High Accuracy, Low IQ, anyCAP
Adjustable Low Dropout Regulator
®
ADP3334
FEATURES
High Accuracy over Line and Load: 0.9% @ 25C,
1.8% over Temperature
500 mA Current Capability
Ultralow Dropout Voltage
Requires Only C
= 1.0 F for Stability
O
anyCAP = Stable with Any Type of Capacitor
(Including MLCC)
Current and Thermal Limiting
Low Noise
Low Shutdown Current: < 1.0 A (Typ)
2.6 V to 11 V Supply Range
1.5 V to 10 V Output Range
–40C to +85C Ambient Temperature Range
APPLICATIONS
Cellular Phones
TFT LCD Modules
Camcorders, Cameras
Networking Systems, DSL/Cable Modems
Cable Set-Top Boxes
DSP Supplies
Personal Digital Assistants
GENERAL DESCRIPTION
The ADP3334 is a member of the ADP333x family of precision
low dropout anyCAP voltage regulators. The ADP3334 operates
with an input voltage range of 2.6 V to 11 V and delivers a
continuous load current up to 500 mA. The novel anyCAP
architecture requires only a very small 1 µF output capacitor for
stability, and the LDO is insensitive to the capacitor’s equivalent
series resistance (ESR). This makes the ADP3334 stable with any
capacitor, including ceramic (MLCC) types for space restricted
applications.
The ADP3334 achieves exceptional accuracy of ±0.9% at room
temperature and ±1.8% over temperature, line, and load. The
dropout voltage of the ADP3334 is only 200 mV (typical) at
500 mA. This device also includes a safety current limit, thermal overload protection, and a shutdown feature. In shutdown
mode, the ground current is reduced to less than 1 µA. The
ADP3334 has low quiescent current of 90 µA (typical) in light
load situations.
FUNCTIONAL BLOCK DIAGRAM
SD
IN
THERMAL
PROTECTION
Q1
DRIVER
GND
CC
ADP3334
g
m
BAND GAP
REF
OUT
FB
The ADP3334 is available in three different package options:
1. Excellent thermal capability, space saving 3 mm ⫻ 3 mm LFCSP.
2. Popular low profile MSOP-8.
3. Traditional thermal enhanced SOIC-8.
ADP3334
SD
GND
OUT
OUT
V
C
1F
OUT
OUT
C
R1
FB
NR
R2
IN
V
IN
C
IN
1F
IN
OFF
ON
Figure 1. Typical Application Circuit
REV. B
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. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 www.analog.com
Fax: 781/326-8703 © 2003 Analog Devices, Inc. All rights reserved.
ADP3334–SPECIFICATIONS
1, 2, 3
(VIN = 6.0 V, CIN = C
= 1.0 F, TA = –40C to +85C, unless otherwise noted.)
OUT
Parameter Symbol Conditions Min Typ Max Unit
OUTPUT
Voltage Accuracy
4
V
OUT
VIN = V
I
T
V
I
OUT(NOM)
= 0.1 mA to 500 mA
L
= 25°C
A
= V
IN
OUT(NOM)
= 0.1 mA to 500 mA
L
+ 0.4 V to 11 V –0.9 +0.9 %
+ 0.4 V to 11 V –1.8 +1.8 %
TA = 85°C
Line Regulation
= V
V
IN
OUT(NOM)
= 0.1 mA to 500 mA
I
L
4
TJ = 150°C
VIN = V
I
OUT(NOM)
= 0.1 mA
L
+ 0.4 V to 11 V –2.3 +2.3 %
+ 0.4 V to 11 V 0.04 mV/V
TA = 25°C
Load Regulation I
Dropout Voltage V
DROP
= 0.1 mA to 500 mA 0.04 mV/mA
L
= 25°C
T
A
V
= 98% of V
OUT
OUT(NOM)
IL = 500 mA 200 400 mV
I
= 300 mA 140 250 mV
L
= 100 mA 60 140 mV
I
L
= 1 mA 10 mV
I
Peak Load Current I
Output Noise V
LDPK
NOISE
L
VIN = V
OUT(NOM)
+ 1 V 800 mA
f = 10 Hz–100 kHz, CL = 10 µF 27 µV rms
= 500 mA, CNR = 10 nF
I
L
f = 10 Hz–100 kHz, C
= 10 µF 45 µV rms
L
IL = 500 mA, CNR = 0 nF
GROUND CURRENT
In Regulation I
In Dropout I
In Shutdown I
5
GND
GND
GNDSD
IL = 500 mA 4.5 10 mA
= 300 mA 2.6 6 mA
I
L
= 50 mA 0.5 1.5 mA
I
L
I
= 0.1 mA 90 130 µA
L
VIN = V
= 0.1 mA
I
L
OUT(NOM)
– 100 mV 150 450 µA
SD = 6 V, VIN = 11 V 0.9 3 µA
SHUTDOWN
Threshold Voltage V
THSD
LDO OFF 2.0 V
LDO ON 0.4 V
SD Input Current I
Output Current in Shutdown I
NOTES
1
All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC) methods.
2
Ambient temperature of 85°C corresponds to a junction temperature of 125°C under pulsed full load test conditions.
3
Application stable with no load.
4
VIN = 2.6 V to 11 V for V
5
Ground current includes current through external resistors.
Specifications subject to change without notice.
OUT(NOM)
£ 2.2 V.
SD
OSD
0 £ SD £ 5 V 1.2 3 µA
SD = 2 V, VIN = 11 V 0.01 5 µA
REV. B–2–
ADP3334
TOP VIEW
(Not to Scale)
8
7
6
5
1
2
3
4
GND
SD
IN
IN
NC
FB
OUT
OUT
ADP3334AR
NC = NO CONNECT
ABSOLUTE MAXIMUM RATSINGS*
Input Supply Voltage . . . . . . . . . . . . . . . . . . . –0.3 V to +16 V
Shutdown Input Voltage . . . . . . . . . . . . . . . . –0.3 V to +16 V
Power Dissipation . . . . . . . . . . . . . . . . . . . . Internally Limited
Operating Ambient Temperature Range . . . . –40°C to +85°C
Operating Junction Temperature Range . . . –40°C to +150°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
2-Layer SOIC-8 . . . . . . . . . . . . . . . . . . . . . . . . 122.3°C/W
JA
4-Layer SOIC-8 . . . . . . . . . . . . . . . . . . . . . . . . . 86.6°C/W
JA
2-Layer LFCSP-8 . . . . . . . . . . . . . . . . . . . . . . . . . . 62°C/W
JA
4-Layer LFCSP-8 . . . . . . . . . . . . . . . . . . . . . . . . . . 48°C/W
JA
2-Layer MSOP-8 . . . . . . . . . . . . . . . . . . . . . . . . . 220°C/W
JA
4-Layer MSOP-8 . . . . . . . . . . . . . . . . . . . . . . . . . 158°C/W
JA
Lead Temperature Range (Soldering 6 sec) . . . . . . . . . . 300°C
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only. Functional operation of the
device at these or any other conditions above those listed in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
PIN CONFIGURATIONS
OUT
OUT
FB
NC
1
2
3
4
ADP3334ARM
TOP VIEW
(Not to Scale)
NC = NO CONNECT
8
IN
7
IN
6
SD
5
GND
OUT
OUT
FB
NC
1
2
3
4
ADP3334ACP
TOP VIEW*
*PINS UNDERSIDE
NC = NO CONNECT
PIN FUNCTION DESCRIPTIONS
Mnemonic Function
GND Ground Pin.
SD Shutdown Control. Pulling this pin low
turns on the regulator.
IN Regulator Input.
OUT Output. Bypass to ground with a 1.0 µF or
larger capacitor.
FB Feedback Input. FB should be connected to
an external resistor divider that sets the
output voltage.
NC No Connection.
8
IN
7
IN
6
SD
5
GND
ORDERING GUIDE
Package Package
Model Output Description Option Brand
ADP3334AR ADJ Standard Small Outline RN-8
Package (SOIC-8)
ADP3334ACP ADJ Lead Frame Chip CP-8 LLA
Scale Package (LFCSP)
3 mm ⫻ 3 mm Body, 8-Lead
ADP3334ARM ADJ MSOP Package RM-8 LLA
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 ADP3334 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.
REV. B
–3–
ADP3334–Typical Performance Characteristics
2.202
IL = 0
2.201
2.200
2.199
150mA
2.198
2.197
300mA
2.196
OUTPUT VOLTAGE – V
2.195
2.194
24 12
500mA
6810
INPUT VOLTAGE – V
V
OUT
TPC 1. Line Regulation Output
Voltage vs. Supply Voltage
5.0
VIN = 6V
= 2.2V
V
OUT
4.0
3.0
2.0
1.0
GROUND CURRENT – mA
0
0 100 500
200 300 400
OUTPUT LOAD – mA
TPC 4. Ground Current vs.
Load Current
= 2.2V
2.201
2.200
2.199
2.198
2.197
2.196
2.195
OUTPUT VOLTAGE – V
2.194
2.193
0 100 500
200 300 400
OUTPUT LOAD – mA
V
= 2.2V
OUT
V
= 6V
IN
TPC 2. Output Voltage vs.
Load Current
0.5
0.4
0.3
0.2
0.1
0
OUTPUT CHANGE – %
500mA
–0.1
0
–0.2
–50 125
–25 0 25 50 75 100
JUNCTION TEMPERATURE – C
0mA
300mA
500mA
TPC 5. Output Voltage Variation %
vs. Junction Temperature
150
140
120
100
80
60
40
GROUND CURRENT – A
20
0
IL = 100A
IL = 0
24 68 10
012
INPUT VOLTAGE – V
V
= 2.2V
OUT
TPC 3. Ground Current vs.
Supply Voltage
8
IL = 500mA
7
6
5
300mA
4
3
100mA
2
GROUND CURRENT – mA
50mA
1
0
0
–50 125
–25 0 25 50 75 100
JUNCTION TEMPERATURE – C
VIN = 6V
V
= 2.2V
OUT
150
TPC 6. Ground Current vs.
Junction Temperature
250
V
= 2.2V
OUT
200
150
100
50
DROPOUT VOLTAGE – mV
0
0 100 500
200 300 400
OUTPUT LOAD – mA
TPC 7. Dropout Voltage vs.
Output Current
V
3.0
2.5
2.0
1.5
1.0
0.5
0
INPUT/OUTPUT VOLTAGE – V
1 234
TIME – s
OUT
SD = GND
= 4.4
R
L
TPC 8. Power-Up/Power-Down
= 2.2V
3
– V
C
= 1F
OUT
2
OUT
1
0
4
– V V
2
IN
V
0
C
= 10F
OUT
200 400 600 800
TIME – s
TPC 9. Power-Up Response
V
= 2.2V
OUT
SD = GND
= 4.4
R
L
REV. B–4–
ADP3334
2.210
– V
2.200
OUT
V
– V
IN
V
2.190
2.180
2.170
3.500
3.000
40 80 140 180
TIME – s
V
OUT
R
L
C
L
= 2.2V
= 4.4
= 1F
TPC 10. Line Transient Response
2.3
– V
2.2
OUT
2.1
400
V
– mA V
OUT
I
200
0
= 2.2V
OUT
V
= 6V
IN
C
= 10F
L
200 400 600 800
TIME – s
TPC 13. Load Transient Response
2.210
– V
2.200
OUT
V
– V
IN
V
2.190
2.180
2.170
3.500
3.000
40 80 140 180
TIME – s
V
OUT
R
L
C
L
= 4.4
= 10F
TPC 11. Line Transient Response
2.2
– V
OUT
0
V
FULL SHORT
V
= 4V
IN
– A
OUT
I
3
2
1
0
800m
SHORT
200 400 600 800
TIME – s
TPC 14. Short Circuit Current
= 2.2V
2.3
– V
2.2
OUT
V
2.1
400
200
– mA
OUT
I
0
VIN = 6V
V
= 2.2V
OUT
C
= 1F
L
200 400 600 800
TIME – s
TPC 12. Load Transient Response
1F
– V
OUT
V
– V
SD
V
2
1
0
2
0
10F
200 400 600 800
VIN = 6V
V
OUT
= 4.4
R
L
TIME – s
1F
= 2.2V
10F
TPC 15. Turn Off/On Response
–20
V
= 2.2V
OUT
–30
–40
CL = 1F
–50
I
–60
–70
RIPPLE REJECTION – dB
–80
–90
10 100 1k 10k 100k 1M 10M
= 50A
L
CL = 1F
= 500mA
I
L
FREQUENCY – Hz
CL = 10F
= 500mA
I
L
CL = 10F
= 50A
I
L
TPC 16. Power Supply Ripple
Rejection
160
140
120
100
80
60
RMS NOISE – V
40
20
0
05010 20 30 40
IL = 500mA WITHOUT
NOISE REDUCTION
IL = 500mA WITH
NOISE REDUCTION
IL = 0mA WITH NOISE REDUCTION
– F
C
L
TPC 17. RMS Noise vs. C
(10 Hz to 100 kHz)
V
= 2.0V
OUT
= 10nF
C
NR
IL = 0mA WITHOUT
NOISE REDUCTION
L
100
10
CL = 10F
C
NR
1
0.1
DENSITY – V/ Hz
0.01
VOLTAGE NOISE SPECTRAL
0.001
10 100 1M1k 10k 100k
CL = 10F
C
= 10nF
NR
CL = 1F
= 10nF
C
NR
FREQUENCY – Hz
= 0
V
I
CL = 1F
C
NR
TPC 18. Output Noise Density
OUT
= 1mA
L
= 0
= 2.2V
REV. B
–5–
ADP3334
THEORY OF OPERATION
The new anyCAP LDO ADP3334 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 that 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
NONINVERTING
WIDEBAND
DRIVER
COMPENSATION
CAPACITOR
ADP3334
ATTENUATION
(V
BANDGA P/VOUT
R3
PTAT
V
OS
g
m
R4
GND
PTAT
CURRENT
OUTPUT
)
R1
C
D1
FB
LOAD
(a)
R
LOAD
R2
Figure 2. Functional Block Diagram
A very high gain error amplifier is used to control this loop. The
amplifier is constructed in such a way that equilibrium produces a large, temperature-proportional input, “offset voltage”
that is repeatable and very well controlled. The temperatureproportional offset voltage is combined with the complementary
diode voltage to form a “virtual band gap” 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
flexibility on the trade-off of noise sources that leads to a low
noise design.
The R1, R2 divider is chosen in the same ratio as the band gap
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
loading of the divider, thus avoiding the error resulting from
base current loading in conventional circuits.
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.
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. Moreover, the ESR value, required to keep conventional LDOs stable,
changes depending on load and temperature. These ESR limitations make designing with LDOs more difficult because of their
unclear specifications and extreme variations over temperature.
With the ADP3334 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 mF capacitor on the output. Additional advantages of the pole-splitting scheme include
superior line noise rejection and very high regulator gain, which
lead to excellent line and load regulation. An impressive ±1.8%
accuracy is guaranteed over line, load, and temperature.
Additional features of the circuit include current limit and thermal shutdown.
APPLICATION INFORMATION
Output Capacitor
As with any micropower device, output transient response is a
function of the output capacitance. The ADP3334 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;
larger capacitors can be used if high output current surges are
anticipated. The ADP3334 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 may fall below the minimum over the operating
temperature range or with the application of a dc voltage.
Input Bypass Capacitor
An input bypass capacitor is not strictly required but is advisable
in any application involving long input wires or high source
impedance. Connecting a 1 µF capacitor from IN to ground
reduces the circuit’s sensitivity to PC board layout. If a larger
value output capacitor is used, then a larger value input capacitor is also recommended.
Noise Reduction Capacitor
A noise reduction capacitor (CNR) can be placed between the
output and the feedback pin to further reduce the noise by
6dB to 10 dB (TPC 18). Low leakage capacitors in the 100 pF
to 1 nF range provide the best performance. Since the feedback
pin (FB) is internally connected to a high impedance node, any
connection to this node should be carefully done to avoid noise
pickup from external sources. The pad connected to this pin
should be as small as possible, and long PC board traces are not
recommended.
When adding a noise reduction capacitor, maintain a minimum load current of 1 mA when not in shutdown.
It is important to note that as C
will be delayed. With C
NR
increases, the turn-on time
NR
values of 1 nF, this delay may be
on the order of several milliseconds.
ADP3334
SD
GND
OUT
OUT
FB
R1
R2
V
C
1F
OUT
OUT
C
NR
IN
V
IN
C
IN
1F
IN
OFF
ON
Figure 3. Typical Application Circuit
Output Voltage
The ADP3334 has an adjustable output voltage that can be set
by an external resistor divider. The output voltage will be divided
by R1 and R2 and then fed back to the FB pin.
REV. B–6–
ADP3334
V.V
.
.
V.V
Resistor Divider Error
.
.
OUT
OUT
=¥+
Ê
Ë
Á
ˆ
¯
˜
=
=-
Ê
Ë
Á
ˆ
¯
˜
¥=-
1 178
138 6
79 5
1
3 232
3 232
33
1 100 2 1%.%
To have the lowest possible sensitivity of the output voltage to
temperature variations, it is important that the value of the parallel
resistance of R1 and R2 be kept as close as possible to 50 kW.
RR
12
¥
RR
12
+
k
50
=W
(1)
Also, for the best accuracy over temperature, the feedback voltage should be set for 1.178 V:
VV
where V
=¥
FB OUT
OUT
Ê
Á
Ë
RR
is the desired output voltage and VFB is the virtual
band gap voltage. Note that V
ˆ
2
R
˜
¯
12
+
FB
(2)
does not actually appear at the
FB pin due to loading by the internal PTAT current.
Combining the above equations and solving for R1 and R2 gives
the following formulas:
Ê
ˆ
V
Rk
150=¥
R
V
(V) R1 (1% Resistor) (k) R2 (1% Resistor) (k)
OUT
50
2
Ê
1=-
Á
Ë
Table I. Feedback Resistor Selection
OUT
W
Á
˜
V
Ë
¯
FB
W
k
ˆ
V
FB
˜
V
¯
OUT
(3)
(4)
1.5 63.4 232.0
1.8 76.8 147.0
2.2 93.1 107.0
2.7 115.0 88.7
3.3 140.0 78.7
5.0 210.0 64.9
10.0 422.0 56.2
Using standard 1% values, as shown in Table I, will sacrifice
some output voltage accuracy. To estimate the overall output
voltage accuracy, it is necessary to take into account all sources
of error. The accuracy given in the specifications table does not
take into account the error introduced by the feedback resistor
divider ratio or the error introduced by the parallel combination
of the feedback resistors.
The error in the parallel combination of the feedback resistors
causes the reference to have a wider variation over temperature.
To estimate the variation, calculate the worst-case error from
50 kW, and then use the graph in Figure 4 to estimate the
additional change in the output voltage over the operating
temperature range.
For example:
V
= 5 V
IN
V
= 3.3 V
OUT
R1 = 140 kW, 1%
R2 = 78.7 kW, 1%
3.0
2.5
2.0
1.5
1.0
OUTPUT ERROR – %
0.5
0
023456
Rp ERROR – %
Figure 4. Output Voltage Error vs.
Parallel Resistance Error
The actual output voltage can be calculated using the following
equation.
V.V
=¥+
1 178
OUT
V.V
=
3 274
OUT
Ê
Á
Ë
ˆ
R
1
1
˜
R
2
¯
(5)
So worst-case error will occur when R1 has a –1% tolerance and
R2 has a +1% tolerance. Recalculating the output voltage, the
parallel resistance and error are:
(6)
RR
¥
R
PARALLEL
R Error
PARALLEL
12
=
RR
+
12
=-
Ê
Á
Ë
..
138 6 79 5
=
..
138 6 79 5
.
50 51
1 100 1 02
50
¥
+
ˆ
¥=
˜
¯
. k
=
50 51
%.%
W
(7)
So, from the graph in Figure 4, the output voltage error is
estimated to be an additional 0.25%. The error budget is
1.8% (the initial output voltage accuracy over temperature),
plus 2.1% (resistor divider error), plus 0.25% (parallel resistance error) for a worst-case total of 4.15%.
Thermal Overload Protection
The ADP3334 is protected against damage from excessive power
dissipation by its thermal overload protection circuit, which limits
the die temperature to a maximum of 165°C. Under extreme
conditions (i.e., high ambient temperature and power dissipation)
where die temperature starts to rise above 165°C, the output
current is reduced until the die temperature has dropped to a safe
level. The output current is restored when the die temperature
is reduced.
REV. B
–7–
ADP3334
Current and thermal limit protections are intended to protect
the device against accidental overload conditions. For normal
operation, device power dissipation should be externally limited
so that junction temperatures will not exceed 150°C.
Calculating Junction Temperature
Device power dissipation is calculated as follows:
PVV I VI
=-
()
DINOUT LOAD IN GND
where I
and V
Assuming I
V
OUT
and I
LOAD
are input and output voltages, respectively.
OUT
LOAD
are load current and ground current, V
GND
= 400 mA, I
= 2.8 V, device power dissipation is:
PmAmAmW
=-
()+()
D
+
()
= 4 mA, VIN = 5.0 V and
GND
=528400 5 0 4 900..
(8)
IN
(9)
As an example, the proprietary package used in the ADP3334
has a thermal resistance of 86.6°C/W, significantly lower than
a standard SOIC-8 package. Assuming a 4-layer board, the
junction temperature rise above ambient temperature will be
approximately equal to:
DT=. W CW C
0 900 86 6 77 9¥ ∞ = ∞./ .
A
J
(10)
To limit the maximum junction temperature to 150°C, maximum allowable ambient temperature will be:
TC/WC
= ∞ - ∞ = ∞150 77 9 72 1C ..
AMAX
(11)
The maximum power dissipation versus ambient temperature
for each package is shown in Figure 5.
3.5
3.0
2.5
2.0
1.5
1.0
POWER DISSIPATION – W
158C/W MSOP
0.5
0
–20 0 20 406080
48C/W LFCSP
62C/W LFCSP
86C/W SOIC
122C/W SOIC
220C/W MSOP
AMBIENT TEMPERATURE – C
Figure 5. Power Derating Curve
Printed Circuit Board Layout Consideration
All surface-mount packages rely on the traces of the PC board
to conduct heat away from the package.
In standard packages, the dominant component of the heat
resistance path is the plastic between the die attach pad and the
individual leads. In typical thermally enhanced packages, one or
more of the leads are fused to the die attach pad, significantly
decreasing this component. To make the improvement meaningful, however, a significant copper area on the PCB must be
attached to these fused pins.
As an example, the patented thermal coastline lead frame design
of the ADP3334 uniformly minimizes the value of the dominant
portion of the thermal resistance. It ensures that heat is conducted away by all pins of the package. This yields a very low
86.6°C/W thermal resistance for the SOIC-8 package, without
any special board layout requirements, relying only on the normal
traces connected to the leads. This yields a 15% improvement in
heat dissipation capability as compared to a standard SOIC-8
package. The thermal resistance can be decreased by an additional 10% by attaching a few square centimeters of copper area
to the IN or OUT pins of the ADP3334 package.
It is not recommended to use solder mask or silkscreen on the
PCB traces adjacent to the ADP3334’s pins since it will increase
the junction-to-ambient thermal resistance of the package.
2x VIAS, 0.250
35µm PLATING
0.73
0.30
1.80
0.90
2.36
0.50
1.40
1.90
3.36
Figure 6. 3 mm x 3 mm LFCSP Pad Pattern
(Dimensions shown in millimeters)
LFCSP Layout Considerations
The LFCSP package has an exposed die paddle on the bottom,
which efficiently conducts heat to the PCB. In order to achieve
the optimum performance from the LFCSP package, special
consideration must be given to the layout of the PCB. Use the
following layout guidelines for the LFCSP package.
1. The pad pattern is given in Figure 6. The pad dimension
should be followed closely for reliable solder joints while
maintaining reasonable clearances to prevent solder bridging.
2. The thermal pad of the LFCSP package provides a low thermal impedance path (approximately 20°C/W) to the PCB.
Therefore the PCB must be properly designed to effectively
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. See Figure 5 for the recommended via pattern. Note that the via diameter is small to
prevent the solder from flowing through the via and leaving
voids in the thermal pad solder joint.
Note that the thermal pad is attached to the die substrate, so
the thermal planes that the vias attach the package to must
be electrically isolated or connected to V
. Do NOT con-
IN
nect the thermal pad to ground.
REV. B–8–
ADP3334
3. The solder mask opening should be about 120 microns
(4.7 mils) larger than the pad size resulting in a minimum
60 micron (2.4 mils) clearance between the pad and the
solder mask.
4. The paste mask opening is typically designed to match the
pad size used on the peripheral pads of the LFCSP package.
This should provide a reliable solder joint as long as the
stencil thickness is about 0.125 mm.
The paste mask for the thermal pad needs to be designed for
the maximum coverage to effectively remove the heat from the
package. However, due to the presence of thermal vias and the
size of the thermal pad, eliminating voids may not be possible.
5. The recommended paste mask stencil thickness is 0.125 mm.
A laser cut stainless steel stencil with trapezoidal walls should
be used.
A “No Clean” Type 3 solder paste should be used for mounting the LFCSP package. Also, a nitrogen purge during the
reflow process is recommended.
6. The package manufacturer recommends that the reflow
temperature should not exceed 220°C and the time above
liquidus is less than 75 seconds. The preheat ramp should be
3°C/second or lower. The actual temperature profile depends
on the board density and must determined by the assembly
house as to what works best.
Use the following general guidelines when designing printed
circuit boards.
1. Keep the output capacitor as close as possible to the output and ground pins.
2. Keep the input capacitor as close as possible to the input
and ground pins.
3. PC board traces with larger cross sectional areas will remove
more heat from the ADP3334. For optimum heat transfer,
specify thick copper and use wide traces.
4. Use additional copper layers or planes to reduce the
thermal resistance. When connecting to other layers, use
multiple vias if possible.
Shutdown Mode
Applying a TTL high signal to the shutdown (SD) pin or the
input pin will turn the output off. Pulling SD down to 0.4 V or
below or tying it to ground will turn the output on. In shutdown
mode, quiescent current is reduced to much less than 1 µA.
REV. B
–9–
ADP3334
OUTLINE DIMENSIONS
8-Lead Standard Small Outline Package [SOIC]
Narrow Body
(RN-8)
Dimensions shown in millimeters and (inches)
5.00 (0.1968)
4.80 (0.1890)
4.00 (0.1574)
3.80 (0.1497)
0.25 (0.0098)
0.10 (0.0040)
COPLANARITY
0.10
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
85
1.27 (0.0500)
SEATING
PLANE
COMPLIANT TO JEDEC STANDARDS MS-012AA
BSC
6.20 (0.2440)
5.80 (0.2284)
41
1.75 (0.0688)
1.35 (0.0532)
0.51 (0.0201)
0.33 (0.0130)
0.25 (0.0098)
0.19 (0.0075)
0.50 (0.0196)
0.25 (0.0099)
8
0
1.27 (0.0500)
0.41 (0.0160)
8-Lead Frame Chip Scale Package [LFCSP]
Dimensions shown in millimeters
45
3 mm 3 mm Body
(CP-8)
8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
3.00
BSC
85
3.00
BSC
1
PIN 1
0.65 BSC
0.15
0.00
0.38
0.22
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-187AA
4
SEATING
PLANE
4.90
BSC
1.10 MAX
0.23
0.08
8
0
0.80
0.40
PIN 1
INDICATOR
0.90 MAX
0.85 NOM
SEATING
PLANE
12 MAX
3.00
BSC SQ
0.45
TOP
VIEW
0.30
0.23
0.18
DIMENSIONS SHOWN ARE IN MILLIMETERS
2.75
BSC SQ
0.80 MAX
0.65 NOM
0.20 REF
0.05 MAX
0.01 NOM
0.50
BSC
0.60 MAX
0.25
MIN
BOTTOM
VIEW
1.60
1.45
1.30
0.60
0.42
0.24
1
2
PIN 1 INDICATOR
1.50
REF
1.89
1.74
1.59
REV. B–10–
ADP3334
Revision History
Location Page
3/03—Data Sheet changed from REV. A to REV. B.
Edits to Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Edits to Output Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Added text to Output Voltage section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Added Figure 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Edits to Calculating Junction Temperature section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Renumbered Figures 5 and 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1/03—Data Sheet changed from REV. 0 to REV. A.
Added 8-Lead LFCSP and 8-Lead MSOP Packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Universal
Edits to product title . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Edits to FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Edits to APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Edits to GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Removed pin numbers from Figure 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Edits to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Edits to ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Edits to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Added pinouts to PIN CONFIGURATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Added text to Calculating Junction Temperature section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Added LFCSP Layout Considerations section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Added Figure 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Updated 8-Lead SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
REV. B
–11–
C02610–0–3/03(B)
–12–
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