance values have higher saturation current
and lower series resistance for a given physical size. However,
lower inductance values result in higher peak current, which
can lead to reduced efficiency and greater input and/or output
ripple and noise. A peak-to-peak inductor ripple current close
to 30% of the maximum dc input current typically yields an
optimal compromise.
For determining the inductor ripple current in continuous
operation, the input (VIN) and output (VOUT) voltages determine
the switch duty cycle (D) as follows:
OUT
IN
OUT
V
VV
D−
=
(3)
The duty cycle and switching frequency (fSW) can be used to
determine the on time:
SW
ON
f
D
t=
(4)
The inductor ripple current (∆IL) in steady state is calculated by
L
tV
ION
IN
L
×
=∆
(5)
Solve for the inductance value (L) as follows:
L
ON
IN
I
tV
L∆
×
=
(6)
Ensure that the peak inductor current (the maximum input
current plus half the inductor ripple current) is below the rated
saturation current of the inductor. Likewise, make sure that the
maximum rated rms current of the inductor is greater than the
maximum dc input current to the regulator.
For continuous current-mode (CCM) duty cycles greater than
50% that occur with input voltages less than one-half the output
voltage, slope compensation is required to maintain stability of
the current-mode regulator. For stable current-mode operation,
ensure that the selected inductance is equal to or greater than
the minimum calculated inductance, LMIN, for the application
parameters in the following equation:
SW
INOUT
MIN
fVV
LL ×
×−
=> 8)2(
(7)
Inductors smaller than the 4.7 µH to 22 µH recommended
range can be used as long as Equation 7 is satisfied for the given
application. For input/output combinations that approach the
90% maximum duty cycle, doubling the inductor is recommended
to ensure stable operation. Table 5 suggests a series of inductors
for use with the ADP1614.
Table 5. Suggested Inductors
Manufacturer Part Series
Coilcraft XAL40xx, XAL50xx, XAL6060, DO3316P
TOKO Inc.
FDV06xx, DG6045C, FDSD0630, DEM8045C,
FDVE1040
Würth Elektronik WE-HCI, WE-TPC, WE-PD, WE-PD2, WE -PDF
Vishay Dale IHLP-2020, IHLP-2525, IHLP-3232, IHLP-4040
TDK Components SPM6530, VLP8040, VLF10040, VLF10045
Taiyo Yuden NRS8030, NRS8040
Rev. B | Page 14 of 18
Data Sheet ADP1614
CHOOSING THE INPUT AND OUTPUT CAPACITORS
The ADP1614 requires input and output bypass capacitors to
supply transient currents while maintaining constant input and
output voltages. Use low equivalent series resistance (ESR)
capacitors of 10 µF or greater to prevent noise at the ADP1614
input. Place the capacitor between VIN and GND, as close as
possible to the ADP1614. Ceramic capacitors are preferable
because of their low ESR characteristics. Alternatively, use a
high value, medium ESR capacitor in parallel with a 0.1 µF low
ESR capacitor, placed as close as possible to the ADP1614.
The output capacitor maintains the output voltage and supplies
current to the load while the ADP1614 switch is on. The value
and characteristics of the output capacitor greatly affect the
output voltage ripple and stability of the regulator. A low ESR
ceramic dielectric capacitor is preferable. The output voltage
ripple (∆VOUT) is calculated as follows:
OUT
ONOUT
OUT
C
OUT
CtI
C
Q
V×
==∆
(8)
where:
QC is the charge removed from the capacitor.
COUT is the output capacitance.
IOUT is the output load current.
tON is the on time of the switch.
The on time of the switch is determined as follows:
SW
ON f
D
t=
(9)
The input (VIN) and output (VOUT) voltages determine the
switch duty cycle (D) as follows:
OUT
IN
OUT
V
VV
D−
=
(10)
Choose the output capacitor based on the following equation:
OUTOUTSW
INOUTOUT
OUT VVf VVI
C∆××
−×
≥)(
(11)
Multilayer ceramic capacitors are recommended for this
application.
DIODE SELECTION
The output rectifier conducts the inductor current to the output
capacitor and load while the switch is off. For high efficiency,
minimize the forward voltage drop of the diode. For this reason,
using Schottky rectifiers is recommended. However, for high
voltage, high temperature applications, where the Schottky
rectifier reverse leakage current becomes significant and can
degrade efficiency, use an ultrafast junction diode.
Many diode manufacturers derate the current capability of the
diode as a function of the duty cycle. Verify that the output
diode is rated to handle the average output load current with
the minimum duty cycle. The minimum duty cycle in CCM of
the ADP1614 is
OUT
MAXIN
OUT
MIN
V
VV
D
)
(
−
=
(12)
where VIN(MAX) is the maximum input voltage.
The following are suggested Schottky diode manufacturers:
• ON Semiconductor
• Diodes, Inc.
• Toshib a
• ROHM Semiconductor
LOOP COMPENSATION
The ADP1614 uses external components to compensate the
regulator loop, allowing optimization of the loop dynamics for a
given application.
The step-up converter produces an undesirable right-half plane
zero in the regulation feedback loop. This requires compensating
the regulator such that the crossover frequency occurs well below
the frequency of the right-half plane zero. The right-half plane
zero is determined by the following equation:
L
R
V
V
RHPF LOAD
OUT
IN
Z×π
×
=2
)(
2
(13)
where:
FZ(RHP) is the right-half plane zero.
RLOAD is the equivalent load resistance or the output voltage
divided by the load current.
To stabilize the regulator, ensure that the regulator crossover
frequency is less than or equal to one-fifth of the right-half
plane zero.
The regulator loop gain is
OUTCSCOMPOUTMEA
OUT
IN
OUT
FB
VL
ZGZRG
V
V
V
V
A×××××=
(14)
where:
AVL is the loop gain.
VFB is the feedback regulation voltage, 1.245 V.
VOUT is the regulated output voltage.
VIN is the input voltage.
GMEA is the error amplifier transconductance gain.
ROUT = 67 MΩ.
ZCOMP is the impedance of the series RC network from COMP
to GND.
GCS is the current sense transconductance gain (the inductor
current divided by the voltage at COMP), which is internally
set by the ADP1614.
ZOUT is the impedance of the load in parallel with the output
capacitor.
Rev. B | Page 15 of 18
ADP1614 Data Sheet
To determine the crossover frequency, it is important to note that
at the crossover frequency the compensation impedance (ZCOMP)
is dominated by a resistor, and the output impedance (ZOUT) is
dominated by the impedance of an output capacitor. Therefore,
when solving for the crossover frequency, the equation (by
definition of the crossover frequency) is simplified to
1
2
1=
××
π
××
×××=
OUT
C
CS
COMPMEA
OUT
IN
OUT
FB
VL
C
f
G
RG
V
V
V
V
A
(15)
where:
RCOMP is the compensation resistor.
fC is the crossover frequency.
Solve for RCOMP as follows:
CSMEA
INFB
OUTOUT
C
COMP GGVV
VCf
R×××
×××π
=
2
)(2
(16)
where:
VFB = 1.245 V.
GMEA = 150 µA/V.
GCS = 7 A/V.
Therefore,
IN
OUTOUTC
COMP
VVCf
R
2
)(4806 ×××
=
(17)
After the compensation resistor is known, set the zero formed
by the compensation capacitor and resistor to one-fourth of the
crossover frequency, or
COMPC
COMP
Rf
C××π
=2
(18)
where CCOMP is the compensation capacitor.
R
COMP
C
COMP
C2
1
COMP
g
m
ERROR
AMPLIFIER
2
FB
V
BG
10293-026
Figure 34. Compensation Components
Capacitor C2 is chosen to cancel the zero introduced by the ESR
of the output capacitor.
Solve for C2 as follows:
COMP
OUT
R
CESR
C2 ×
=
(19)
If a low ESR, ceramic output capacitor is used for COUT, C2 is
optional. For optimal transient performance, RCOMP and CCOMP
might need to be adjusted by observing the load transient response
of the ADP1614. For most applications, the compensation
resistor should be within the range of 1 kΩ to 100 kΩ, and the
compensation capacitor should be within the range of 100 pF to
10 nF.
SOFT START CAPACITOR
Upon startup (EN ≥ 1.6 V) or fault recovery, the voltage at SS
ramps up slowly by charging the soft start capacitor (CSS) with
an internal 5.5 µA current source (ISS). As the soft start capacitor
charges, it limits the peak current allowed by the part to prevent
excessive overshoot at startup. Use the following equation to
determine the necessary value of the soft start capacitor (CSS)
for a specific overshoot and start-up time when the part is at the
current limit with maximum load:
SS
SSSS V
t
IC ∆
=
(20)
where:
ISS = 5.5 μA (typical).
Δt is the start-up time at the current limit.
VSS = 1.23 V (typical).
If the applied load does not place the part at the current limit,
the value of CSS can be reduced. A 68 nF soft start capacitor
results in negligible input current overshoot at startup and,
therefore, is suitable for most applications. If an unusually large
output capacitor is used, a longer soft start period is required to
prevent input inrush current.
However, if fast startup is required, the soft start capacitor can
be reduced or removed, which allows the ADP1614 to start
quickly but with greater peak switch current.
Rev. B | Page 16 of 18
Data Sheet ADP1614
PCB LAYOUT GUIDELINES
For high efficiency, good regulation, and stability, a well designed
PCB layout is required.
Use the following guidelines when designing PCBs (see Figure 32
for a block diagram and Figure 3 for a pin configuration).
• Keep the low ESR input capacitor (CIN), which is labeled as
C4 in Figure 35, close to VIN and GND. This minimizes
noise injected into the part from board parasitic inductance.
• Keep the high current path from CIN through the L1 inductor
to SW and GND as short as possible.
• Keep the high current path from VIN through the inductor
(L1), the rectifier (D1), and the output capacitor (COUT),
which is labeled as C7 in Figure 35, as short as possible.
• Keep high current traces as short and as wide as possible.
• Place the feedback resistors as close to FB as possible to
prevent noise pickup. Connect the ground of the feedback
network directly to an AGND plane that makes a Kelvin
connection to the GND pin.
• Place the compensation components as close as possible to
C OM P. C on n e c t the ground of the compensation network
directly to an AGND plane that makes a Kelvin connection
to the GND pin.
• Connect the soft start capacitor (CSS), which is labeled as
C1 in Figure 35, as close as possible to the device. Connect
the ground of the soft start capacitor to an AGND plane
that makes a Kelvin connection to the GND pin.
• Connect the current-limit set resistor (RCL), which is labeled as
R4 in Figure 35, as close as possible to the device. Connect
the ground of the CL resistor to an AGND plane that makes a
Kelvin connection to the GND pin.
• The PCB must be properly designed to conduct the heat
away from the package. This is achieved by adding thermal
vias to the PCB, which provide a thermal path to the inner
or bottom layers. Thermal vias should be placed on the PCB
underneath the exposed pad of the LFCSP and in the GND
plane around the ADP1614 package to improve thermal
performance of the package.
Avoid routing high impedance traces from the compensation
and feedback resistors near any node connected to SW or near
the inductor to prevent radiated noise injection.
10293-027
Figure 35. ADP1614 Recommended Top Layer Layout for the Adjustable
Current-Limit Boost Application
10293-028
Figure 36. ADP1614 Recommended Bottom Layer Layout for the Adjustable
Current-Limit Boost Application
Rev. B | Page 17 of 18
ADP1614 Data Sheet
OUTLINE DIMENSIONS
2.48
2.38
2.23
0.50
0.40
0.30
10
1
6
5
0.30
0.25
0.20
PIN 1 INDEX
AREA
SEATING
PLANE
0.80
0.75
0.70
1.74
1.64
1.49
0.20 REF
0.05 M AX
0.02 NO M
0.50 BSC
EXPOSED
PAD
3.10
3.00 SQ
2.90
PIN 1
INDICATOR
(R 0. 15)
FOR PRO P E R CONNECTION O F
THE EXPOSED PAD, REFER TO
THE PIN CO NFI GURATIO N AND
FUNCTION DES CRIPT IO NS
SECTION OF THIS DATA SHEET.
COPLANARITY
0.08
02-05-2013-C
TOP VIEW BOTTOM VIEW
0.20 M IN
Figure 37. 10-Lead Lead Frame Chip Scale Package [LFCSP_WD]
3 mm × 3 mm Body, Very Very Thin, Dual Lead
(CP-10-9)
Dimensions shown in millimeters
ORDERING GUIDE
Model1
Temperature
Range
Switching
Frequency Current Limit Package Description
Package
Option Branding
ADP1614ACPZ-1.3-R7 −40°C to +125°C 1.3 MHz Adjustable up to 4 A 10-Lead LFCSP_WD CP-10-9 LM4
ADP1614ACPZ-650-R7 −40°C to +125°C 650 kHz Adjustable up to 4 A 10-Lead LFCSP_WD CP-10-9 LM5
ADP1614ACPZ-R7 −40°C to +125°C Pin selectable Fixed 3 A 10-Lead LFCSP_WD CP-10-9 LNG
ADP1614-1.3-EVALZ
1.3 MHz
Adjustable up to 4 A
Evaluation Board, 15 V Output
Voltage Configuration
ADP1614-650-EVALZ 650 kHz Adjustable up to 4 A Evaluation Board, 5 V Output
Voltage Configuration
1 Z = RoHS Compliant Part.
©2012–2014 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D10293-0-11/14(B)
Rev. B | Page 18 of 18
