ADP3338AKC-18 [ADI]
High-Accuracy Ultralow IQ, 1 A, anyCAP Low Dropout Regulator; 高精度，超低IQ ， 1 ，公司的anyCAP低压差稳压器
| 型号： | ADP3338AKC-18 |
| 厂家： | 
ADI |
| 描述： | High-Accuracy Ultralow IQ, 1 A, anyCAP Low Dropout Regulator |
| 文件： | 总8页 (文件大小：144K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
®
High-Accuracy Ultralow IQ, 1 A, anyCAP
a
Low Dropout Regulator
ADP3338
FUNCTIONAL BLOCK DIAGRAM
FEATURES
High Accuracy Over Line and Load: ꢀ0.8% @ 25ꢁC,
ꢀ1.4% Over Temperature
Ultralow Dropout Voltage: 190 mV (Typ) @ 1 A
Requires Only CO = 1 ꢂF for Stability
anyCAP = Stable with Any Type of Capacitor
(Including MLCC)
Q1
OUT
IN
ADP3338
R1
R2
THERMAL
PROTECTION
CC
g
DRIVER
m
Current and Thermal Limiting
Low Noise
BANDGAP
REF
2.7 V to 8 V Supply Range
–40ꢁC to +85ꢁC Ambient Temperature Range
SOT-223 Package
GND
APPLICATIONS
Notebook, Palmtop Computers
SCSI Terminators
Battery-Powered Systems
Bar Code Scanners
Camcorders, Cameras
Home Entertainment Systems
Networking Systems
DSP/ASIC Supply
GENERAL DESCRIPTION
ADP3338
The ADP3338 is a member of the ADP33xx family of precision
low dropout anyCAP voltage regulators. The ADP3338 oper-
ates with an input voltage range of 2.7 V to 8 V and delivers a
load current up to 1 A. The ADP3338 stands out from the
conventional LDOs with a novel architecture and an enhanced
process that enables it to offer performance advantages and
higher output current than its competition. Its patented design
requires only a 1 µF output capacitor for stability. This device
is insensitive to output capacitor Equivalent Series Resistance
(ESR), and is stable with any good quality capacitor, including
ceramic (MLCC) types for space-restricted applications. The
ADP3338 achieves exceptional accuracy of 0.8% at room
temperature and 1.4% over temperature, line and load varia-
tions. The dropout voltage of the ADP3338 is only 190 mV
(typical) at 1 A. This device also includes a safety current limit
and thermal overload protection. The ADP3338 has ultralow
quiescent current 110 µA (typical) in light load situations.
V
IN
V
OUT
OUT
IN
1ꢂF
1ꢂF
GND
Figure 1. Typical Application Circuit
anyCAP is a registered trademark of Analog Devices Inc.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, norforanyinfringementsofpatentsorotherrightsofthirdpartiesthat
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
www.analog.com
© Analog Devices, Inc., 2001
(VIN = 6.0 V, CIN = COUT = 1 ꢂF, TJ = –40ꢁC to +125ꢁC, unless otherwise
noted.)
ADP3338–SPECIFICATIONS1, 2, 3
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
OUTPUT
Voltage Accuracy
VOUT
VIN = VOUTNOM + 0.4 V to 8 V
IL = 0.1 mA to 1 A
TJ = 25°C
–0.8
+0.8
%
VIN = VOUTNOM + 0.4 V to 8 V
IL = 0.1 mA to 1 A
TJ = –40°C to +125°C
VIN = VOUTNOM + 0.4 V to 8 V
IL = 50 mA to 1 A
TJ = 150 °C
–1.4
–1.6
+1.4
+1.6
%
%
Line Regulation
Load Regulation
Dropout Voltage
VIN = VOUTNOM + 0.4 V to 12 V
TJ = 25°C
0.04
mV/V
IL = 0.1 mA to 1 A
TJ = 25°C
VOUT = 98% of VOUTNOM
IL = 1 A
IL = 500 mA
IL = 100 mA
VIN = VOUTNOM + 1 V
f = 10 Hz–100 kHz, CL = 10 µF
IL = 1 A
0.006
mV/mA
VDROP
190
125
70
1.6
95
400
200
150
mV
mV
mV
A
Peak Load Current
Output Noise
ILDPK
VNOISE
µV rms
GROUND CURRENT
In Regulation
IGND
IL = 1 A
IL = 500 mA
IL = 100 mA
IL = 0.1 mA
VIN = VOUTNOM – 100 mV
IL = 0.1 mA
9
30
15
3
190
600
mA
mA
mA
µA
4.5
0.9
110
190
In Dropout
IGND
µA
NOTES
1All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.
2Application stable with no load.
3VIN = 2.7 V for models with VOUTNOM ≤ 2.2 V.
Specifications subject to change without notice.
–2–
REV. 0
ADP3338
ABSOLUTE MAXIMUM RATINGS*
PIN FUNCTION DESCRIPTIONS
Input Supply Voltage . . . . . . . . . . . . . . . . . . –0.3 V to +8.5 V
Power Dissipation . . . . . . . . . . . . . . . . . . . Internally Limited
Operating Ambient Temperature Range . . . . –40°C to +85°C
Operating Junction Temperature Range . . . –40°C to +150°C
θJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.3°C/W
θJC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26.8°C/W
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature Range (Soldering 10 sec) . . . . . . . . 300°C
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . 215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220°C
Pin
No.
Mnemonic Function
1
2
GND
OUT
Ground Pin.
Output of the Regulator. Bypass to
ground with a 1 µF or larger capacitor.
Regulator Input. Bypass to ground with
a 1 µF or larger capacitor.
3
IN
*This is a stress rating only; operation beyond these limits can cause the device to
be permanently damaged. Unless otherwise specified, all voltages are referenced
to GND.
PIN CONFIGURATION
3
2
1
IN
ADP3338
TOP VIEW
(Not to Scale)
OUT
OUT
GND
ORDERING GUIDE
Output
Voltage*
Package
Option
Package
Description
Model
ADP3338AKC-1.8
ADP3338AKC-2.5
ADP3338AKC-2.85
ADP3338AKC-3.3
ADP3338AKC-5
1.8 V
2.5 V
2.85 V
3.3 V
5 V
KC (SOT-223)
KC (SOT-223)
KC (SOT-223)
KC (SOT-223)
KC (SOT-223)
Plastic Surface Mount
Plastic Surface Mount
Plastic Surface Mount
Plastic Surface Mount
Plastic Surface Mount
*Contact the factory for other voltage options.
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the ADP3338 features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
REV. 0
–3–
(T = 25ꢁC unless otherwise noted.)
ADP3338
–Typical Performance Characteristics
A
2.504
300
2.515
V
= 6V
IN
V
I
= 2.5V
= 0A
V
= 2.5V
OUT
OUT
2.503
LOAD
I
= 0A
L
250
200
150
100
50
2.510
2.505
2.500
2.495
2.490
2.502
2.501
2.500
2.499
2.498
2.497
I
= 0.5A
L
I
= 1A
L
2.496
2.495
0
0
0.2
0.4
0.6
0.6
0.8
1.0
0
2
4
6
8
10
12
10.5
12.5
2.5
4.5
6.5
8.5
LOAD CURRENT – A
INPUT VOLTAGE – V
INPUT VOLTAGE – V
TPC 3. Ground Current vs. Supply
Voltage
TPC 2. Output Voltage vs. Load
Current
TPC 1. Line Regulation Output
Voltage vs. Supply Voltage
0.4
18
12
I = 1A
LOAD
I
= 1A
V
V
= 2.5V
V
V
= 2.5V
L
OUT
= 6V
OUT
= 6V
16
14
12
10
IN
IN
I
= 0.7A
I
= 700mA
L
LOAD
10
8
0.3
0.2
0.1
I
= 0.5A
I
= 500mA
L
LOAD
I
= 0.3A
I
= 300mA
L
LOAD
6
8
6
4
2
0
4
IL = 0A
2
0
–0.05
0
–40 –20
0
20 40 60 80 100 120 140 150
–40 –20
0
20 40 60
80 100 120
0
0.2
0.4
0.6
0.8
1.0
JUNCTION TEMPERATURE – ꢁC
JUNCTION TEMPERATURE – ꢁC
OUTPUT LOAD – A
TPC 4. Ground Current vs. Load
Current
TPC6. GroundCurrentvs. Junction
Temperature
TPC 5. Output Voltage Variation %
vs. Junction Temperature
250
V
C
R
= 2.5V
= 1ꢂF
= 2.5ꢃ
OUT
OUT
LOAD
V
R
= 2.5V
V
= 2.5V
OUT
OUT
3
2
1
0
2.51
2.50
2.49
= 2.5ꢃ
LOAD
200
150
100
50
4.5
3.5
80
120
140
180
0
1
2
3
4
5
6
7
8
9
10
TIME – sec
TIME – ꢂs
0
0
0.2
0.4
0.6
0.8
1.0
LOAD CURRENT – A
TPC 7. Dropout Voltage vs.
Load Current
TPC 9. Line Transient Response
TPC 8. Power-Up/Power-Down
–4–
REV. 0
ADP3338
V
C
R
= 6V
T
T
IN
V
C
R
= 2.5V
OUT
OUT
V
= 6V
OUT
IN
= 1ꢂF
= 10ꢂF
OUT
2.6
2.5
2.4
2.6
2.5
2.4
C
= 10ꢂF
2.51
2.50
2.49
= 2.5ꢃ
= 2.5ꢃ
LOAD
LOAD
1
0
1
0
4.5
3.5
200
400
600
800
200
300
600
800
80
120
140
180
TIME – ꢂs
TIME – ꢂs
TIME – ꢂs
TPC 10. Line Transient Response
TPC 11. Load Transient Response
TPC 12. Load Transient Response
0
300
V
= 2.5V
OUT
2.5
–10
–20
–30
–40
–50
–60
–70
–80
–90
250
200
C
L
= 1ꢂF
0.0
L
I
= 1A
C
L
= 10ꢂF
400mꢃ
L
FULL SHORT
SHORT
I
= 1A
1.5
V
= 6V
IN
150
1.0
0.5
0.0
I
= 1A
= 0A
L
100
50
0
C
L
= 1ꢂF
L
C
L
= 10ꢂF
L
I
= 0
I
= 0
0.4
0.6
TIME – s
0.8
1
I
L
0
10
20
C
30
– ꢂF
40
50
10
100
1k
10k
100k
1M
FREQUENCY – Hz
L
TPC 13. Short-Circuit Current
TPC 14. Power Supply Ripple
Rejection
TPC 15. RMS Noise vs. CL
(10 Hz–100 kHz)
100
10
1
C
= 1ꢂF
L
0.1
C
= 10ꢂF
L
0.01
0.001
10k
1k
FREQUENCY – Hz
10
100
100k
1M
TPC 16. Output Noise Density
–5–
REV. 0
ADP3338
THEORY OF OPERATION
With the ADP3338 anyCAP LDO, this is no longer true. It
can be used with virtually any good quality capacitor, with no
constraint on the minimum ESR. This innovative design allows
the circuit to be stable with just a small 1 µF capacitor on the
output. Additional advantages of the pole-splitting scheme include
superior line noise rejection and very high regulator gain, which
leads to excellent line and load regulation. An impressive 1.4%
accuracy is guaranteed over line, load, and temperature.
The new anyCAP LDO ADP3338 uses a single control loop for
regulation and reference functions. The output voltage is sensed
by a resistive voltage divider consisting of R1 and R2 which is
varied to provide the available output voltage option. Feedback
is taken from this network by way of a series diode (D1) and a
second resistor divider (R3 and R4) to the input of an amplifier.
INPUT
Q1
OUTPUT
Additional features of the circuit include current limit and ther-
mal shutdown.
COMPENSATION
CAPACITOR
ATTENUATION
R1
(V
/V
)
BANDGAP OUT
R3 D1
V
V
OUT
C
PTAT
OS
IN
LOAD
(a)
R2
NONINVERTING
WIDEBAND
DRIVER
C1
1ꢂF
C2
1ꢂF
V
g
m
PTAT
CURRENT
R
LOAD
R4
IN
OUT
GND
ADP3338
ADP3338
GND
Figure 2. Functional Block Diagram
Figure 3. Typical Application Circuit
PPLICATION INFORMATION
CAPACITOR SELECTION
Output Capacitor
The stability and transient response of the LDO is a function of
the output capacitor. The ADP3338 is stable with a wide range
of capacitor values, types, and ESR (anyCAP). A capacitor as
low as 1 µF is all that is needed for stability. A higher capacitance
may be necessary if high output current surges are anticipated or
if the output capacitor cannot be located near the output and
ground pins. The ADP3338 is stable with extremely low ESR
capacitors (ESR ≈ 0), such as Multilayer Ceramic Capacitors
(MLCC) or OSCON. Note that the effective capacitance of
some capacitor types fall below the minimum over temperature
or with dc voltage.
A very high-gain error amplifier is used to control this loop. The
amplifier is constructed in such a way that equilibrium pro-
duces a large, temperature-proportional input, “offset voltage”
that is repeatable and very well controlled. The temperature-
proportional offset voltage is combined with the complementary
diode voltage to form a “virtual bandgap” voltage, implicit in
the network, although it never appears explicitly in the circuit.
Ultimately, this patented design makes it possible to control
the loop with only one amplifier. This technique also improves
the noise characteristics of the amplifier by providing more flexibil-
ity on the trade-off of noise sources that leads to a low noise design.
A
The R1, R2 divider is chosen in the same ratio as the bandgap
voltage to the output voltage. Although the R1, R2 resistor divider
is loaded by the diode D1 and a second divider consisting of R3
and R4, the values can be chosen to produce a temperature-stable
output. This unique arrangement specifically corrects for the load-
ing of the divider, thus avoiding the error resulting from base
current loading in conventional circuits.
Input Capacitor
An input bypass capacitor is not strictly required but it is recom-
mended in any application involving long input wires or high
source impedance. Connecting a 1 µF capacitor from the
input to ground reduces the circuit’s sensitivity to PC board
layout and input transients. If a larger output capacitor is neces-
sary, a larger value input capacitor is also recommended.
The patented amplifier controls a new and unique noninverting
driver that drives the pass transistor, Q1. The use of this special
noninverting driver enables the frequency compensation to
include the load capacitor in a pole-splitting arrangement to
achieve reduced sensitivity to the value, type, and ESR of the
load capacitance.
OUTPUT CURRENT LIMIT
The ADP3338 is short-circuit protected by limiting the pass
transistor’s base drive current. The maximum output current is
limited to about 2 A. See TPC 13.
Most LDOs place very strict requirements on the range of ESR
values for the output capacitor because they are difficult to stabilize
due to the uncertainty of load capacitance and resistance. More-
over, the ESR value, required to keep conventional LDOs stable,
changes depending on load and temperature. These ESR limita-
tions make designing with LDOs more difficult because of their
unclear specifications and extreme variations over temperature.
–6–
REV. 0
ADP3338
As shown in Figures 4a–c, the amount of copper the ADP3338
is mounted to affects the thermal performance. When mounted
to 2 oz. copper with just the minimal pads, Figure 4a, the θJA is
126.6°C/W. By adding a small copper pad under the ADP3338,
Figure 4b, reduces the θJA to 102.9°C/W. Increasing the copper
pad to 1 square inch, Figure 4c, reduces the θJA even further
to 52.8°C/W.
THERMAL OVERLOAD PROTECTION
The ADP3338 is protected against damage due to excessive power
dissipation by its thermal overload protection circuit. Thermal
protection limits the die temperature to a maximum of 160°C.
Under extreme conditions (i.e., high ambient temperature and
power dissipation) where the die temperature starts to rise above
160°C, the output current will be reduced until the die tempera-
ture has dropped to a safe level.
Current and thermal limit protections are intended to protect
the device against accidental overload conditions. For normal
operation, the device’s power dissipation should be externally
limited so that the junction temperature will not exceed 150°C.
CALCULATING POWER DISSIPATION
Device power dissipation is calculated as follows:
a.
b.
c.
PD = V −VOUT × I
+ V × I
(
)
(
)
IN
LOAD
IN
GND
Figure 4. PCB Layouts
Where ILOAD and IGND are load current and ground current, VIN
and VOUT are the input and output voltages respectively.
Use the following general guidelines when designing printed
circuit boards:
Assuming worst-case operating conditions are ILOAD = 1.0 A,
GND = 10 mA, VIN = 3.3 V and VOUT = 2.5 V, the device power
dissipation is:
1. Keep the output capacitor as close to the output and ground
pins as possible.
I
2. Keep the input capacitor as close to the input and ground
pins as possible.
PD = 3.3V – 2.5V 1000 mA + 3.3V 10 mA = 833 mW
(
)
(
)
So, for a junction temperature of 125°C and a maximum ambi-
ent temperature of 85°C, the required thermal resistance from
junction to ambient is:
3. PC board traces with larger cross sectional areas will remove
more heat from the ADP3338. For optimum heat transfer,
specify thick copper and use wide traces.
4. The thermal resistance can be decreased by adding a copper
pad under the ADP3338 as shown in Figure 4b.
125°C – 85°C
θJA
=
= 48°C/W
0.833W
5. If possible, utilize the adjacent area to add more copper
around the ADP3338. Connecting the copper area to the
output of the ADP3338, as shown in Figure 4c, is best but
will improve thermal performance even if it is connected to
other signals.
PRINTED CIRCUIT BOARD LAYOUT
CONSIDERATIONS
The SOT-223’s thermal resistance, θJA, is determined by the
sum of the junction-to-case and the case-to-ambient thermal
resistances. The junction-to-case thermal resistance, θJC, is
determined by the package design and specified at 26.8°C/W.
However, the case-to-ambient thermal resistance is determined
by the printed circuit board design.
6. Use additional copper layers or planes to reduce the thermal
resistance. Again, connecting the other layers to the output
of the ADP3338 is best, but not necessary. When connecting
the output pad to other layers use multiple vias.
REV. 0
–7–
ADP3338
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
3-Lead Surface Mount
KC (SOT-223)
0.124 (3.15)
0.116 (2.95)
4
0.146 (3.70)
0.130 (3.30)
0.287 (7.30)
0.264 (6.70)
1
2
3
0.033 (0.85)
0.026 (0.65)
0.0905 (2.30)
NOM
0.041 (1.05)
0.033 (0.85)
0.051 (1.30)
0.043 (1.10)
0.264 (6.70)
0.248 (6.30)
16ꢁ
10ꢁ
0.25 (0.35)
0.067 (1.70)
0.060 (1.50)
0.010 (0.25)
16ꢁ
10ꢁ
0.181 (4.60)
NOM
10ꢁ MAX
0.004 (0.10)
0.0008 (0.02)
SEATING
PLANE
–8–
REV. 0
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