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ADP3304 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer ADP3304
Beschreibung High Accuracy anyCAP 100 mA Low Dropout Linear Regulator
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 8 Seiten
ADP3304 Datasheet, Funktion
a
High Accuracy anyCAP™*
100 mA Low Dropout Linear Regulator
ADP3301
FEATURES
High Accuracy (Over Line and Load Regulations
at +25؇C): ؎0.8%
Ultralow Dropout Voltage: 100 mV Typical @ 100 mA
Requires Only CO = 0.47 F for Stability
anyCAP™* = Stable with All Types of Capacitors
Current and Thermal Limiting
Low Noise
Dropout Detector
Low Shutdown Current: 1 A
Several Fixed Voltage Options
3.0 V to 12 V Supply Range
–20؇C to +85؇C Ambient Temperature Range
Thermally Enhanced SO-8 Package
Excellent Line and Load Regulations
APPLICATIONS
Cellular Telephones
Notebook, Palmtop Computers
Battery Powered Systems
Portable Instruments
Post Regulator for Switching Supplies
Bar Code Scanners
GENERAL DESCRIPTION
The ADP3301 is a member of the ADP330x family of precision
low dropout anyCAP™* voltage regulators. The ADP3301
stands out from the conventional LDOs with a novel architec-
ture, an enhanced process and a new package. Its patented
design includes a noninverting wideband driver and a stage that
permits the use of an internal “pole splitting” capacitor to
stabilize the feedback loop with a single output capacitor as
small as 0.47 µF. This device is stable with any type of capacitor
regardless of its ESR (Equivalent Serial Resistance) value,
including ceramic types (MLCC) for space restricted applica-
tions. The ADP3301 achieves exceptional accuracy of ± 0.8% at
room temperature and ± 1.4% overall accuracy over tempera-
ture, line and load regulations. The dropout voltage of the
ADP3301 is only 100 mV (typical) at 100 mA.
In addition to the new architecture and process, ADI’s new
proprietary thermally enhanced package (Thermal Coastline)
can handle 1 W of power dissipation without external heat sink
or large copper surface on the PC board. This keeps PC board
real estate to a minimum and makes the ADP3301 very
attractive for use in portable equipment.
*anyCAP is a trademark of Analog Devices Inc.
FUNCTIONAL BLOCK DIAGRAM
IN
ERR
SD
Q2
Q1
THERMAL
PROTECTION
DRIVER
GND
ADP3301
CC
Gm
BANDGAP
REF
OUT
R1
R2
The ADP3301 operates with a wide input voltage range from
3 V to 12 V and delivers a load current in excess of 100 mA. It
features an error flag that signals when the device is about to
lose regulation or when the short circuit or thermal overload
protection is activated. Other features include shutdown and
optional noise reduction capabilities. The ADP330x anyCAP™*
LDO family offers a wide range of output voltages and output
current levels from 50 mA to 300 mA:
ADP3300 (50 mA, SOT-23)
ADP3302 (100 mA, Dual Output)
ADP3304 (100 mA, Dual Output with Separate Grounds)
ADP3303 (200 mA)
ADP3306 (300 mA)
VIN
C1
0.47µF
NR 3
ADP3301-5.0
7
IN
8
1
OUT
2
ERR 6
5
ON
OFF
4
GND
R1
330k
EOUT
VOUT = +5V
C2
0.47µF
Figure 1. Typical Application Circuit
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, nor for any infringements of patents or other rights of third parties
which 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: 617/329-4700 World Wide Web Site: http://www.analog.com
Fax: 617/326-8703
© Analog Devices, Inc., 1997






ADP3304 Datasheet, Funktion
ADP3301
APPLICATION INFORMATION
anyCAP™*
The ADP3301 is very easy to use. The only external component
required for stability is a small 0.47 µF bypass capacitor on the
output. Unlike the conventional LDO designs, the ADP3301 is
stable with virtually any type of capacitors (anyCAP™*) indepen-
dent of the capacitor’s ESR (Effective Series Resistance) value.
In a typical application, if the shutdown feature is not used, the
shutdown pin (Pin 5) should be tied to the input pin. Pins 7
and 8 must be tied together, as well as Pins 1 and 2, for proper
operation.
Capacitor Selection
Output Capacitors: as with any micropower device, output
transient response is a function of the output capacitance. The
ADP3301 is stable with a wide range of capacitor values, types
and ESR (anyCAP™*). A capacitor as low as 0.47 µF is all that
is needed for stability. However, larger capacitors can be used if
high output current surges are anticipated. The ADP3301 is
stable with extremely low ESR capacitors (ESR 0), such as
multilayer ceramic capacitors (MLCC) or OSCON.
Input Bypass Capacitor: an input bypass capacitor is not
required; however, for applications where the input source is
high impedance or far from the input pins, a bypass capacitor is
recommended. Connecting a 0.47 µF capacitor from the input
pins (Pins 7 and 8) to ground reduces the circuit’s sensitivity to
PC board layout. If a bigger output capacitor is used, the input
capacitor should be 1 µF minimum.
Low ESR capacitors offer better performance on a noisy supply;
however, for less demanding requirements a standard tantalum
or aluminum electrolythic capacitor is adequate.
Noise Reduction
A noise reduction capacitor (CNR) can be used to further reduce
the noise by 6 dB–10 dB (Figure 20). Low leakage capacitors in
the 10 nF–100 nF range provide the best performance. Since
the noise reduction pin (NR) 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. Long PC
board traces are not recommended.
VIN
C1 +
1µF
NR 3
ADP3301-5.0
7
IN
8
1
OUT
2
ERR 6
5
ON
OFF
4
CNR
10nF
R1
330k
+
EOUT
VOUT = 5V
C2
10µF
SD GND
Figure 20. Noise Reduction Circuit
Thermal Overload Protection
The ADP3301 is protected against damage due to 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
high power dissipation) where die temperature starts to rise
above 165°C, the output current is reduced until die tempera-
ture has dropped to a safe level. Output current is restored when
the die temperature is reduced.
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 125°C.
Calculating Junction Temperature
Device power dissipation is calculated as follows :
PD = (VIN – VOUT) ILOAD + (VIN) IGND
Where ILOAD and IGND are load current and ground current, VIN
and VOUT are input and output voltages respectively.
Assuming ILOAD = 100 mA, IGND = 2 mA, VIN = 9 V and
VOUT = 5.0 V, device power dissipation is:
PD = (9 V – 5 V) 100 mA + (9 V) 2 mA = 418 mW
The proprietary package used in ADP3301 has a thermal
resistance of 96°C/W, significantly lower than a standard
8-pin SOIC package at 170°C/W.
Junction temperature above ambient temperature will be
approximately equal to :
0.418 W × 96°C/W = 40.1°C
To limit the maximum junction temperature to 125°C, maxi-
mum ambient temperature must be lower than:
TA(MAX) = 125°C – 40.1°C = 84.9°C
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. However, to make the improvement
meaningful, a significant copper area on the PCB has to be
attached to these fused pins.
The ADP3301’s patented thermal coastline lead frame design
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 96°C/W thermal
resistance for an SO-8 package, without any special board
layout requirements, relying on the normal traces connected to
the leads. The thermal resistance can be decreased by approxi-
mately an additional 10% by attaching a few square cm of
copper area to the VIN pin of the ADP3301 package.
–6– REV. 0

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