2 A, Low VIN, Low Dropout
Linear Regulator
Data Sheet
ADP1740/ADP1741
FEATURES
Maximum output current: 2 A
Input voltage range: 1.6 V to 3.6 V
Low shutdown current: 2 µA
Low dropout voltage: 160 mV at 2 A load
Initial accuracy: ±1%
Accuracy over line, load, and temperature: ±2%
7 fixed output voltage options with soft start:
0.75 V to 2.5 V (ADP1740)
Adjustable output voltage options with soft start:
0.75 V to 3.3 V (ADP1741)
High PSRR
65 dB at 1 kHz
65 dB at 10 kHz
54 dB at 100 kHz
23 μV rms at 0.75 V output
Stable with small 4.7 µF ceramic output capacitor
Excellent load and line transient response
Current-limit and thermal overload protection
Power-good indicator
Logic-controlled enable
Reverse current protection
APPLICATIONS
Server computers
Memory components
Telecommunications equipment
Network equipment
DSP/FPGA/microprocessor supplies
Instrumentation equipment/data acquisition systems
TYPICAL APPLICATION CIRCUITS
TOP VIEW
(No t t o Scal e)
ADP1740
1
2
3
4
VIN
VIN
100kΩ
4.7µF 4.7µF
VIN = 1.8V VOUT = 1.5V
VIN
EN
12
11
10
9
VOUT
VOUT
VOUT
SENSE
5678
PG GND SS NC
PG
16 15 14 13
VIN VIN VOUT VOUT
10nF
07081-001
Figure 1. ADP1740 with Fixed Output Voltage, 1.5 V
TOP VIEW
(Not t o Scal e)
ADP1741
1
2
3
4
VIN
VIN
100kΩ
4.7µF 4.7µF
VIN = 1.8V VOUT = 0.5V ( 1 + R1/R2)
VIN
EN
12
11
10
9
VOUT
VOUT
VOUT
ADJ
5678
PG GND SS NC
PG
16 15 14 13
VIN VIN VOUT VOUT
10nF
R2
R1
07081-002
Figure 2. ADP1741 with Adjustable Output Voltage, 0.75 V to 3.3 V
GENERAL DESCRIPTION
The ADP1740/ADP1741 are low dropout (LDO) CMOS linear
regulators that operate from 1.6 V to 3.6 V and provide up to 2 A
of output current. These low VIN/VOUT LDOs are ideal for regu-
lation of nanometer FPGA geometries operating from 2.5 V down
to 1.8 V I/O rails, and for powering core voltages down to 0.75 V.
Using an advanced, proprietary architecture, the ADP1740/
ADP1741 provide high power supply rejection ratio (PSRR) and
low noise, and achieve excellent line and load transient response
with only a small 4.7 µF ceramic output capacitor.
The ADP1740 is available in seven fixed output voltage options.
The ADP1741 is an adjustable version that allows output
voltages ranging from 0.75 V to 3.3 V via an external divider.
The ADP1740/ADP1741 allow an external soft start capacitor
to be connected to program the startup. A digital power-good
output allows power system monitors to check the health of the
output voltage.
The ADP1740/ADP1741 are available in a 16-lead, 4 mm ×
4 mm LFCSP, making them not only very compact solutions,
but also providing excellent thermal performance for applica-
tions that require up to 2 A of output current in a small, low
profile footprint.
Rev. H Document Feedback
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ADP1740/ADP1741 Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Typical Application Circuits ............................................................ 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Input and Output Capacitor, Recommended Specifications .. 4
Absolute Maximum Ratings ............................................................ 5
Thermal Data ................................................................................ 5
Thermal Resistance ...................................................................... 5
ESD Caution .................................................................................. 5
Pin Configurations and Function Descriptions ........................... 6
Typical Performance Characteristics ............................................. 7
Theory of Operation ...................................................................... 11
Soft Start Function ..................................................................... 11
Adjustable Output Voltage (ADP1741) ................................... 12
Enable Feature ............................................................................ 12
Power-Good Feature .................................................................. 12
Reverse Current Protection Feature ........................................ 13
Applications Information .............................................................. 14
Capacitor Selection .................................................................... 14
Undervoltage Lockout ............................................................... 15
Current-Limit and Thermal Overload Protection ................. 15
Thermal Considerations ............................................................ 15
PCB Layout Considerations ...................................................... 17
Outline Dimensions ....................................................................... 19
Ordering Guide .......................................................................... 19
REVISION HISTORY
1/15—Rev. G to Rev. H
Changes to Ordering Guide .......................................................... 19
4/14—Rev. F to Rev. G
Changes to Figure 1 and Figure 2 ................................................... 1
Changes to Figure 3 and Figure 4 ................................................... 6
Updated Outline Dimensions ....................................................... 19
Changes to Ordering Guide .......................................................... 19
8/13—Rev. E to Rev. F
Changes to Ordering Guide .......................................................... 19
6/13—Rev. D to Rev. E
Changed Adjustable Output Voltage Option with Soft Start
(ADP1755) from 0.75 V to 3.0 V to 0.75 V to 3.3 V
(Throughout) .................................................................................... 1
Updated Outline Dimensions ....................................................... 19
12/12—Rev. C to Rev. D
Added Junction Temperature of 150°C, Table 3 ........................... 5
Changes to Ordering Guide .......................................................... 19
9/12—Rev. B to Rev. C
Changes to Table 3 ............................................................................ 5
Changes to Ordering Guide .......................................................... 19
2/10—Rev. A to Rev. B
Changes to Table 4 ............................................................................ 5
Changes to Ordering Guide .......................................................... 19
4/09—Rev. 0 to Rev. A
Changes to Table 3 ............................................................................ 5
10/08—Revision 0: Initial Version
Rev. H | Page 2 of 20
Data Sheet ADP1740/ADP1741
SPECIFICATIONS
VIN = (VOUT + 0.4 V) or 1.6 V (whichever is greater), IOUT = 100 mA, CIN = COUT = 4.7 µF, TA = 25°C, unless otherwise noted.
Table 1.
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
INPUT VOLTAGE RANGE VIN TJ = −40°C to +125°C 1.6 3.6 V
OPERATING SUPPLY CURRENT1 IGND IOUT = 500 µA 90 µA
IOUT = 100 mA 400 µA
I
OUT
= 100 mA, T
J
= −40°C to +125°C
800
µA
IOUT = 2 A 1.5 mA
IOUT = 2 A, TJ = −40°C to +125°C 1.8 mA
SHUTDOWN CURRENT IGND-SD EN = GND, VIN = 3.6 V 2 6 µA
EN = GND, VIN = 1.6 V, TJ = −40°C to +85°C 30 µA
EN = GND, VIN = 3.6 V, TJ = −40°C to +85°C 100 µA
OUTPUT VOLTAGE ACCURACY
Fixed Output Voltage Accuracy
(ADP1740)
VOUT IOUT = 100 mA −1 +1 %
IOUT = 10 mA to 2 A −1.5 +1.5 %
10 mA < IOUT < 2 A, TJ = −40°C to +125°C −2 +2 %
Adjustable Output Voltage
Accuracy (ADP1741)2
VADJ IOUT = 100 mA 0.495 0.5 0.505 V
IOUT = 10 mA to 2 A 0.492 0.508 V
10 mA < IOUT < 2 A, TJ = −40°C to +125°C 0.490 0.510 V
LINE REGULATION ∆VOUT/∆VIN VIN = (VOUT + 0.4 V) to 3.6 V, TJ = −40°C to +125°C −0.3 +0.3 %/V
LOAD REGULATION3 ∆VOUT/∆IOUT IOUT = 10 mA to 2 A, TJ = −40°C to +125°C 0.5 %/A
DROPOUT VOLTAGE4 VDROPOUT IOUT = 100 mA, VOUT ≥ 1.8 V 10 mV
IOUT = 100 mA, VOUT ≥ 1.8 V, TJ = −40°C to +125°C 18 mV
IOUT = 2 A, VOUT ≥ 1.8 V 160 mV
IOUT = 2 A, VOUT ≥ 1.8 V, TJ = −40°C to +125°C 280 mV
START-UP TIME5 tSTART-UP CSS = 0 nF, IOUT = 10 mA 200 µs
CSS = 10 nF, IOUT = 10 mA 5.2 ms
CURRENT-LIMIT THRESHOLD6 ILIMIT 2.4 3 5 A
THERMAL SHUTDOWN
Thermal Shutdown Threshold
TS
SD
T
J
rising
150
°
C
Thermal Shutdown Hysteresis TSSD-HYS 15 °C
PG OUTPUT LOGIC LEVEL
PG Output Logic High PGHIGH 1.6 V ≤ VIN ≤ 3.6 V, IOH < 1 µA 1.0 V
PG Output Logic Low PGLOW 1.6 V ≤ VIN ≤ 3.6 V, IOL < 2 mA 0.4 V
PG Output Delay from EN
Transition, Low to High
1.6 V ≤ VIN ≤ 3.6 V, CSS = 10 nF 5.5 ms
PG OUTPUT THRESHOLD
Output Voltage Falling PGFALL 1.6 V ≤ VIN ≤ 3.6 V −10 %
Output Voltage Rising PGRISE 1.6 V ≤ VIN ≤ 3.6 V −6.5 %
EN INPUT
EN Input Logic High VIH 1.6 V ≤ VIN ≤ 3.6 V 1.2 V
EN Input Logic Low
V
IL
1.6 V ≤ V
IN
≤ 3.6 V
0.4
V
EN Input Leakage Current VI-LEAKAGE EN = VIN or GND 0.1 1 µA
UNDERVOLTAGE LOCKOUT UVLO
Input Voltage Rising UVLORISE 1.58 V
Input Voltage Falling UVLOFALL 1.25 V
Hysteresis UVLOHYS 100 mV
SOFT START CURRENT
I
SS
1.6 V ≤ V
IN
≤ 3.6 V
0.6
0.9
1.2
µA
ADJ INPUT BIAS CURRENT
(ADP1741)
ADJI-BIAS 1.6 V ≤ VIN ≤ 3.6 V, TJ = −40°C to +125°C 10 150 nA
Rev. H | Page 3 of 20
ADP1740/ADP1741 Data Sheet
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
SENSE INPUT BIAS CURRENT
(ADP1740)
SNSI-BIAS 1.6 V ≤ VIN ≤ 3.6 V 10 µA
OUTPUT NOISE OUTNOISE 10 Hz to 100 kHz, VOUT = 0.75 V 23 µV rms
10 Hz to 100 kHz, VOUT = 2.5 V 65 µV rms
POWER SUPPLY REJECTION RATIO
PSRR
V
IN
= V
OUT
+ 1 V, I
OUT
= 10 mA
1 kHz, VOUT = 0.75 V 65 dB
1 kHz, VOUT = 2.5 V 56 dB
10 kHz, VOUT = 0.75 V 65 dB
10 kHz, VOUT = 2.5 V 56 dB
100 kHz, VOUT = 0.75 V 54 dB
100 kHz, VOUT = 2.5 V 51 dB
1 Minimum output load current is 500 μA.
2 Accuracy when VOUT is connected directly to ADJ. When VOUT voltage is set by external feedback resistors, absolute accuracy in adjust mode depends on the tolerances
of the resistors used.
3 Based on an endpoint calculation using 10 mA and 2 A loads. See Figure 6 for typical load regulation performance.
4 Dropout voltage is defined as the input to output voltage differential when the input voltage is set to the nominal output voltage. This applies only to output voltages
above 1.6 V.
5 Start-up time is defined as the time between the rising edge of EN to VOUT being at 95% of its nominal value.
6 Current-limit threshold is defined as the current at which the output voltage drops to 90% of the specified typical value. For example, the current limit for a 1.0 V
output voltage is defined as the current that causes the output voltage to drop to 90% of 1.0 V, or 0.9 V.
INPUT AND OUTPUT CAPACITOR, RECOMMENDED SPECIFICATIONS
Table 2.
Parameter
Symbol
Test Conditions/Comments
Min
Typ
Max
Unit
MINIMUM INPUT AND OUTPUT CAPACITANCE1 CMIN TA = –40°C to +125°C 3.3 µF
CAPACITOR ESR RESR TA = –40°C to +125°C 0.001 0.1 Ω
1 The minimum input and output capacitance should be greater than 3.3 µF over the full range of operating conditions. The full range of operating conditions in the
application must be considered during capacitor selection to ensure that the minimum capacitance specification is met. X7R and X5R type capacitors are recommended;
Y5V and Z5U capacitors are not recommended for use with this LDO.
Rev. H | Page 4 of 20
Data Sheet ADP1740/ADP1741
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
VIN to GND −0.3 V to +4.0 V
VOUT to GND
−0.3 V to V
IN
EN to GND −0.3 V to VIN
SS to GND −0.3 V to VIN
PG to GND −0.3 V to +4.0 V
SENSE/ADJ to GND −0.3 V to VIN
Storage Temperature Range −65°C to +150°C
Junction Temperature Range −40°C to +125°C
Junction Temperature 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.
THERMAL DATA
Absolute maximum ratings apply only individually, not in
combination. The ADP1740/ADP1741 may be damaged when
junction temperature limits are exceeded. Monitoring ambient
temperature does not guarantee that the junction temperature is
within the specified temperature limits. In applications with
high power dissipation and poor PCB thermal resistance, the
maximum ambient temperature may need to be derated. In
applications with moderate power dissipation and low PCB
thermal resistance, the maximum ambient temperature can
exceed the maximum limit as long as the junction temperature
is within specification limits.
The junction temperature (TJ) of the device is dependent on the
ambient temperature (TA), the power dissipation of the device
(PD), and the junction-to-ambient thermal resistance of the
package (θJA). TJ is calculated using the following formula:
TJ = TA + (PD × θJA)
The junction-to-ambient thermal resistance (θJA) of the package
is based on modeling and calculation using a 4-layer board. The
junction-to-ambient thermal resistance is highly dependent on
the application and board layout. In applications where high
maximum power dissipation exists, close attention to thermal
board design is required. The value of θJA may vary, depending
on PCB material, layout, and environmental conditions. The
specified values of θJA are based on a 4-layer, 4 in × 3 in circuit
board. Refer to JEDEC JESD51-7 for detailed information about
board construction. For more information, see the AN-772
Application Note, A Design and Manufacturing Guide for the
Lead Frame Chip Scale Package (LFCSP), at www.analog.com.
ΨJB is the junction-to-board thermal characterization parameter
with units of °C/W. ΨJB of the package is based on modeling and
calculation using a 4-layer board. The JEDEC JESD51-12
document, Guidelines for Reporting and Using Electronic Package
Thermal Information, states that thermal characterization
parameters are not the same as thermal resistances. ΨJB measures
the component power flowing through multiple thermal paths
rather than through a single path, as in thermal resistance (θJB).
Therefore, ΨJB thermal paths include convection from the top of
the package, as well as radiation from the package, factors that
make ΨJB more useful in real-world applications. Maximum
junction temperature (TJ) is calculated from the board temper-
ature (TB) and the power dissipation (PD) using the following
formula:
TJ = TB + (PD × ΨJB)
Refer to the JEDEC JESD51-8 and JESD51-12 documents for
more detailed information about ΨJB.
THERMAL RESISTANCE
θJA and ΨJB are specified for the worst-case conditions, that is, a
device soldered in a circuit board for surface-mount packages.
Table 4. Thermal Resistance
Package Type θJA ΨJB Unit
16-Lead LFCSP with Exposed Pad 42 25.5 °C/W
ESD CAUTION
Rev. H | Page 5 of 20
ADP1740/ADP1741 Data Sheet
Rev. H | Page 6 of 20
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
NOTES
1. NC = NO CONNECT.
2. THE EXPO SED PAD ON THE BOT T OM OF T HE L F CSP ENHANCES
THERMAL PERFORMANCE AND IS ELECTRICALLY CONNECTED TO GND
INSIDE THE PACKAG E. IT I S RECOMMENDED THAT THE EXPOSED PAD
BE CO NNE CTED T O T HE GRO UND PL AN E O N T HE BOARD.
07081-003
12
11
10
1
3
49
2
6
5
7
8
16
15
14
13
VIN
VIN
VIN
EN
VOUT
VOU
T
VOU
T
VIN
VIN
VOUT
VOUT
SENSE
PG
GND
SS
NC
ADP1740
TOP VIEW
NOTES
1. NC = NO CON NECT.
2
. T HE EXPO SED PAD ON THE BOTT O M OF THE LF CSP ENHANCES
THE RMAL P ERFORMANCE AND I S EL ECTRICAL LY CONNECTED TO GND
INS IDE THE P ACKA GE. IT I S RECO MMEND ED THA T THE EXPOSED PAD
BE CO NN ECTE D TO THE GROUN D P LANE ON T HE BOARD.
07081-004
12
11
10
1
3
49
2
6
5
7
8
16
15
14
13
VIN
VIN
VIN
EN
VOUT
VOU
T
VOU
T
VIN
VIN
VOUT
VOUT
ADJ
PG
GND
SS
NC
ADP1741
TOP VIEW
Figure 3. ADP1740 Pin Configuration Figure 4. ADP1741 Pin Configuration
Table 5. Pin Function Descriptions
Pin No.
Mnemonic Description
ADP1740 ADP1741
1, 2, 3, 15, 16 1, 2, 3, 15, 16 VIN Regulator Input Supply. Bypass VIN to GND with a 4.7 μF or greater capacitor. Note that all
five VIN pins must be connected to the source supply.
4 4 EN
Enable Input. Drive EN high to turn on the regulator; drive it low to turn off the regulator. For
automatic startup, connect EN to VIN.
5 5 PG
Power-Good Output. This open-drain output requires an external pull-up resistor to VIN. If
the part is in shutdown mode, current-limit mode, or thermal shutdown, or if it falls below
90% of the nominal output voltage, the PG pin immediately transitions low.
6 6 GND Ground.
7 7 SS Soft Start Pin. A capacitor connected to this pin determines the soft start time.
8 8 NC Not Connected. No internal connection.
9 SENSE
Sense Input. This pin measures the actual output voltage at the load and feeds it to the error
amplifier. Connect the SENSE pin as close to the load as possible to minimize the effect of IR
drop between the regulator output and the load.
9 ADJ Adjust Pin. A resistor divider from VOUT to ADJ sets the output voltage.
10, 11, 12,
13, 14
10, 11, 12,
13, 14
VOUT Regulated Output Voltage. Bypass VOUT to GND with a 4.7 μF or greater capacitor. Note that
all five VOUT pins must be connected to the load.
EP EP Exposed
pad
The exposed pad on the bottom of the LFCSP enhances thermal performance and is
electrically connected to GND inside the package. It is recommended that the exposed pad
be connected to the ground plane on the board.
Data Sheet ADP1740/ADP1741
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 1.9 V, V OUT = 1.5 V, IOUT = 100 mA, CIN = COUT = 4.7 µF, TA = 25°C, unless otherwise noted.
1.520
1.515
1.510
1.505
1.500
1.495
1.490
1.485
1.480 –40 –5 25 85 125
OUTPUT VOLTAGE (V)
JUNCTI ON T E M P E RATURE (°C)
07081-005
LO AD = 10mA
LO AD = 100mA
LO AD = 400mA
LO AD = 800mA
LO AD = 1.2A
LO AD = 2A
Figure 5. Output Voltage vs. Junction Temperature
1.520
1.515
1.505
1.495
1.510
1.500
1.490
1.485
1.48010 100 1k 10k
OUTPUT VOLTAGE (V)
LO AD CURRE NT (mA)
07081-006
Figure 6. Output Voltage vs. Load Current
1.8
3.63.43.23.0
2.82.62.42.22.0 INPUT VOLTAGE (V)
LO AD = 10mA
LO AD = 100mA
LO AD = 400mA
LO AD = 800mA
LO AD = 1.2A
LO AD = 2A
07081-007
1.520
1.515
1.510
1.505
1.500
1.495
1.490
1.485
1.480
OUTPUT VOLTAGE (V)
Figure 7. Output Voltage vs. Input Voltage
1600
0
200
400
600
800
1000
1200
1400
–40 –5 25 85 125
GRO UND CURRE NT (µ A)
JUNCTI ON T E M P E RATURE (°C)
LO AD = 10mA
LO AD = 100mA
LO AD = 400mA
LO AD = 800mA
LO AD = 1.2A
LO AD = 2A
07081-008
Figure 8. Ground Current vs. Junction Temperature
1600
1400
1200
1000
800
600
400
200
010 100 1k 10k
GRO UND CURRE NT (µ A)
LO AD CURRE NT (mA)
07081-009
Figure 9. Ground Current vs. Load Current
1600
1400
1200
1000
800
600
400
200
01.8 3.63.43.23.02.82.62.42.22.0
GRO UND CURRE NT (µ A)
INPUT VOLTAGE (V)
LO AD = 10mA
LO AD = 100mA
LO AD = 400mA
LO AD = 800mA
LO AD = 1.2A
LO AD = 2A
07081-010
Figure 10. Ground Current vs. Input Voltage
Rev. H | Page 7 of 20
ADP1740/ADP1741 Data Sheet
100
90
70
80
60
50
40
30
20
10
0
–40 856035
10
–15
SHUTDOW N CURRE NT (µA)
TEMPERATURE (°C)
1.9V
2.0V
2.4V
2.6V
3.0V
3.6V
07081-011
Figure 11. Shutdown Current vs. Temperature at Various Input Voltages
0.25
0.20
0.15
0.10
0.05
0110 100 1k 10k
DROPOUT VOLTAGE (V)
LO AD CURRE NT (mA)
07081-012
1.6V
2.5V
Figure 12. Dropout Voltage vs. Load Current, VOUT = 1.6 V, 2.5 V
2.50
2.35
2.45
2.40
2.30
2.25
2.20
2.15
2.102.3 2.5 2.72.4 2.6 2.8
OUTPUT VOLTAGE (V)
INPUT VOLTAGE (V)
LO AD = 10mA
LO AD = 100mA
LO AD = 400mA
LO AD = 800mA
LO AD = 1.2A
LO AD = 2A
07081-013
Figure 13. Output Voltage vs. Input Voltage (in Dropout), VOUT = 2.5 V
4500
2500
4000
3500
3000
2000
1500
1000
500
02.3 2.5 2.7
2.4 2.6 2.8
GRO UND CURRE NT (µ A)
INPUT VOLTAGE (V)
LO AD = 10mA
LO AD = 100mA
LO AD = 400mA
LO AD = 800mA
LO AD = 1.2A
LO AD = 2A
07081-014
Figure 14. Ground Current vs. Input Voltage (in Dropout), VOUT = 2.5 V
CH1 1.0 A Ω
BW
CH2 50mV
BW
M10µs A CH1 380mA
1
2
T 10.40%
T
07081-015
I
LOAD
1mA TO 2A LO AD S TEP, 2.5A/µs, 1A/DIV
V
OUT
50mV/DIV
V
IN
= 3.6V
V
OUT
= 1.5V
Figure 15. Load Transient Response, CIN = 4.7 µF, COUT = 4.7 µF
CH1 1.0 A Ω
BW
CH2 50mV
BW
M10µs A CH1 880mA
1
2
T 10.20%
T
07081-016
I
LOAD
1mA TO 2A LO AD S TEP, 2.5A/µs, 1A/DIV
V
OUT
50mV/DIV
V
IN
= 3.6V
V
OUT
= 1.5V
Figure 16. Load Transient Response, CIN = 22 µF, COUT = 22 µF
Rev. H | Page 8 of 20
Data Sheet ADP1740/ADP1741
1
2
T
07081-017
CH1 500mV
BW
CH2 5mV
BW
M10µs A CH4 800mV
T 9.40%
V
IN
3V TO 3.5V INPUT VOLTAGE STEP, 2V/µs
V
OUT
5mV/DIV
V
OUT
= 1.5V
C
IN
= C
OUT
= 4.7µF
Figure 17. Line Transient Response, Load Current = 2 A
70
0
10
20
30
40
50
60
0.0001 0.001 0.01 0.1 110
NOI S E ( µV rms)
LO AD CURRE NT (A)
07081-018
0.75V
1.5V
2.5V
Figure 18. Noise vs. Load Current and Output Voltage
10
1
0.1
0.0110 100 1k 10k 100k
NOISE SPECTRAL DENSITY (µV/ Hz)
FREQUENCY ( Hz )
07081-019
0.75V
1.5V
2.5V
Figure 19. Noise Spectral Density vs. Output Voltage, ILOAD = 10 mA
0
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
10 100 1k 10k 100k 1M 10M
PSRR (dB)
FREQUENCY ( Hz )
LO AD = 2A
LO AD = 1.2A
LO AD = 800mA
LO AD = 400mA
LO AD = 100mA
LO AD = 10mA
07081-020
Figure 20. Power Supply Rejection Ratio vs. Frequency,
VOUT = 0.75 V, VIN = 1.75 V
10 100 1k 10k 100k 1M 10M
PSRR (dB)
FREQUENCY ( Hz )
07081-021
0
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10 LO AD = 2A
LO AD = 1.2A
LO AD = 800mA
LO AD = 400mA
LO AD = 100mA
LO AD = 10mA
Figure 21. Power Supply Rejection Ratio vs. Frequency,
VOUT = 1.5 V, VIN = 2.5 V
0
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
10 100 1k 10k 100k 1M 10M
PSRR (dB)
FREQUENCY ( Hz )
07081-022
LOAD = 2A
LOAD = 1.2A
LOAD =800mA
LOAD =400mA
LOAD =100mA
LOAD =10mA
Figure 22. Power Supply Rejection Ratio vs. Frequency,
VOUT = 2.5 V, VIN = 3.5 V
Rev. H | Page 9 of 20
ADP1740/ADP1741 Data Sheet
0
–80
–70
–60
–50
–40
–30
–20
–10
10 100 1k 10k 100k 1M 10M
PSRR (dB)
FREQUENCY ( Hz )
1.5V/2A
2.5V/10mA
0.75V/2A
2.5V/2A
0.75V/10mA
1.5V/10mA
07081-048
Figure 23. Power Supply Rejection Ratio vs. Frequency and Output Voltage
Rev. H | Page 10 of 20
Data Sheet ADP1740/ADP1741
THEORY OF OPERATION
The ADP1740/ADP1741 are low dropout linear regulators
that use an advanced, proprietary architecture to provide high
power supply rejection ratio (PSRR) and excellent line and load
transient response with only a small 4.7 µF ceramic output capac-
itor. Both devices operate from a 1.6 V to 3.6 V input rail and
provide up to 2 A of output current. Supply current in shutdown
mode is typically 2 µA.
UVLO
VOUTVIN
SENSE
SS
SHORT-CIRCUIT
AND THERMAL
PROTECTION
R1
0.5V
REF R2
SHUTDOWN
EN
PG
GND
ADP1740
REVERSE POLARITY
PROTECTION
PG
DETECT 0.9µA
07081-023
Figure 24. ADP1740 Internal Block Diagram
UVLO
VOUT
VIN
ADJ
SS
SHORT-CIRCUIT
AND THERMAL
PROTECTION
0.5V
REF
SHUTDOWN
EN
PG
GND
ADP1741
REVERSE POLARITY
PROTECTION
PG
DETECT 0.9µA
07081-024
Figure 25. ADP1741 Internal Block Diagram
Internally, the ADP1740/ADP1741 consist of a reference,
an error amplifier, a feedback voltage divider, and a PMOS
pass transistor. Output current is delivered via the PMOS pass
transistor, which is controlled by the error amplifier. The error
amplifier compares the reference voltage with the feedback
voltage from the output and amplifies the difference. If the feed-
back voltage is lower than the reference voltage, the gate of the
PMOS device is pulled lower, allowing more current to pass
and increasing the output voltage. If the feedback voltage is
higher than the reference voltage, the gate of the PMOS device
is pulled higher, allowing less current to pass and decreasing the
output voltage.
The ADP1740 is available in seven fixed output voltage options
from 0.75 V to 2.5 V. The ADP1740 allows for connection of an
external soft start capacitor, which controls the output voltage
ramp during startup. The ADP1741 is an adjustable version with
an output voltage that can be set to a value from 0.75 V to 3.3 V
by an external voltage divider. Both devices are controlled by an
enable pin (EN).
SOFT START FUNCTION
For applications that require a controlled startup, the ADP1740/
ADP1741 provide a programmable soft start function. The
programmable soft start is useful for reducing inrush current
upon startup and for providing voltage sequencing. To implement
soft start, connect a small ceramic capacitor from SS to GND.
Upon startup, a 0.9 µA current source charges this capacitor.
The ADP1740/ADP1741 start-up output voltage is limited by
the voltage at SS, providing a smooth ramp-up to the nominal
output voltage. The soft start time is calculated as follows:
tSS = VREF × (CSS/ISS) (1)
where:
tSS is the soft start period.
VREF is the 0.5 V reference voltage.
CSS is the soft start capacitance from SS to GND.
ISS is the current sourced from SS (0.9 µA).
When the ADP1740/ADP1741 are disabled (using the EN pin),
the soft start capacitor is discharged to GND through an
internal 100 Ω resistor.
2.50
0
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
02 4 6 8 10
VOLTAGE (V)
TIME (ms)
EN
1nF
4.7nF
10nF
07081-025
Figure 26. VOUT Ramp-Up with External Soft Start Capacitor
Rev. H | Page 11 of 20
ADP1740/ADP1741 Data Sheet
CH1 2.0V
BW
CH2 500mV
BW
M40µs A CH1 920mV
1
2
T 9.8%
T
07081-026
EN
V
OUT
500mV/DIV V
OUT
= 1.5V
C
IN
= C
OUT
= 4.7µF
Figure 27. VOUT Ramp-Up with Internal Soft Start
ADJUSTABLE OUTPUT VOLTAGE (ADP1741)
The output voltage of the ADP1741 can be set over a 0.75 V to
3.3 V range. The output voltage is set by connecting a resistive
voltage divider from VOUT to ADJ. The output voltage is calcu-
lated using the following equation:
VOUT = 0.5 V × (1 + R1/R2) (2)
where:
R1 is the resistor from VOUT to ADJ.
R2 is the resistor from ADJ to GND.
The maximum bias current into ADJ is 150 nA, so to achieve less
than 0.5% error due to the bias current, use values less than
60 kΩ for R2.
ENABLE FEATURE
The ADP1740/ADP1741 use the EN pin to enable and disable
the VOUT pins under normal operating conditions. As shown
in Figure 28, when a rising voltage on EN crosses the active
threshold, VOUT turns on. When a falling voltage on EN
crosses the inactive threshold, VOUT turns off.
2
CH1 500mV
BW
CH2 500mV
BW
M2.0ms A CH1 1.05V
1
T 29.6%
T
07081-027
EN
V
OUT
500mV/DIV V
OUT
= 1.5V
C
IN
= C
OUT
= 4.7µF
Figure 28. Typical EN Pin Operation
As shown in Figure 28, the EN pin has hysteresis built in. This
hysteresis prevents on/off oscillations that can occur due to
noise on the EN pin as it passes through the threshold points.
The EN pin active/inactive thresholds are derived from the VIN
voltage. Therefore, these thresholds vary with changing input
voltage. Figure 29 shows typical EN active/inactive thresholds
when the input voltage varies from 1.6 V to 3.6 V.
1.1
0.5
0.6
0.7
0.8
0.9
1.0
1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6
EN THRE S HOL D ( V )
INPUT VOLTAGE (V)
EN ACTIVE
EN INACTI V E
07081-028
Figure 29. Typical EN Pin Thresholds vs. Input Voltage
POWER-GOOD FEATURE
The ADP1740/ADP1741 provide a power-good pin, PG, to
indicate the status of the output. This open-drain output
requires an external pull-up resistor to VIN. If the part is in
shutdown mode, current-limit mode, or thermal shutdown, or
if it falls below 90% of the nominal output voltage, the power-
good pin (PG) immediately transitions low. During soft start,
the rising threshold of the power-good signal is 93.5% of the
nominal output voltage.
The open-drain output is held low when the ADP1740/ADP1741
have sufficient input voltage to turn on the internal PG transistor.
An optional soft start delay can be detected. The PG transistor
is terminated via a pull-up resistor to VOUT or VIN.
Power-good accuracy is 93.5% of the nominal regulator output
voltage when this voltage is rising, with a 90% trip point when
this voltage is falling. Regulator input voltage brownouts or
glitches trigger power no-good if VOUT falls below 90%.
A normal power-down triggers power no-good when VOUT
drops below 90%.
Rev. H | Page 12 of 20
Data Sheet ADP1740/ADP1741
2
2
CH1 1.0V
BW
CH3 1.0V
BW
CH2 500mV
BW
M40.0µs A CH3 900mV
1
T 50.40%
T
07081-029
V
IN
1V/DIV
V
OUT
500mV/DIV
PG
1V/DIV
V
OUT
= 1.5V
C
IN
= C
OUT
= 4.7µF
Figure 30. Typical PG Behavior vs. VOUT, VIN Rising (VOUT = 1.5 V)
2
2
CH1 1.0V
BW
CH3 1.0V
BW
CH2 500mV
BW
M40.0µs A CH3 900mV
1
T 50.40%
T
07081-030
V
IN
1V/DIV
V
OUT
500mV/DIV
PG
1V/DIV
V
OUT
= 1.5V
C
IN
= C
OUT
= 4.7µF
Figure 31. Typical PG Behavior vs. VOUT, VIN Falling (VOUT = 1.5 V)
REVERSE CURRENT PROTECTION FEATURE
The ADP1740/ADP1741 have additional circuitry to protect
against reverse current flow from VOUT to VIN. For a typical
LDO with a PMOS pass device, there is an intrinsic body diode
between VIN and VOUT. When VIN is greater than VOUT, this
diode is reverse-biased. If VOUT is greater than VIN, the intrinsic
diode becomes forward-biased and conducts current from
VOUT to VIN, potentially causing destructive power dissipation.
The reverse current protection circuitry detects when VOUT is
greater than VIN and reverses the direction of the intrinsic diode
connection, reverse-biasing the diode. The gate of the PMOS
pass device is also connected to VOUT, keeping the device off.
Figure 32 shows a plot of the reverse current vs. the VOUT to VIN
differential.
4000
3500
3000
2500
2000
1500
1000
500
000.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3 3.6
REVERS E CURRE NT (µ A)
V
OUT
– V
IN
(V)
07081-132
Figure 32. Reverse Current vs. VOUT − VIN
Rev. H | Page 13 of 20
ADP1740/ADP1741 Data Sheet
APPLICATIONS INFORMATION
CAPACITOR SELECTION
Output Capacitor
The ADP1740/ADP1741 are designed for operation with small,
space-saving ceramic capacitors, but they function with most
commonly used capacitors as long as care is taken with regard
to the effective series resistance (ESR) value. The ESR of the
output capacitor affects the stability of the LDO control loop. A
minimum of 3.3 µF capacitance with an ESR of 100 mΩ or less is
recommended to ensure the stability of the ADP1740/ADP1741.
Transient response to changes in load current is also affected by
output capacitance. Using a larger value of output capacitance
improves the transient response of the ADP1740/ADP1741 to
large changes in load current. Figure 33 and Figure 34 show the
transient responses for output capacitance values of 4.7 µF and
22 µF, respectively.
2
CH1 1.0A Ω
BW
CH2 50.0mV
BW
M1.0µs A CH1 380mA
1
T 10.80%
T
07081-032
I
LOAD
1A/DIV
1mA TO 2A LO AD S TEP, 2.5A/µs
V
OUT
50mV/DIV
V
IN
= 3.6V , V
OUT
= 1.5V
C
IN
= C
OUT
= 4.7µF
Figure 33. Output Transient Response, COUT = 4.7 µF
2
CH1 1.0A Ω
BW
CH2 50.0mV
BW
M1.0µs A CH1 880mA
1
T 11.80%
T
07081-033
I
LOAD
1A/DIV
1mA TO 2A LO AD S TEP, 2.5A/µs
V
OUT
50mV/DIV
V
IN
= 3.6V , V
OUT
= 1.5V
C
IN
= C
OUT
= 22µF
Figure 34. Output Transient Response, COUT = 22 µF
Input Bypass Capacitor
Connecting a 4.7 µF capacitor from the VIN pin to GND
reduces the circuit sensitivity to printed circuit board (PCB)
layout, especially when long input traces or high source
impedance are encountered. If output capacitance greater than
4.7 µF is required, it is recommended that the input capacitor be
increased to match it.
Input and Output Capacitor Properties
Any good quality ceramic capacitors can be used with the
ADP1740/ADP1741, as long as they meet the minimum
capacitance and maximum ESR requirements. Ceramic
capacitors are manufactured with a variety of dielectrics, each
with different behavior over temperature and applied voltage.
Capacitors must have a dielectric adequate to ensure the
minimum capacitance over the necessary temperature range
and dc bias conditions. X5R or X7R dielectrics with a voltage
rating of 6.3 V or 10 V are recommended. Y5V and Z5U
dielectrics are not recommended, due to their poor temperature
and dc bias characteristics.
Figure 35 shows the capacitance vs. voltage bias characteristics
of an 0805 case, 4.7 μF, 1 0 V, X5R capacitor. The voltage stability
of a capacitor is strongly influenced by the capacitor size and
voltage rating. In general, a capacitor in a larger package or with
a higher voltage rating exhibits better stability. The temperature
variation of the X5R dielectric is approximately ±15% over the
−40°C to +85°C temperature range and is not a function of
package size or voltage rating.
5
4
3
2
1
00246810
CAPACITANCE ( µ F)
VOLTAGE BIAS (V)
MURAT A P / N GRM219R61A475KE 34
07081-133
Figure 35. Capacitance vs. Voltage Bias Characteristics
Use Equation 3 to determine the worst-case capacitance,
accounting for capacitor variation over temperature, com-
ponent tolerance, and voltage.
CEFF = COUT × (1 − TEMPCO) × (1 − TOL) (3)
where:
CEFF is the effective capacitance at the operating voltage.
TEMPCO is the worst-case capacitor temperature coefficient.
TOL is the worst-case component tolerance.
Rev. H | Page 14 of 20
Data Sheet ADP1740/ADP1741
In this example, the worst-case temperature coefficient
(TEMPCO) over −40°C to +85°C is assumed to be 15% for an
X5R dielectric. The tolerance of the capacitor (TOL) is assumed
to be 10%, and COUT = 4.46 μF at 1.8 V, as shown in Figure 35.
Substituting these values in Equation 3 yields
CEFF = 4.46 μF × (1 − 0.15) × (1 − 0.1) = 3.41 μF
Therefore, the capacitor chosen in this example meets the
minimum capacitance requirement of the LDO over temper-
ature and tolerance at the chosen output voltage.
To guarantee the performance of the ADP1740/ADP1741,
it is imperative that the effects of dc bias, temperature, and
tolerances on the behavior of the capacitors be evaluated for
each application.
UNDERVOLTAGE LOCKOUT
The ADP1740/ADP1741 have an internal undervoltage lockout
circuit that disables all inputs and the output when the input
voltage is less than approximately 1.58 V. This ensures that the
ADP1740/ADP1741 inputs and the output behave in a predict-
able manner during power-up.
CURRENT-LIMIT AND THERMAL OVERLOAD
PROTECTION
The ADP1740/ADP1741 are protected against damage due to
excessive power dissipation by current-limit and thermal
overload protection circuits. The ADP1740/ADP1741 are
designed to reach current limit when the output load reaches
3 A (typical). When the output load exceeds 3 A, the output
voltage is reduced to maintain a constant current limit.
Thermal overload protection is included, which limits the
junction temperature to a maximum of 150°C (typical). Under
extreme conditions (that is, high ambient temperature and power
dissipation) when the junction temperature begins to rise above
150°C, the output is turned off, reducing the output current to
zero. When the junction temperature drops below 135°C
(typical), the output is turned on again and output current is
restored to its nominal value.
Consider the case where a hard short from VOUT to ground
occurs. At first, the ADP1740/ADP1741 reach current limit so
that only 3 A is conducted into the short. If self-heating of the
junction becomes great enough to cause its temperature to rise
above 150°C, thermal shutdown activates, turning off the output
and reducing the output current to zero. As the junction temper-
ature cools and drops below 135°C, the output turns on and
conducts 3 A into the short, again causing the junction temper-
ature to rise above 150°C. This thermal oscillation between
135°C and 150°C causes a current oscillation between 3 A and
0 A that continues as long as the short remains at the output.
Current-limit and thermal overload protections are intended to
protect the device against accidental overload conditions. For
reliable operation, device power dissipation should be externally
limited so that junction temperatures do not exceed 125°C.
THERMAL CONSIDERATIONS
To guarantee reliable operation, the junction temperature of the
ADP1740/ADP1741 must not exceed 125°C. To e nsure that the
junction temperature stays below this maximum value, the user
needs to be aware of the parameters that contribute to junction
temperature changes. These parameters include ambient tem-
perature, power dissipation in the power device, and thermal
resistance between the junction and ambient air (θJA). The θJA
value is dependent on the package assembly compounds used
and the amount of copper to which the GND pin and the exposed
pad (EP) of the package are soldered on the PCB. Table 6 shows
typical θJA values for the 16-lead LFCSP for various PCB copper
sizes. Table 7 shows typical ΨJB values for the 16-lead LFCSP.
Table 6. Typical θJA Values
Copper Size (mm2) θJA (°C/W), LFCSP
01 130
100 80
500 69
1000 54
6400 42
1 Device soldered to minimum size pin traces.
Table 7. Typical ΨJB Values
Copper Size (mm2) ΨJB (°C/W) at 1 W
100 32.7
500 31.5
1000 25.5
The junction temperature of the ADP1740/ADP1741 can be
calculated from the following equation:
TJ = TA + (PD × θJA) (4)
where:
TA is the ambient temperature.
PD is the power dissipation in the die, given by
PD = [(VIN − VOUT) × ILOAD] + (VIN × IGND) (5)
where:
VIN and VOUT are the input and output voltages, respectively.
ILOAD is the load current.
IGND is the ground current.
Power dissipation due to ground current is quite small and can
be ignored. Therefore, the junction temperature equation can
be simplified as follows:
TJ = TA + {[(VIN − VOUT) × ILOAD] × θJA} (6)
As shown in Equation 6, for a given ambient temperature, input-
to-output voltage differential, and continuous load current, a
minimum copper size requirement exists for the PCB to ensure
that the junction temperature does not rise above 125°C. Figure 36
through Figure 41 show junction temperature calculations for
different ambient temperatures, load currents, VIN to VOUT
differentials, and areas of PCB copper.
Rev. H | Page 15 of 20
ADP1740/ADP1741 Data Sheet
Rev. H | Page 16 of 20
140
120
100
80
60
40
20
00.5 1.0 1.5 2.0 2.5 3.0
JUNCTI ON TEM PER ATURE ,
T
J (°C)
VIN – VOUT (V)
MAX JUNCT ION
TEMPERATURE
LOAD = 10mA
LO AD = 100mA
LO AD = 2 50mA
LOAD = 500mA
LOAD = 1A
LO AD = 2A
07081-034
Figure 36. 6400 mm2 of PCB Copper, TA = 25°C, LFCSP
140
120
100
80
60
40
20
00.5 1.0 1.5 2.0 2.5 3.0
JUNCTIO N TEMPERATURE,
T
J (°C)
VIN – VOUT (V)
MAX JUNCT ION
TEMPERATURE
LO AD = 10mA
LOAD = 100mA
LOAD = 250mA
LOAD = 500mA
LO AD = 1 A
LOAD = 2A
07081-035
Figure 37. 500 mm2 of PCB Copper, TA = 25°C, LFCSP
140
120
100
80
60
40
20
00.5 1.0 1.5 2.0 2.5 3.0
JUNCTI ON TE M P E RATURE,
T
J
(°C)
V
IN
– V
OUT
(V)
MAX JUNCT ION
TEMPERATURE
LOAD = 10mA
LOAD = 100mA
LO AD = 2 50mA
LOAD = 500mA
LOAD = 1A
07081-036
Figure 38. 0 mm2 of PCB Copper, TA = 25°C, LFCSP
140
120
100
80
60
40
20
00.5 1.0 1.5 2.0 2.5 3.0
JUNCTI ON TEM PERATUR E ,
T
J
(°C)
V
IN
– V
OUT
(V)
MAX JUNCT ION
TEMPERATURE
LOAD = 10mA
LOAD = 100mA
LOAD = 250mA
LOAD = 500mA
LO AD = 1 A
LO AD = 2 A
07081-037
Figure 39. 6400 mm2 of PCB Copper, TA = 50°C, LFCSP
140
120
100
80
60
40
20
00.5 1.0 1.5 2.0 2.5 3.0
JUNCTI ON TEM PER ATURE ,
T
J
(°C)
V
IN
– V
OUT
(V)
MAX JUNCT ION
TEMPERATURE
LOAD = 10mA
LO AD = 100mA
LOAD = 250mA
LO AD = 500mA
LOAD = 1A
LO AD = 2 A
07081-038
Figure 40. 500 mm2 of PCB Copper, TA = 50°C, LFCSP
140
120
100
80
60
40
20
00.5 1.0 1.5 2.0 2.5 3.0
JUNCTI ON TE M P E RATURE,
T
J
(°C)
V
IN
– V
OUT
(V)
MAX JUNCT ION
TEMPERATURE
LOAD = 10mA
LOAD = 100mA
LO AD = 250mA
LO AD = 500mA
LOAD = 1A
07081-039
Figure 41. 0 mm2 of PCB Copper, TA = 50°C, LFCSP
Data Sheet ADP1740/ADP1741
Rev. H | Page 17 of 20
In cases where the board temperature is known, the thermal
characterization parameter, ΨJB, can be used to estimate the
junction temperature rise. Maximum junction temperature (TJ)
is calculated from the board temperature (TB) and the power
dissipation (PD) using the following formula:
TJ = TB + (PD × ΨJB) (7)
Figure 42 through Figure 45 show junction temperature
calculations for different board temperatures, load currents,
VIN to VOUT differentials, and areas of PCB copper.
140
120
100
80
60
40
20
0
0.25 0.75 1.25 1.75 2.25 2.75
JUNCTI ON TE M P E RATURE,
T
J
(°C)
V
IN
– V
OUT
(V)
MAX JUNCT IO N
TEMPERATURE
LO AD = 10mA
LOAD = 100mA
LO AD = 250mA
LO AD = 5 00mA
LOAD = 1A
LOAD = 2A
07081-040
Figure 42. 500 mm2 of PCB Copper, TB = 25°C, LFCSP
140
120
100
80
60
40
20
0
0.25 0.75 1.25 1.75 2.25 2.75
JUNCTI ON TEM PER ATURE ,
T
J
(°C)
V
IN
– V
OUT
(V)
MAX JUNCT ION
TEMPERATURE
LOAD = 10mA
LO AD = 100mA
LOAD = 250mA
LO AD = 500mA
LOAD = 1A
LOAD = 2A
07081-041
Figure 43. 500 mm2 of PCB Copper, TB = 50°C, LFCSP
140
120
100
80
60
40
20
0
0.25 0.75 1.25 1.75 2.25 2.75
JUNCTI ON TEM PERATUR E ,
T
J
(°C)
V
IN
– V
OUT
(V)
MAX JUNCT IO N
TEMPERATURE
LOAD = 10mA
LOAD = 250mA
LO AD = 5 00mA
LOAD = 1A
LO AD = 2A
LOAD = 100mA
07081-042
Figure 44. 1000 mm2 of PCB Copper, TB = 25°C, LFCSP
140
120
100
80
60
40
20
0
0.25 0.75 1.25 1.75 2.25 2.75
JUNCTI ON TE M P E RATURE,
T
J
(°C)
V
IN
– V
OUT
(V)
MAX JUNCT ION
TEMPERATURE
LOAD = 10mA
LO AD = 2 50mA
LOAD = 500mA
LOAD = 1A
LOAD = 100mA
07081-043
LO AD = 2A
Figure 45. 1000 mm2 of PCB Copper, TB = 50°C, LFCSP
PCB LAYOUT CONSIDERATIONS
Heat dissipation from the package can be improved by increasing
the amount of copper attached to the pins of the ADP1740/
ADP1741. However, as shown in Table 6, a point of diminishing
returns is eventually reached, beyond which an increase in the
copper size does not yield significant heat dissipation benefits.
Here are a few general tips when designing PCBs:
Place the input capacitor as close as possible to the VIN
and GND pins.
Place the output capacitor as close as possible to the VOUT
and GND pins.
Place the soft start capacitor close to the SS pin.
Connect the load as close as possible to the VOUT and
SENSE pins (ADP1740) or to the VOUT and ADJ pins
(ADP1741).
Use of 0603 or 0805 size capacitors and resistors achieves the
smallest possible footprint solution on boards where area is
limited.
ADP1740/ADP1741 Data Sheet
Rev. H | Page 18 of 20
07081-044
Figure 46. Evaluation Board
07081-045
Figure 47. Typical Board Layout, Top Side
07081-046
Figure 48. Typical Board Layout, Bottom Side
Data Sheet ADP1740/ADP1741
Rev. H | Page 19 of 20
OUTLINE DIMENSIONS
COMPLIANT
TO
JEDEC S TANDARDS MO- 220 - WGGC.
111908-A
1
0.65
BSC
BOTTOM VIEWTOP VIEW
16
5
8
9
1213
4
EXPOSED
PAD
PIN 1
INDICATOR
4.10
4.00 SQ
3.90
0.70
0.60
0.50
SEATING
PLANE
0.80
0.75
0.70 0. 05 MA X
0.02 NOM
0.20 RE F
0.25 MIN
COPLANARITY
0.08
PIN 1
INDI
C
ATOR
0.35
0.30
0.25
2.25
2.10 SQ
1.95
FOR PRO PER CO NNECTION OF
THE EXPOSED PAD, REFER TO
THE P I N CO NFI G URATION AND
FUNCT ION DE S CRI P T IO NS
SECTION OF THIS DATA SHEET.
Figure 49. 16-Lead Lead Frame Chip Scale Package [LFCSP_WQ]
4 mm × 4 mm Body, Very Very Thin Quad
(CP-16-23)
Dimensions shown in millimeters
ORDERING GUIDE
Model1 Temperature Range Output Voltage (V) Package Description Package Option
ADP1740ACPZ-0.75R7 −40°C to +125°C 0.75 16-Lead LFCSP_WQ CP-16-23
ADP1740ACPZ-1.0-R7 −40°C to +125°C 1.0 16-Lead LFCSP_WQ CP-16-23
ADP1740ACPZ-1.1-R7 −40°C to +125°C 1.1 16-Lead LFCSP_WQ CP-16-23
ADP1740ACPZ-1.2-R7 −40°C to +125°C 1.2 16-Lead LFCSP_WQ CP-16-23
ADP1740ACPZ-1.3-R7 −40°C to +125°C 1.3 16-Lead LFCSP_WQ CP-16-23
ADP1740ACPZ-1.5-R7 −40°C to +125°C 1.5 16-Lead LFCSP_WQ CP-16-23
ADP1740ACPZ-1.8-R7 −40°C to +125°C 1.8 16-Lead LFCSP_WQ CP-16-23
ADP1740ACPZ-2.5-R7 −40°C to +125°C 2.5 16-Lead LFCSP_WQ CP-16-23
ADP1741ACPZ-R7 −40°C to +125°C Adjustable, 0.75 to 3.3 16-Lead LFCSP_WQ CP-16-23
ADP1740-1.5-EVALZ 1.5 Evaluation Board
ADP1741-EVALZ Adjustable Evaluation Board
1 Z = RoHS Compliant Part.
Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
Analog Devices Inc.:
ADP1741-EVALZ ADP1740-1.5-EVALZ ADP1740ACPZ-2.5-R7 ADP1740ACPZ-1.2-R7 ADP1741ACPZ-R7
ADP1740ACPZ-0.75R7 ADP1740ACPZ-1.0-R7 ADP1740ACPZ-1.1-R7 ADP1740ACPZ-1.5-R7 ADP1740ACPZ-1.8-
R7
