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September 2010 Rev. 2.0.0
Exar Corporation www.exar.com
48720 Kato Road, Fremont CA 94538, USA Tel. +1 510 668-7000 – Fax. +1 510 668-7001
GENERAL DESCRIPTION
The SPX1587 is a low power positive-voltage
regulator designed to satisfy moderate power
requirements with a cost effective, small
footprint solution.
This device is an excellent choice for use in
battery-powered applications and portable
computers. The SPX1587 features very low
quiescent current and a low dropout voltage of
1.1V at a full load. As output current
decreases, quiescent current flows into the
load, increasing efficiency. SPX1587 is
available in adjustable or fixed 1.5V, 2.5V,
3.3V and 5.0V output voltages.
The SPX1587 is offered in several 3-pin
surface mount packages: TO-252, TO-220 and
TO-263. An output capacitor of 10μF ceramic
or tantalum provides unconditional stability.
APPLICATIONS
• Desktop PC's Servers
• Powering VGA and Sound Cards
• Adjustable Power Supplies
• Portable Instrumentation
FEATURES
• Guaranteed 3A Output Current
• Three Terminal Adjustable or Fixed
1.5V, 2.5V, 3.3V and 5.0V
• Low Quiescent Current
• Low Dropout Voltage: 1.1V at 3A
• Line Regulation: 0.1%
• Load Regulation: 0.1%
• Stable with 10uF Ceramic Capacitor
• Over Current and Thermal Protection
• Similar to Industry Standard
LT1085/LT1585
• RoHS Compliant Lead Free 3-Pin
TO-220, TO-252 and TO-263 Packages
FUNCTIONAL DIAGRAM
Fig. 1: SPX1587 Functional Diagram (Adjustable version)
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© 2010 Exar Corporation 2/11 Rev. 2.0.0
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation of
the device at these ratings or any other above those
indicated in the operation sections of the specifications
below is not implied. Exposure to absolute maximum
rating conditions for extended periods of time may affect
reliability.
Input Supply Voltage V
IN
.................................... +10.0V
Input to Output Voltage ....................................... +8.8V
Storage Temperature .............................. -65°C to 150°C
Power Dissipation ................................ Internally Limited
Lead Temperature (Soldering, 5 sec) ..................... 260°C
ESD Rating (HBM - Human Body Model) .................... 2kV
OPERATING RATINGS
Junction Temperature Range .................... -40°C to 125°C
Thermal Resistance
TO-220 θ
JC
...................................................... 3°C/W
TO-220 θ
JA
................................................. 29.4°C/W
TO-263 θ
JC
...................................................... 3°C/W
TO-263 θ
JA
................................................. 31.4°C/W
TO-252 θ
JC
...................................................... 6°C/W
TO-252 θ
JA
.................................................... 50°C/W
ELECTRICAL SPECIFICATIONS
Specifications with standard type are for an Operating Ambient Temperature of T
A
= 25°C only; limits applying over the full
Operating Temperature range (-40°C to +85°C) are denoted by a “•”. Minimum and Maximum limits are guaranteed
through test, design, or statistical correlation. Typical values represent the most likely parametric norm at T
A
= 25°C, and
are provided for reference purposes only. Unless otherwise indicated, V
IN
= V
OUT
+ 1.5V, T
A
= 25°C, C
IN
= C
OUT
=10µF,
I
OUT
=10mA.
Parameter Min. Typ. Max. Units Conditions
1.5V Version
Output Voltage
SPX1587A
1.485 1.500 1.515 V I
OUT
=10mA, V
OUT
=3.5V
1.470 1.530 • 10mA≤I
OUT
≤3A, 3.0V≤V
OUT
≤10V
2.5V Version
Output Voltage
SPX1587
2.450 2.500 2.550 V I
OUT
=10mA, V
OUT
=4.5V
2.425 2.575 • 10mA≤I
OUT
≤3A, 4.25V≤I
OUT
≤10V
3.3V Version
Output Voltage
SPX1587A
3.267 3.300 3.333 V I
OUT
=10mA, V
OUT
=5V
3.234 3.366 • 10mA≤I
OUT
≤3A, 4.75V≤V
OUT
≤10V
Output Voltage
SPX1587
3.234 3.300 3.366 V I
OUT
=10mA, V
OUT
=5V
3.201 3.399 • 10mA≤I
OUT
≤3A, 4.75V≤V
OUT
≤10V
5.0V Version
Output Voltage
SPX1587A
4.950 5.000 5.050 V I
OUT
=10mA, V
OUT
=7V
4.900 5.100 • 10mA≤I
OUT
≤3A, 6.50V≤V
OUT
≤10V
All Voltage Options
Reference Voltage
SPX1587A
1.238 1.250 1.262 V I
OUT
=10mA, V
IN
-V
OUT
=2V
1.225 1.275 • 10mA≤I
OUT
≤3A, 1.50V≤V
IN
-V
OUT
≤10V
Reference Voltage
SPX1587
1.225 1.250 1.275 V I
OUT
=10mA, V
IN
-V
OUT
=2V
1.212 1.287 • 10mA≤I
OUT
≤3A, 1.50V≤V
IN
-V
OUT
≤10V
Output Voltage Temperature
Stability – SPX1587A 0.3 %
Output Voltage Temperature
Stability – SPX1587 0.5 %
Line Regulation 0.1 0.2 %
3.0V≤V
IN
≤10V, V
OUT
=1.5V
4.25V≤V
IN
≤10V, V
OUT
=2.5V
4.75V≤V
IN
≤10V, V
OUT
=3.3V
6.50V≤V
IN
≤10V, V
OUT
=5.0V
Load Regulation 0.1 0.3 %
10mA≤I
OUT
≤3A, V
OUT
=1.5V
10mA≤I
OUT
≤3A, V
OUT
=2.5V
10mA≤I
OUT
≤3A, V
OUT
=3.3V
10mA≤I
OUT
≤3A, V
OUT
=5.0V
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© 2010 Exar Corporation 3/11 Rev. 2.0.0
Parameter Min. Typ. Max. Units Conditions
Dropout Voltage (note 2)
1.00
V
I
OUT
=1A
1.05 I
OUT
=2A
1.10 1.2 I
OUT
=3A
Minimum Load Current
(note 4) 4 10 mA
Quiescent Current 4 10 mA
Fixed Voltage Versions
Adjust Pin Current 50 µA
120 µA
•
Current Limit 3.2 5 A
V
IN
-V
OUT
=2V
Thermal Regulation 0.01 0.1 %/W
25°C, 30ms pulse
Ripple Rejection 60 75 dB
F
RIPPLE
=120Hz, V
IN
-V
OUT
=2V, V
RIPPLE
=1V
PP
Long Term Stability 0.03 %
125°C, 1000 hours
RMS Output Noise 0.03 %
% of V
OUT
, 10Hz ≤ f ≤ 10kHz
Note 1: Output temperature coefficient is defined as the worst case voltage change divided by the total temperature range
Note 2: Dropout voltage is defined as the input to output differential at which the output voltage drops 100mV below its
nominal value measured at 1V differential at very low values of programmed output voltage, the minimum input supply
voltage of 2V (2.3V over temperature) must be taken into account.
Note 3: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is
applied. Excluding load or line regulation effect.
Note 4: Adjustable Version Only.
BLOCK DIAGRAM
Fig. 2: SPX1587 Block Diagram
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© 2010 Exar Corporation 4/11 Rev. 2.0.0
PIN ASSIGNMENT
Fig. 3: SPX1587 Pin Assignment
PIN DESCRIPTION
Name Pin Number Description
ADJ/GND 1 Adjustable Voltage Pin or Ground signal for fixed voltage versions.
VOUT 2 Output Voltage
VIN 3 Input Voltage
TAB TAB Tab is connected to VOUT (pin 2) for all packages
ORDERING INFORMATION
Part Number Junction
Temperature Range Marking Package Packing Quantity Note 1
SPX1587T-L
-40°C≤T
J
≤+125°C
Sipex
SPX1587T
YYWWLX
TO263-3
Bulk
Lead Free
SPX1587T-L/TR 500/Tape & Reel
SPX1587T-L-1-5
-40°C≤T
J
≤+125°C
Sipex
SPX1587T
15YYWWLX
TO263-3
Bulk
Lead Free
SPX1587T-L-1-5/TR 500/Tape & Reel
SPX1587T-L-5-0
-40°C≤T
J
≤+125°C
Sipex
SPX1587T
50YYWWLX
TO263-3
Bulk
Lead Free
SPX1587T-L-5-0/TR 500/Tape & Reel
SPX1587U-L-3-3 -40°C≤T
J
≤+125°C
Sipex
SPX1587U
33YYWWLX
TO220-3 Bulk Lead Free
SPX1587U-L-5-0 -40°C≤T
J
≤+125°C
Sipex
SPX1587U
50YYWWLX
TO220-3 Bulk Lead Free
SPX1587AR-L
-40°C≤T
J
≤+125°C
Sipex
SPX1587AR
YYWWLX
TO252-3
Bulk
Lead Free
SPX1587AR-L/TR 2K/Tape & Reel
SPX1587AT-L
-40°C≤T
J
≤+125°C
Sipex
SPX1587AT
YYWWLX
TO263-3
Bulk
Lead Free
SPX1587AT-L/TR 500/Tape & Reel
SPX1587AT-L-2-5
-40°C≤T
J
≤+125°C
Sipex
SPX1587AT
25YYWWLX
TO263-3
Bulk
Lead Free
SPX1587AT-L-2-5/TR 500/Tape & Reel
SPX1587AT-L-3-3
-40°C≤T
J
≤+125°C
Sipex
SPX1587AT
33YYWWLX
TO263-3
Bulk
Lead Free
SPX1587AT-L-3-3/TR 500/Tape & Reel
SPX1587AU-L -40°C≤T
J
≤+125°C
Sipex
SPX1587AU
YYWWLX
TO220-3 Bulk Lead Free
“YY” = Year – “WW” = Work Week – “L” = Lead Free Indicator – “X” = Lot Number; when applicable.
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© 2010 Exar Corporation 5/11 Rev. 2.0.0
TYPICAL PERFORMANCE CHARACTERISTICS
All data taken at V
IN
= V
OUT
+ 1.5V, T
A
= 25°C, C
IN
= C
OUT
=10µF, I
OUT
=10mA unless otherwise specified - Schematic and
BOM from Application Information section of this datasheet.
Fig. 4: Line Regulation for SPX1587U-3-3
I
OUT
=10mA
Fig. 5: V
OUT
versus Temperature
V
IN
=2.5V, I
OUT
=10mA
Fig. 6: V
OUT
versus Temperature
V
IN
=4.0V, I
OUT
=10mA
Fig. 7: V
OUT
versus Temperature
V
IN
=5.0V, I
OUT
=10mA
APPLICATION INFORMATION
OUTPUT CAPACITOR
To ensure the stability of the SPX1587, an
output capacitor of at least 10μF (ceramic or
tantalum) or 22μF (aluminum) is required. The
value may change based on the application
requirements of the output load or
temperature range. The value of ESR can vary
based on the type of capacitor used in the
applications to guarantee stability. The
recommended value for ESR is 0.5Ω or less. A
larger value of output capacitance (up to
100μF) can improve the load transient
response.
SOLDERING METHODS
The SPX1587 die is attached to the heatsink
lead which exits opposite the input, output,
and ground pins.
THERMAL CHARACTERISTICS
The SPX1587 features the internal thermal
limiting to protect the device during overload
conditions. Special care needs to be taken
during continuous load conditions such that
the maximum junction temperature does not
exceed 125°C. Thermal protection is activated
at >179°C and deactivated at <165 °C.
The thermal interaction from other
components in the application can affect the
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© 2010 Exar Corporation 6/11 Rev. 2.0.0
thermal resistance of the SPX1587. The actual
thermal resistance can be determined with
experimentation.
The SPX1587 power dissipation is calculated
as follows:
Maximum Junction Temperature range:
Where θ
JA
is the junction-to-ambient thermal
resistance of the package.
Maximum junction temperature must not
exceed 125°C.
RIPPLE REJECTION
Ripple rejection can be improved by adding a
capacitor between the ADJ pin and ground as
shown in Figure 11. When ADJ pin bypassing
is used, the value of the output capacitor
required increases to its maximum. If the ADJ
pin is not bypassed, the value of the output
capacitor can be lowered to 22μF for an
electrolytic aluminum capacitor or 10μF for a
solid tantalum capacitor (Fig 10).
However the value of the ADJ-bypass
capacitor should be chosen with respect to the
following equation:
1
6.28
Where
C = value of the capacitor in Farads (select an
equal or larger standard value)
F
R
= ripple frequency in Hz
R
1
= value of resistor R1 in Ohms.
If an ADJ-bypass capacitor is used, the
amplitude of the output ripple will be
independent of the output voltage. If an ADJ-
bypass capacitor is not used, the output ripple
will be proportional to the ratio of the output
voltage to the reference voltage:
Where
M = multiplier for the ripple seen when the
ADJ pin is optimally bypassed.
V
REF
=1.25V
Ripple rejection for the adjustable version is
showing in Figure 8.
OUTPUT VOLTAGE
The output of the adjustable regulator can be
set to any voltage between 1.25V and 15V.
The value of V
OUT
can be quickly approximated
using the formula
1.25
Small correction to this formula is required de-
pending on the values of resistors R1 and R2,
since the adjustable pin current (approx 50μA)
flows through R2. When I
ADJ
is taken into
account, the formula becomes
1
Where
V
REF
=1.25V
LAYOUT CONSIDERATIONS
Parasitic line resistance can degrade load
regulation. In order to avoid this, connect R1
directly to V
OUT
as illustrated in Figure 13. For
the same reason, R2 should be connected to
the negative side of the load.
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© 2010 Exar Corporation 7/11 Rev. 2.0.0
Fig. 8: Ripple Rejection
V
IN
=3.3V, V
OUT
=1.8V(adj), I
LOAD
=200mA
Fig. 9: Current Source
Fig. 10: Typical Adjustable Regulator
Fig. 11: Improving Ripple Rejection
Fig. 12: 5V Regulator With Shutdown
Fig. 13: Recommended Connections for Best Results
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© 2010 Exar Corporation 8/11 Rev. 2.0.0
PACKAGE SPECIFICATION
3-PIN TO263
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© 2010 Exar Corporation 9/11 Rev. 2.0.0
3-PIN TO220
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© 2010 Exar Corporation 10/11 Rev. 2.0.0
3-PIN TO252
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© 2010 Exar Corporation 11/11 Rev. 2.0.0
REVISION HISTORY
Revision Date Description
2.0.0 Reformat of datasheet
Added marking information
FOR FURTHER ASSISTANCE
Email: customersupport@exar.com
Exar Technical Documentation: http://www.exar.com/TechDoc/default.aspx?
E
XAR CORPORATION
HEADQUARTERS AND SALES OFFICES
48720 Kato Road
Fremont, CA 94538 – USA
Tel.: +1 (510) 668-7000
Fax: +1 (510) 668-7030
www.exar.com
NOTICE
EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve
design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein,
conveys no license under any patent or other right, and makes no representation that the circuits are free of patent
infringement. Charts and schedules contained here in are only for illustration purposes and may vary depending upon a
user’s specific application. While the information in this publication has been carefully checked; no responsibility, however,
is assumed for inaccuracies.
EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or
malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its
safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in
writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all
such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances.
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
