ADP3334
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 CO = 1.0 F for Stability
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
FUNCTIONAL BLOCK DIAGRAM
Q1
IN
OUT
ADP3334
THERMAL
PROTECTION
CC
FB
gm
DRIVER
SD
BAND GAP
REF
GND
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 available in three different package options:
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.
1. Excellent thermal capability, space saving 3 mm ⫻ 3 mm LFCSP.
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.
2. Popular low profile MSOP-8.
3. Traditional thermal enhanced SOIC-8.
ADP3334
VIN
IN
OUT
IN
OUT
VOUT
R1
CIN
1F
FB
SD
GND
CNR
COUT
1F
R2
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–SPECIFICATIONS1, 2, 3 (V
IN
= 6.0 V, CIN = COUT = 1.0 F, TA = –40C to +85C, unless otherwise noted.)
Parameter
Symbol
Conditions
Min
OUTPUT
Voltage Accuracy4
VOUT
VIN = VOUT(NOM) + 0.4 V to 11 V
IL = 0.1 mA to 500 mA
TA = 25°C
VIN = VOUT(NOM) + 0.4 V to 11 V
IL = 0.1 mA to 500 mA
TA = 85°C
VIN = VOUT(NOM) + 0.4 V to 11 V
IL = 0.1 mA to 500 mA
TJ = 150°C
VIN = VOUT(NOM) + 0.4 V to 11 V
IL = 0.1 mA
TA = 25°C
IL = 0.1 mA to 500 mA
TA = 25°C
VOUT = 98% of VOUT(NOM)
IL = 500 mA
IL = 300 mA
IL = 100 mA
IL = 1 mA
VIN = VOUT(NOM) + 1 V
f = 10 Hz–100 kHz, CL = 10 µF
IL = 500 mA, CNR = 10 nF
f = 10 Hz–100 kHz, CL = 10 µF
IL = 500 mA, CNR = 0 nF
Line Regulation4
Load Regulation
Dropout Voltage
Peak Load Current
Output Noise
GROUND CURRENT5
In Regulation
VDROP
ILDPK
VNOISE
IGND
In Dropout
IGND
In Shutdown
IGNDSD
SHUTDOWN
Threshold Voltage
SD Input Current
Output Current in Shutdown
VTHSD
ISD
IOSD
Max
Unit
–0.9
+0.9
%
–1.8
+1.8
%
–2.3
+2.3
%
0.04
mV/V
0.04
mV/mA
200
140
60
10
800
27
400
250
140
45
IL = 500 mA
IL = 300 mA
IL = 50 mA
IL = 0.1 mA
VIN = VOUT(NOM) – 100 mV
IL = 0.1 mA
SD = 6 V, VIN = 11 V
LDO OFF
LDO ON
0 £ SD £ 5 V
SD = 2 V, VIN = 11 V
Typ
mV
mV
mV
mV
mA
µV rms
µV rms
4.5
2.6
0.5
90
150
10
6
1.5
130
450
mA
mA
mA
µA
µA
0.9
3
µA
1.2
0.01
0.4
3
5
V
V
µA
µA
2.0
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 OUT(NOM) £ 2.2 V.
5
Ground current includes current through external resistors.
Specifications subject to change without notice.
–2–
REV. B
ADP3334
ABSOLUTE MAXIMUM RATSINGS*
PIN FUNCTION DESCRIPTIONS
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
␪JA 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
Lead Temperature Range (Soldering 6 sec) . . . . . . . . . . 300°C
Mnemonic
Function
GND
SD
Ground Pin.
Shutdown Control. Pulling this pin low
turns on the regulator.
Regulator Input.
IN
*Stresses above those listed under Absolute Maximum Ratings may cause permanent 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.
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.
PIN CONFIGURATIONS
OUT 1
OUT 2
FB 3
8
IN
OUT 1
8
IN
GND 1
8
NC
ADP3334ARM
7
IN
7
IN
SD 2
ADP3334AR
7
FB
TOP VIEW
(Not to Scale)
OUT 2
6
SD
FB 3
6
SD
IN 3
TOP VIEW
(Not to Scale)
6
OUT
5
GND
NC 4
5
GND
IN 4
5
OUT
NC 4
NC = NO CONNECT
ADP3334ACP
TOP VIEW*
NC = NO CONNECT
*PINS UNDERSIDE
NC = NO CONNECT
ORDERING GUIDE
Model
Package
Output Description
ADP3334AR
ADJ
ADP3334ACP
ADJ
ADP3334ARM
ADJ
Package
Option
Standard Small Outline
RN-8
Package (SOIC-8)
Lead Frame Chip
CP-8
Scale Package (LFCSP)
3 mm ⫻ 3 mm Body, 8-Lead
MSOP Package
RM-8
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–
Brand
LLA
LLA
ADP3334–Typical Performance Characteristics
2.202
IL = 0
2.200
OUTPUT VOLTAGE – V
2.200
2.199
150mA
2.198
2.197
300mA
2.196
2.195
500mA
4
6
8
INPUT VOLTAGE – V
2.199
10
2.197
2.196
2.195
0
100
200
300
OUTPUT LOAD – mA
500
IL = 500mA
0.2
0.1
500mA
0
–0.1
GROUND CURRENT – mA
OUTPUT CHANGE – %
0.3
1.0
500mA
–0.2
–50 –25
0
25
50
75 100 125 150
JUNCTION TEMPERATURE – C
500
TPC 4. Ground Current vs.
Load Current
10
12
VIN = 6V
VOUT = 2.2V
6
5
300mA
4
3
2
100mA
1
50mA
0
0
–50 –25
0
25
50
75 100 125 150
JUNCTION TEMPERATURE – C
0
400
4
6
8
INPUT VOLTAGE – V
7
300mA
2.0
2
8
0.4
3.0
0
TPC 3. Ground Current vs.
Supply Voltage
0mA
4.0
GROUND CURRENT – mA
400
0.5
200
300
100
OUTPUT LOAD – mA
40
TPC 2. Output Voltage vs.
Load Current
VIN = 6V
VOUT = 2.2V
IL = 0
60
20
0
5.0
0
80
2.193
12
VOUT = 2.2V
100
2.198
TPC 1. Line Regulation Output
Voltage vs. Supply Voltage
0
IL = 100A
120
2.194
2.194
2
140
VOUT = 2.2V
VIN = 6V
GROUND CURRENT – A
2.201
OUTPUT VOLTAGE – V
2.201
VOUT = 2.2V
TPC 6. Ground Current vs.
Junction Temperature
TPC 5. Output Voltage Variation %
vs. Junction Temperature
200
150
100
VOUT = 2.2V
SD = GND
RL = 4.4
3.0
2.5
3
2 COUT = 1F
2.0
1
1.5
0
1.0
4
VIN – V
INPUT/OUTPUT VOLTAGE – V
DROPOUT VOLTAGE – mV
VOUT = 2.2V
VOUT – V
250
0.5
COUT = 10F
2
VOUT = 2.2V
SD = GND
RL = 4.4
0
0
50
1
0
0
200
300
100
OUTPUT LOAD – mA
400
TPC 7. Dropout Voltage vs.
Output Current
2
3
TIME – s
4
200
400
600
TIME – s
800
500
TPC 8. Power-Up/Power-Down
–4–
TPC 9. Power-Up Response
REV. B
ADP3334
VOUT = 2.2V
RL = 4.4
CL = 1F
2.180
2.170
3.000
40
80
140
TIME – s
VOUT = 2.2V
RL = 4.4
CL = 10F
2.170
3.500
3.000
180
40
2.3
2.2
2.2
2.1
400
VIN = 6V
VOUT = 2.2V
CL = 1F
200
0
200
180
0
2.1
400
600
TIME – s
FULL SHORT
800m
SHORT
0
200
400
600
TIME – s
VIN = 4V
1
0
200
800
TPC 13. Load Transient Response
400
600
TIME – s
2
1F
10F
10F
1
1F
0
200
TPC 14. Short Circuit Current
–30
–40
100
120
CL = 1F
IL = 50A
–50
–60
–70
IL = 500mA WITHOUT
NOISE REDUCTION
100
IL = 500mA WITH
NOISE REDUCTION
80
IL = 0mA WITHOUT
NOISE REDUCTION
60
40
CL = 10F
IL = 50A
–80
100
1k
10k
100k
FREQUENCY – Hz
1M
10M
TPC 16. Power Supply Ripple
Rejection
REV. B
800
10
VOUT = 2.2V
IL = 1mA
CL = 10F
CNR = 10nF
CL = 10F
CNR = 0
1
CL = 1F
CNR = 0
0.1
CL = 1F
CNR = 10nF
0.01
20
–90
10
400
600
TIME – s
TPC 15. Turn Off/On Response
VOUT = 2.0V
CNR = 10nF
140
RMS NOISE – V
CL = 1F
IL = 500mA
CL = 10F
IL = 500mA
0
VOLTAGE NOISE SPECTRAL
DENSITY – V/ Hz
VOUT = 2.2V
VIN = 6V
VOUT = 2.2V
RL = 4.4
2
800
160
–20
VSD – V
VOUT = 2.2V
VIN = 6V
CL = 10F
200
800
TPC 12. Load Transient Response
2
400
IOUT – A
IOUT – mA
2.3
2.2
3
RIPPLE REJECTION – dB
80
140
TIME – s
TPC 11. Line Transient Response
VOUT – V
TPC 10. Line Transient Response
VOUT – V
2.190
2.180
VIN – V
VIN – V
3.500
2.200
IOUT – mA
2.190
2.210
VOUT – V
2.200
VOUT – V
VOUT – V
VOUT – V
2.210
0
0
IL = 0mA WITH NOISE REDUCTION
10
20
30
CL – F
40
TPC 17. RMS Noise vs. CL
(10 Hz to 100 kHz)
–5–
50
0.001
10
100
1k
10k
100k
FREQUENCY – Hz
TPC 18. Output Noise Density
1M
ADP3334
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.
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.
Additional features of the circuit include current limit and thermal shutdown.
APPLICATION INFORMATION
Output Capacitor
OUTPUT
INPUT
Q1
NONINVERTING
WIDEBAND
DRIVER
ATTENUATION
(VBANDG AP / VOUT)
COMPENSATION
CAPACITOR
R3 D1
PTAT
FB
VOS
gm
PTAT
CURRENT
R4
ADP3334
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.
R1
CLOAD
(a)
RLOAD
R2
GND
Input Bypass Capacitor
Figure 2. Functional Block Diagram
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.
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.
Noise Reduction Capacitor
A noise reduction capacitor (CNR) can be placed between the
output and the feedback pin to further reduce the noise by
6 dB 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.
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.
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 CNR increases, the turn-on time
will be delayed. With CNR values of 1 nF, this delay may be
on the order of several milliseconds.
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.
ADP3334
VIN
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
IN
OUT
IN
OUT
VOUT
R1
CIN
1F
FB
SD
GND
CNR
COUT
1F
R2
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.
–6–
REV. B
ADP3334
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.
3.0
2.5
VFB = VOUT
Ê R2 ˆ
¥Á
˜
Ë R1 + R2 ¯
OUTPUT ERROR – %
R1 ¥ R2
(1)
= 50 kW
R1 + R2
Also, for the best accuracy over temperature, the feedback voltage should be set for 1.178 V:
(2)
0
R2 (1% Resistor) (k)
1.5
1.8
2.2
2.7
3.3
5.0
10.0
63.4
76.8
93.1
115.0
140.0
210.0
422.0
232.0
147.0
107.0
88.7
78.7
64.9
56.2
6
VOUT = 3.274 V
(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:
Ê 138.6
ˆ
VOUT = 1.178 V ¥ Á
+ 1˜
Ë 79.5
¯
VOUT = 3.232 V
(6)
Ê 3.232 ˆ
Resistor Divider Error = Á
- 1˜ ¥ 100% = - 2.1%
Ë 3.3
¯
R1 ¥ R2 138.6 ¥ 79.5
=
= 50.51 kW
R1 + R2 138.6 + 79.5
Ê 50.51 ˆ
Error = Á
- 1˜ ¥ 100% = 1.02%
Ë 50
¯
RPARALLEL =
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.
RPARALLEL
(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%.
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.
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.
For example:
VIN = 5 V
VOUT = 3.3 V
R1 = 140 kW, 1%
R2 = 78.7 kW, 1%
REV. B
5
Ê R1 ˆ
VOUT = 1.178 V ¥ Á
+ 1˜
Ë R2
¯
Table I. Feedback Resistor Selection
R1 (1% Resistor) (k)
3
4
Rp ERROR – %
The actual output voltage can be calculated using the following
equation.
(4)
VOUT (V)
2
Figure 4. Output Voltage Error vs.
Parallel Resistance Error
(3)
50 kW
Ê
VFB ˆ
˜
Á1 - V
Ë
OUT ¯
1.0
0
Combining the above equations and solving for R1 and R2 gives
the following formulas:
R2 =
1.5
0.5
where VOUT is the desired output voltage and VFB is the virtual
band gap voltage. Note that VFB does not actually appear at the
FB pin due to loading by the internal PTAT current.
ÊV
ˆ
R1 = 50 kW ¥ Á OUT ˜
V
Ë FB ¯
2.0
–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.
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.
Calculating Junction Temperature
Device power dissipation is calculated as follows:
PD = (VIN - VOUT ) I LOAD + (VIN ) IGND
(8)
where ILOAD and IGND are load current and ground current, VIN
and VOUT are input and output voltages, respectively.
Assuming ILOAD = 400 mA, IGND = 4 mA, VIN = 5.0 V and
VOUT = 2.8 V, device power dissipation is:
PD = (5 - 2.8) 400 mA + 5.0 (4 mA) = 900 mW
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.
(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:
DTJA = 0.900W ¥ 86.6∞C / W = 77.9∞C
2x VIAS, 0.250
35µm PLATING
0.73
0.30
(10)
1.80
0.90
To limit the maximum junction temperature to 150°C, maximum allowable ambient temperature will be:
TAMAX = 150∞C - 77.9∞C / W = 72.1∞C
2.36
0.50
(11)
The maximum power dissipation versus ambient temperature
for each package is shown in Figure 5.
1.40
1.90
3.36
3.5
Figure 6. 3 mm x 3 mm LFCSP Pad Pattern
(Dimensions shown in millimeters)
48C/W LFCSP
POWER DISSIPATION – W
3.0
LFCSP Layout Considerations
2.5
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.
62C/W LFCSP
2.0
86C/W SOIC
1.5
122C/W SOIC
1.0
0.5
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.
158C/W MSOP
220C/W MSOP
0
–20
0
20
40
60
AMBIENT TEMPERATURE – C
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.
80
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.
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 VIN. Do NOT connect the thermal pad to ground.
–8–
REV. B
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.
Use the following general guidelines when designing printed
circuit boards.
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.
2. Keep the input capacitor as close as possible to the input
and ground pins.
1. Keep the output capacitor as close as possible to the output 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.
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.
4. Use additional copper layers or planes to reduce the
thermal resistance. When connecting to other layers, use
multiple vias if possible.
5. The recommended paste mask stencil thickness is 0.125 mm.
A laser cut stainless steel stencil with trapezoidal walls should
be used.
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.
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.
REV. B
–9–
ADP3334
OUTLINE DIMENSIONS
8-Lead Mini Small Outline Package [MSOP]
(RM-8)
8-Lead Standard Small Outline Package [SOIC]
Narrow Body
(RN-8)
Dimensions shown in millimeters
Dimensions shown in millimeters and (inches)
3.00
BSC
5.00 (0.1968)
4.80 (0.1890)
8
4.00 (0.1574)
3.80 (0.1497)
8
5
1
4
5
4.90
BSC
3.00
BSC
6.20 (0.2440)
5.80 (0.2284)
1
4
PIN 1
1.27 (0.0500)
BSC
0.25 (0.0098)
0.10 (0.0040)
COPLANARITY
SEATING
0.10
PLANE
0.50 (0.0196)
45
0.25 (0.0099)
1.75 (0.0688)
1.35 (0.0532)
0.65 BSC
1.10 MAX
0.15
0.00
8
0.25 (0.0098) 0 1.27 (0.0500)
0.41 (0.0160)
0.19 (0.0075)
0.51 (0.0201)
0.33 (0.0130)
0.38
0.22
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MS-012AA
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
0.23
0.08
8
0
0.80
0.40
SEATING
PLANE
COMPLIANT TO JEDEC STANDARDS MO-187AA
8-Lead Frame Chip Scale Package [LFCSP]
3 mm 3 mm Body
(CP-8)
Dimensions shown in millimeters
3.00
BSC SQ
0.60
0.42
0.24
0.60 MAX
PIN 1 INDICATOR
0.45
PIN 1
INDICATOR
2
TOP
VIEW
2.75
BSC SQ
0.50
BSC
0.90 MAX
0.85 NOM
0.05 MAX
0.01 NOM
0.30
0.23
0.18
BOTTOM
VIEW
1.50
REF
1.89
1.74
1.59
0.25
MIN
0.80 MAX
0.65 NOM
12 MAX
SEATING
PLANE
1
1.60
1.45
1.30
0.20 REF
DIMENSIONS SHOWN ARE IN MILLIMETERS
–10–
REV. B
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–
–12–
C02610–0–3/03(B)
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