ADP1754/ADP1755评估板 PDF

Evaluation Board for the
ADP1754/ADP1755
EVAL-ADP1754/ADP1755
FEATURES
GENERAL DESCRIPTION
Input voltage range: 1.6 V to 3.6 V
Output current range: 500 μA to 1.2 A
Output voltage accuracy: ±2%
Operating temperature range: −40°C to +125°C
The ADP1754/ADP1755 evaluation board is used to demonstrate the functionality of the ADP1754/ADP1755 series of
linear regulators.
Simple device measurements, such as line and load regulation,
dropout, and ground current, can be demonstrated with just a
single voltage supply, a voltmeter, a current meter, and load
resistors.
For more details about the ADP1754/ADP1755 linear regulators,
visit www.analog.com.
07740-001
EVALUATION BOARD DIGITAL PICTURE
Figure 1.
Rev. 0
Evaluation boards are only intended for device evaluation and not for production purposes.
Evaluation boards are supplied “as is” and without warranties of any kind, express, implied, or
statutory including, but not limited to, any implied warranty of merchantability or fitness for a
particular purpose. No license is granted by implication or otherwise under any patents or other
intellectual property by application or use of evaluation boards. Information furnished by Analog
Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog
Devices for its use, nor for any infringements of patents or other rights of third parties that may result
from its use. Analog Devices reserves the right to change devices or specifications at any time
without notice. Trademarks and registered trademarks are the property of their respective owners.
Evaluation boards are not authorized to be used in life support devices or systems.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2008 Analog Devices, Inc. All rights reserved.
EVAL-ADP1754/ADP1755
TABLE OF CONTENTS
Features .............................................................................................. 1
Dropout Voltage ............................................................................5
General Description ......................................................................... 1
Ground Current Measurement ........................................................6
Evaluation Board Digital Picture .................................................... 1
Ground Current Consumption ...................................................6
Revision History ............................................................................... 2
PCB Layout Considerations .............................................................7
Evaluation Board Hardware and Schematic ................................. 3
Thermal Considerations...............................................................7
Evaluation Board Configurations .............................................. 3
Ordering Information .................................................................... 11
Output Voltage Measurement ......................................................... 4
Bill of Materials ........................................................................... 11
Line Regulation ............................................................................. 5
Ordering Guide .......................................................................... 11
Load Regulation ............................................................................ 5
ESD Caution................................................................................ 11
REVISION HISTORY
11/08—Revision 0: Initial Version
Rev. 0 | Page 2 of 12
EVAL-ADP1754/ADP1755
EVALUATION BOARD HARDWARE AND SCHEMATIC
EVALUATION BOARD CONFIGURATIONS
Figure 2 shows the schematic of this evaluation board
configuration. Table 1 lists and describes the hardware
components.
The ADP1754/ADP1755 evaluation boards are shipped with
different components depending on which version is ordered.
Components common to all versions are C1, C2, C3, R3, J1,
J2, and J3.
TP1
TP3
VOUT = 0.5V(1+R1/R2)
ADP1755 ONLY
VIN = 1.8V
15
16
C1
4.7µF
VIN
13
14
C2
4.7µF
VIN VOUT VOUT
TP4
1
2
R3
100kΩ
J1
3
VIN
VOUT
VIN
VOUT
VIN
VOUT
EN
ADP1754: SENSE/
ADP1755: ADJ
12
11
J2
R1
10
TP5
TP6
4
PG
TP2
PG
5
GND
6
SS
9
R2
NC
7
TP7
8
TP8
C3
10nF
NC = NO CONNECT
TP9
07740-002
J3
Figure 2. Evaluation Board Schematic
Table 1. Evaluation Board Hardware Components
Component
U1 1
C1
C2
C3
R1, R2
R3
J1
J2
J3
1
Function
Linear regulator
Input capacitor
Output capacitor
Soft start capacitor
Output voltage set
Pull-up resistor
Jumper
Jumper
Jumper
Description
ADP1754 or ADP1755 low dropout linear regulator.
4.7 μF input bypass capacitor.
4.7 μF output capacitor. Required for stability and transient performance.
10 nF soft start capacitor.
Not installed.
100 kΩ pull-up resistor for power good (PG).
Jumper. Connects EN to VIN for automatic startup.
Jumper. Connects SENSE to VOUT (for ADP1754 only).
Jumper. Connects Soft Start Capacitor C3.
Component varies depending on the evaluation board model ordered.
Rev. 0 | Page 3 of 12
EVAL-ADP1754/ADP1755
OUTPUT VOLTAGE MEASUREMENT
Figure 3 shows how the evaluation board can be connected to a
voltage source and a voltmeter for basic output voltage accuracy
measurements. A resistor can be used as the load for the regulator.
Ensure that the resistor has a power rating adequate to handle
the power expected to be dissipated across it. An electronic load
can be used as an alternative. In addition, ensure that the voltage
source can supply enough current for the expected load levels.
Follow these steps to connect to a voltage source and voltmeter:
2.
Connect the negative terminal (−) of the voltage source to
one of the GND pads on the evaluation board.
Connect the positive terminal (+) of the voltage source to
the VIN pad of the evaluation board.
4.
5.
Connect a load between the VOUT pad and one of the
GND pads.
Connect the negative terminal (−) of the voltmeter to one
of the GND pads.
Connect the positive terminal (+) of the voltmeter to the
VOUT pad.
The voltage source can now be turned on. If J1 is inserted
(connecting EN to VIN for automatic startup), the regulator
powers up.
If the load current is large, connect the voltmeter as close as
possible to the output capacitor to reduce the effects of IR drops.
VOLTAGE SOURCE
VOLTMETER
1.99711
+
–
+
–
LOAD
07740-003
1.
3.
Figure 3. Output Voltage Measurement Setup
Rev. 0 | Page 4 of 12
EVAL-ADP1754/ADP1755
1.520
For line regulation measurements, the regulator output is
monitored while its input is varied. For good line regulation, the output must change as little as possible with varying
input levels.
1.515
1.510
1.505
1.500
1.495
1.490
1.485
1.480
10
100
1.520
LOAD = 10mA
LOAD = 100mA
LOAD = 400mA
LOAD = 800mA
LOAD = 1.2A
1.515
10k
1.510
Figure 5. Output Voltage vs. Load Current
DROPOUT VOLTAGE
Dropout voltage can be measured using the configuration
shown in Figure 3. Dropout voltage is defined as the input-tooutput voltage differential when the input voltage is set to the
nominal output voltage. This applies only for output voltages
above 1.6 V. Dropout voltage increases with larger loads.
1.505
1.500
1.495
1.490
1.480
–40
–5
25
85
JUNCTION TEMPERATURE (°C)
125
07740-023
1.485
Figure 4. Output Voltage vs. Input Voltage
For more accurate measurements, use a second voltmeter to
monitor the input voltage across the input capacitor. The input
supply voltage may need to be adjusted to account for IR drops,
especially if large load currents are used. Figure 6 shows a
typical curve of dropout voltage measurements with different
load currents.
LOAD REGULATION
0.14
The input voltage must be held constant during this measurement.
The load current can be varied from 500 μA to 1.2 A. Figure 5
shows the typical load regulation performance of an ADP1754
with fixed 1.5 V output for an input voltage of 1.9 V.
0.12
DROPOUT VOLTAGE (V)
For load regulation measurements, the output of the regulator
is monitored while the load is varied. For good load regulation,
the output must change as little as possible with varying loads.
0.10
0.08
0.06
0.04
1.6V
2.5V
0.02
0
1
10
100
LOAD CURRENT (mA)
1k
Figure 6. Dropout Voltage vs. Load Current
Rev. 0 | Page 5 of 12
10k
07740-006
OUTPUT VOLTAGE (V)
1k
LOAD CURRENT (mA)
07740-024
To ensure that the device is not in dropout mode during this
measurement, VIN must be varied between VOUTNOM + 0.4 V
(or + 1.6 V, whichever is greater) and VINMAX. For example, for
an ADP1754 with fixed 1.5 V output, VIN needs to be varied
between 1.9 V and 3.6 V. This measurement can be repeated
under different load conditions. Figure 4 shows the typical line
regulation performance of an ADP1754 with fixed 1.5 V output.
OUTPUT VOLTAGE (V)
LINE REGULATION
EVAL-ADP1754/ADP1755
GROUND CURRENT MEASUREMENT
Follow these steps to connect to a voltage source and ammeter:
2.
3.
4.
Connect the positive terminal (+) of the voltage source to
the VIN pad on the evaluation board.
Connect the positive terminal (+) of the ammeter to one of
the GND pads of the evaluation board.
Connect the negative terminal (−) of the ammeter to the
negative (−) terminal of the voltage source.
Connect a load between the VOUT pad of the evaluation
board and the negative (−) terminal of the voltage source.
The voltage source can now be turned on. If J1 is inserted (EN
is connected to VIN for automatic startup), the regulator
powers up.
Ground current measurements can determine how much
current the internal circuits of the regulator are consuming
while the circuits perform the regulation function. To be
efficient, the regulator needs to consume as little current as
possible. Typically, the regulator uses the maximum current
when supplying its largest load level (1.2 A). Figure 7 shows the
typical ground current consumption for various load levels at
VIN = 1.9 V. When the device is disabled (EN = GND), ground
current drops to less than 6 µA.
1200
1000
800
600
400
200
0
10
100
1k
10k
LOAD CURRENT (mA)
Figure 7. Ground Current vs. Load Current
VOLTAGE SOURCE
AMMETER
0.00112
–
–
+
LOAD
07740-007
+
Figure 8. Ground Current Measurement
Rev. 0 | Page 6 of 12
07740-025
1.
GROUND CURRENT CONSUMPTION
GROUND CURRENT (µA)
Figure 8 shows how the evaluation board can be connected to a
voltage source and an ammeter for ground current measurements. A resistor can be used as the load for the regulator.
Ensure that the resistor has a power rating adequate to handle
the power expected to be dissipated across it. An electronic load
can be used as an alternative. Ensure that the voltage source used
can supply enough current for the expected load levels.
EVAL-ADP1754/ADP1755
PCB LAYOUT CONSIDERATIONS
Heat dissipation from the package can be improved by increasing the amount of copper attached to the pins of the ADP1754/
ADP1755. However, as shown in Table 2, 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 (ADP1754) or to the VOUT and ADJ pins
(ADP1755).
07740-010

Use of 0603 or 0805 size capacitors and resistors achieves the
smallest possible footprint solution on boards where area is
limited.
Figure 10. Typical Board Layout, Bottom Side
THERMAL CONSIDERATIONS
To guarantee reliable operation, the junction temperature of the
ADP1754/ADP1755 must not exceed 125°C. To ensure 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 temperature, 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 pins of the package are
soldered on the PCB. Table 2 shows typical θJA values of the 16-lead
LFCSP for various PCB copper sizes. Table 3 shows the typical
ΨJB value of the 16-lead LFCSP.
07740-009
Table 2. Typical θJA Values
Figure 9. Typical Board Layout, Top Side
Copper Size (mm2)
01
100
500
1000
6400
1
θJA (°C/W), LFCSP
130
80
69
54
42
Device soldered to minimum size pin traces.
Table 3. Typical ΨJB Values
Copper Size (mm2)
100
500
1000
Rev. 0 | Page 7 of 12
ΨJB (°C/W) @ 1W
32.7
31.5
25.5
EVAL-ADP1754/ADP1755
(1)
where:
TA is the ambient temperature.
PD is the power dissipation in the die, given by
PD = [(VIN − VOUT) × ILOAD] + (VIN × IGND)
(2)
where:
VIN and VOUT are the input and output voltages, respectively.
ILOAD is the load current.
IGND is the ground current.
120
LOAD = 1.2A
LOAD = 800mA
80
LOAD = 200mA
60
LOAD = 100mA
40
LOAD = 10mA
20
0
0.25
TJ = TA + {[(VIN − VOUT) × ILOAD] × θJA}
2.25
2.75
JUNCTION TEMPERATURE, TJ (°C)
MAX JUNCTION
TEMPERATURE
120
LOAD = 1.2A
100
LOAD =
800mA
80
LOAD = 400mA
LOAD = 200mA
60
LOAD = 100mA
40
LOAD = 10mA
20
0
0.25
0.75
1.25
1.75
VIN – VOUT (V)
2.25
2.75
07740-028
LOAD = 800mA
100
80
1.25
1.75
VIN – VOUT (V)
140
120
Figure 13. 0 mm2 of PCB Copper, TA = 25°C, LFCSP
LOAD = 400mA
60
LOAD = 200mA
20
LOAD = 10mA
0
0.25
0.75
1.25
1.75
VIN – VOUT (V)
2.25
2.75
Figure 11. 6400 mm2 of PCB Copper, TA = 25°C, LFCSP
MAX JUNCTION
TEMPERATURE
120
LOAD = 800mA
LOAD = 1.2A
100
LOAD = 400mA
80
LOAD = 200mA
60
LOAD = 10mA
40
LOAD = 100mA
20
0
0.25
0.75
1.25
1.75
VIN – VOUT (V)
2.25
Figure 14. 6400 mm2 of PCB Copper, TA = 50°C, LFCSP
Rev. 0 | Page 8 of 12
2.75
07740-029
LOAD = 100mA
JUNCTION TEMPERATURE, TJ (°C)
140
40
07740-026
JUNCTION TEMPERATURE, TJ (°C)
MAX JUNCTION
TEMPERATURE
0.75
Figure 12. 500 mm2 of PCB Copper, TA = 25°C, LFCSP
(3)
As shown in Equation 3, for a given ambient temperature, inputto-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 11
through Figure 16 show junction temperature calculations for
different ambient temperatures, load currents, VIN to VOUT
differentials, and areas of PCB copper.
LOAD = 1.2A
LOAD = 400mA
100
Power dissipation due to ground current is quite small and can
be ignored. Therefore, the junction temperature equation can
be simplified as follows:
140
MAX JUNCTION
TEMPERATURE
07740-027
TJ = TA + (PD × θJA)
JUNCTION TEMPERATURE, TJ (°C)
140
The junction temperature of the ADP1754/ADP1755 can be
calculated from the following equation:
EVAL-ADP1754/ADP1755
140
120
LOAD = 800mA
LOAD = 400mA
100
80
TJ = TB + (PD × ΨJB)
LOAD = 200mA
LOAD = 10mA
140
MAX JUNCTION
TEMPERATURE
JUNCTION TEMPERATURE, TJ (°C)
40
20
0.75
1.25
1.75
VIN – VOUT (V)
2.25
2.75
Figure 15. 500 mm2 of PCB Copper, TA = 50°C, LFCSP
140
MAX JUNCTION
TEMPERATURE
LOAD = 1.2A
120
LOAD =
800mA
120
LOAD = 1.2A
100
LOAD = 800mA
80
LOAD = 400mA
60
LOAD = 200mA
40
LOAD = 10mA
20
LOAD = 100mA
LOAD = 400mA
0
0.25
100
LOAD = 200mA
80
0.75
1.25
1.75
VIN – VOUT (V)
2.25
2.75
07740-032
0
0.25
Figure 17. 500 mm2 of PCB Copper, TB = 25°C, LFCSP
LOAD = 100mA
60
140
MAX JUNCTION
TEMPERATURE
JUNCTION TEMPERATURE, TJ (°C)
20
0
0.25
0.75
1.25
1.75
VIN – VOUT (V)
2.25
2.75
Figure 16. 0 mm2 of PCB Copper, TA = 50°C, LFCSP
120
LOAD = 1.2A
LOAD = 800mA
100
LOAD = 400mA
80
LOAD = 200mA
60
LOAD = 10mA
40
LOAD = 100mA
20
0
0.25
0.75
1.25
1.75
VIN – VOUT (V)
2.25
Figure 18. 500 mm2 of PCB Copper, TB = 50°C, LFCSP
Rev. 0 | Page 9 of 12
2.75
07740-033
LOAD = 10mA
40
07740-031
JUNCTION TEMPERATURE, TJ (°C)
(4)
LOAD = 100mA
60
07740-030
JUNCTION TEMPERATURE, TJ (°C)
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 power
dissipation (PD) using the following formula:
MAX JUNCTION
TEMPERATURE
LOAD = 1.2A
EVAL-ADP1754/ADP1755
140
MAX JUNCTION
TEMPERATURE
JUNCTION TEMPERATURE, TJ (°C)
120
100
LOAD = 1.2A
LOAD = 800mA
80
60
LOAD = 400mA
LOAD = 200mA
40
LOAD = 10mA
20
MAX JUNCTION
TEMPERATURE
120
LOAD = 1.2A
LOAD = 800mA
100
LOAD = 400mA
80
LOAD = 200mA
60
LOAD = 10mA
40
LOAD = 100mA
20
0
0.25
0.75
1.25
1.75
VIN – VOUT (V)
2.25
2.75
Figure 19. 1000 mm2 of PCB Copper, TB = 25°C, LFCSP
0
0.25
0.75
1.25
1.75
VIN – VOUT (V)
2.25
Figure 20. 1000 mm2 of PCB Copper, TB = 50°C, LFCSP
Rev. 0 | Page 10 of 12
2.75
07740-035
LOAD = 100mA
07740-034
JUNCTION TEMPERATURE, TJ (°C)
140
EVAL-ADP1754/ADP1755
ORDERING INFORMATION
BILL OF MATERIALS
Table 4
Qty
2
1
3
1
2
1
Reference Designator
C1, C2
C3
J1, J2, J3
R3
R1, R2
U1
Description
Capacitor, MLCC, 4.7 μF, 6.3 V, 0805, X5R
Capacitor, MLCC, 10 nF, 50 V, 0603, X5R
Header, single, STR, 2 pins
Resistor, 100 kΩ, 0.10 W, 0603
Resistor, 0.10 W, 0603
IC, LDO regulator
ESD CAUTION
ORDERING GUIDE
Model
ADP1754-1.5-EVALZ1
Output Voltage (V)
1.5
ADP1755-EVALZ1
Adjustable
1
Manufacturer/Vendor
Murata or equivalent
Murata or equivalent
Digi-Key Corp.
Vishay or equivalent
Vishay or equivalent
Analog Devices, Inc.
Description
Fixed 1.5 V Output
Evaluation Board
Adjustable Output
Evaluation Board
Z = RoHS Compliant Part.
Rev. 0 | Page 11 of 12
Vendor Part No.
GRM219R61A475KE34
GRM188R71H103KA01
S1012E-36-ND
CRCW0603100KFKEA
Not installed
ADP1755ACPZ-R7,
ADP1754ACPZ-1.5-R7
EVAL-ADP1754/ADP1755
NOTES
©2008 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
EB07740-0-11/08(0)
Rev. 0 | Page 12 of 12
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