1
Date: 5/16/04 SPX1580 7A Ultra Dropout Voltage Regulator ©Copyright 2004 Sipex Corporation
SPX1580
DESCRIPTION
FEATURES
■Low Dropout Voltage 540mV at 7A Full Load Current
■Adjustable Ouput Down to 1.25V from ATX Power Supply
■Fixed Output Voltages of 3.3V and 2.5V
■Extremely Tight Load and Line Regulation
■Standard 5-Terminal Low Cost TO-220 and TO-263
■Replacement to Industry Standard LT1580
®
The SPX1580 is a 7A Low Dropout Regulator with extremely low dropout voltage. The adjustable version
requires only two external resistors to set the output voltage. The fixed version has a preset output of 3.3V
or 2.5V and does not require any external resistors. The SPX1580 features a low dropout of 540mV(Typ.)
and offers fast transient response. This device is suitable for Pentium applications requiring 2.5V from 3.3V
ATX power supplies, where a low current input voltage 1V greater than the output voltage is available. With
an external sense pin the load regulation is less than 1mV. This device is an excellent choice for the use
of powering low voltage microprocessors that require a lower dropout, fast transient response to regulate
from 3.3V and 5V supplies. The SPX1580 is also an excellent choice as a post regulator for switching
supplies applications.
The SPX1580 offers protection against over-current faults, reversed input polarity, over temperature
operation and positive and negative transient voltage.
The SPX1580 is offered in a 5 pin TO-220 and TO-263 compatible with industry standard 5-terminal
regualtors. For 5A, 3A and 1.5A ultra low dropout versions refer to SPX1581, SPX1582 and SPX1583 data
sheets respectively.
7A Ultra Dropout Voltage Regulator
Fast Response, Adjustable & Fixed
APPLICATIONS
■3.3V ATX Power Supplies
■3.3V to 2.9V for Portable PENTIUM
TM
Processor
■5V to 3.5V VRE Supply
■High efficiency "Green" Computer Systems
C4
68µF
2.5V
V
OUT
R1
124Ω
R2
124Ω
V
OUT
SENSE
C2
10µF
V
CTRL
C1
33µF
3.3V
V
IN
5V
V
CTRL
SPX1580
5
4
2
3
1
(1) V
CTRL
needed when V
IN
< 5V.
(2) V
OUT
= V
REF
(1+R
2
/R
1
)+I
ADJ
R
2
.
(3) V
REF
is measured across adjust to sense.
ADJ
V
IN
C4
68µF
2.5V
V
OUT
V
OUT
SENSE
C2
10µF
V
CTRL
C1
33µF
3.3V
V
IN
5V
V
CTRL
SPX1580
5
4
2
3
1
(1) V
CTRL
needed when V
IN
< 5V.
GND
V
IN
321
SPX1580
5 Pin TO-220
SENSE
ADJ OR FIXED
V
OUT
V
CNTRL
V
IN
45
123
SPX1580
5 Pin TO-263
SENSE
ADJ OR FIXED
V
OUT
V
CNTRL
V
IN
TYPICAL APPLICATIONS CIRCUITS
Now Available in Lead Free Packaging
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Date: 5/16/04 SPX1580 7A Ultra Dropout Voltage Regulator ©Copyright 2004 Sipex Corporation
Power Dissipation ..................................... Internally Limited
Lead Temp. (Soldering, 10 Seconds) ......................... 300°C
Storage Temperature Range ..................... -65°C to +150°C
Operating Junction Temperature Range
SPX1580 Control Section ............................. 0°C to +125°C
SPX1580 Power Transistor .......................... 0°C to +150°C
Input Supply Voltage ..................................................... 7V
V
CTRL
Input Voltage .................................................... 13.2V
ELECTRICAL CHARACTERISTICS
ABSOLUTE MAXIMUM RATINGS
Electrical characteristics at VOUT = VSENSE, VADJ = 0V, TA = 25ºC, CCTL = CPWR = COUT = 33µF tantalum cap unless otherwise specified.
The ♦ denotes the specifications which apply over the -40°C to 85°C temperature range, unless otherwise specified.
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3
Date: 5/16/04 SPX1580 7A Ultra Dropout Voltage Regulator ©Copyright 2004 Sipex Corporation
The SPX1580 is designed as a high performance
and low cost solution for application requiring a
lower dropout than traditional NPN regulators.
The SPX1580 uses a separate input voltage VCTRL
( VCTRL ≥ VOUT + 1.3V) to minimize the dropout
voltage. This allows the 2.5V power for the load
to come from a 3.3V system supply.
As added benefit this will reduce the heat dissi-
pation*, and lower heatsink and cooling fan cost.
A typical application would use 3.3V for VIN
and 5.0V for VCTRL from a motherboard power
supply to provide a nominal 2.5V output. Using
the sense pin allows Kelvin measure the output,
reducing resistance-associated errors.
The SPX1580 can power the 2.5V core voltage
for microprocessors such as a PentiumPCTM,
P55CTM, AMD5k86TM and K6TM and the IBM
PowerPCTM 603EV and 604EV processors.
CURRENT
LIMIT
AMPLIFIER
THERMAL OVERLOAD
V
REF
VOLTAGE
REGULATION
AMPLIFIER
S.O.A
LIMIT
SENSE
(4) V
CTRL
V
IN
(5)
V
OUT
(3)
SENSE (1)
ADJ (2)
PIN DESCRIPTION
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APPLICATION INFORMATION
Note that TAB is internally connected to Pin 3.
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Date: 5/16/04 SPX1580 7A Ultra Dropout Voltage Regulator ©Copyright 2004 Sipex Corporation
Output Capacitor
An output capacitor for SPX1580 is for circuit
compensation for the device to prevent
oscilliation. The minimum size of the output
capacitor is either a 330µF aluminum electro-
lytic capacitor or 33uF tantalum. Larger capaci-
tor values improve the regulator transient re-
sponse performance and increase surge load
capability. The output capacitor should have an
ESR not more than 0.3Ω.
Adjustable Regulator Design
1.25V reference voltage is being developed be-
tween the SENSE pin and the ADJ pin of the
SPX1580. Adding two external resistors (see fig
1.) will allow setting the output voltage from
1.25V to 6V. R1 is chosen so that this current is
specified minimum load current of 10mA. R2 is
given by the formula: VOUT = VREF (1+ R2/R1)
+ IADJ (R2). The current flowing from the ADJ
pin is typicaly 50uA. This ADJ pin contributes
to the final VOUT but is usually neglected.
Connecting the sense pin to the top of the resis-
tor divider will improve load regualtion.
Lowering Noise
Using the SENSE pin to Kelvin the load will
increase accuracy of the output voltage during
load regulation. For the fixed voltage device,
adding a bypass capacitor from ADJ pin to
ground improves transient response. A 330pF
ceramic capacitor is recommended.
C3
68µF
2.5V
V
OUT
R1
124Ω
R2
124Ω
V
OUT
SENSE
C2
10µF
V
CTRL
C1
33µF
3.3V
V
IN
5V
V
CTRL
SPX1580
5
4
2
3
1
(1) V
CTRL
needed when V
IN
< 5V.
(2) V
OUT
= V
REF
(1+R
2
/R
1
)+I
ADJ
R
2
.
(3) V
REF
is measured across adjust to sense.
ADJ
V
IN
C4
0.033µF
Figure 1. Adjustable Regulator.
APPLICATION INFORMATION
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Date: 5/16/04 SPX1580 7A Ultra Dropout Voltage Regulator ©Copyright 2004 Sipex Corporation
C3
68µF
2.5V
V
OUT
V
OUT
SENSE
C2
10µF
V
CTRL
C1
33µF
3.3V
V
IN
5V
V
CTRL
SPX1580
5
4
2
3
1
(1) V
CTRL
needed when V
IN
< 5V.
GND
V
IN
Figure 2. Typical Fixed Regulator.
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Date: 5/16/04 SPX1580 7A Ultra Dropout Voltage Regulator ©Copyright 2004 Sipex Corporation
PACKAGE: 5 PIN TO-220
.160 - .190
Dimensions in
(inches)
5 PIN TO-220
.015 - .040
A
b
C1
D
E
MIN NOM MAX
e
e1
F
H1
J1
∆P
Q
U
V
L
.014 - .022
.560 - .590
.385 - .415
.385 - .415
.062 - .072
.045 - .055
.234 - .258
.090 - .115
.540 - .560
.146 - .156
.103 - .113
- .30 -
- .24 -
L1
- .250
D
B
SEATING
PLANE
F
A
CHAMFER
OPTIONAL
C1
J1
A
A
E
øP
Q
D
D1
E/2
L
L1
CCDD
b
e1
H1
e
5 PIN TO-220
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Date: 5/16/04 SPX1580 7A Ultra Dropout Voltage Regulator ©Copyright 2004 Sipex Corporation
.160 - .190
0 - .010
Dimensions in (mm)
5 PIN TO-263
JEDEC TO-263
(BB) Variation
.020 - .039
.015 - .029
.070 - .110
-
- -
A
A1
b
c
E
E1
L
L1
L2
MIN NOM MAX
e.067 BSC
.066
-
D1 .270 - -
.380 - .420
.245 -
-
H.575 - .625
.070
L3 .010 BSC
c
WITH PLATING
BASE METAL
(b)
CONTACT AREA
123
45
E
E
L2
5X b
e
4X
(DATUM A)
c2 .045 - .023
c
C2
A
H
SEATING PLANE
D1
L1
(E)
E1
L
0º-8º
L3
5 PIN TO-263
PACKAGE: 5 PIN TO-263
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Date: 5/16/04 SPX1580 7A Ultra Dropout Voltage Regulator ©Copyright 2004 Sipex Corporation
Corporation
ANALOG EXCELLENCE
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the
application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
Sipex Corporation
Headquarters and
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (408) 935-7600
Part Number Operating Temperature Range Package Type
SPX1580U5 ................................................ -40°C to +85°C........................................................ 5 Pin TO-220
SPX1580U5-2.5 .......................................... -40°C to +85°C....................................................... 5 Pin TO-220
SPX1580U5-3.3 .......................................... -40°C to +85°C....................................................... 5 Pin TO-220
SPX1580T5 ................................................ -40°C to +85°C........................................................ 5 Pin TO-263
SPX1580T5/TR .......................................... -40°C to +85°C........................................................ 5 Pin TO-263
SPX1580T5-2.5 .......................................... -40°C to +85°C....................................................... 5 Pin TO-263
SPX1580T5-2.5/TR .................................... -40°C to +85°C....................................................... 5 Pin TO-263
SPX1580T5-3.3 .......................................... -40°C to +85°C....................................................... 5 Pin TO-263
SPX1580T5-3.3/TR .................................... -40°C to +85°C....................................................... 5 Pin TO-263
/TR = Tape and Reel
Pack quantity is 500 for TO-263.
ORDERING INFORMATION
Available in lead free packaging. To order add "-L" suffix to part number.
Example: SPX1580T5-3.3/TR = standard; SPX1580T5-L-3.3/TR = lead free
