SPX1581 Datasheet, PDF (1/7 Pages) Sipex Corporation – 5A Ultra Low Dropout Voltage Regulator Fast Response, Adjustable & Fixed

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SPX1581
5A Ultra Low Dropout Voltage Regulator
Fast Response, Adjustable & Fixed
FEATURES
■ Low Dropout Voltage 500mV at 5A Full Load Current
■ Adjustable Ouput Down to 1.2V from ATX Power Supply
■ Fixed Output Voltages of 3.3V, 2.8V and 2.5V
■ Extremely Tight Load and Line Regulation
■ Standard 5-Terminal Low Cost TO-220 and TO-263
SPX1581
5 Pin TO-263
1 2345
SPX1581
5 Pin TO-220
123 45
APPLICATIONS
■ 3.3V to 2.8V ATX Power Supplies
■ 3.3V to 2.9V for Portable PENTIUM^TM Processor
■ 5V to 3.5V VRE Supply
■ High efficiency "Green" Computer Systems
Now Available in Lead Free Packaging
DESCRIPTION
The SPX1581 is a 5A 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, 2.8V or 2.5V and does
not require any external resistors. The SPX1581 features a low dropout of 400mV(Typ.) and offers fast transient
response. This device is suitable for Pentium applications requiring 2.8V, 2.5V from 3.3V ATX power supplies, where
a low current input voltage 1V greater than the output voltage is needed. 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 SPX1581 is also an excellent choice
as a post regulator for switching supplies applications.
The SPX1581 offers protection against over-current faults, reversed input polarity, over temperature operation and
positive and negative transient voltage.
The SPX1581 is offered in a 5 pin TO-220 and TO-263 compatible with industry standard 5-terminal regulators. For 7A,
3A and 1.5A ultra low dropout versions refer to SPX1580, SPX1582 and SPX1583 data sheets respectively.
TYPICAL APPLICATIONS CIRCUIT
3.3V
VIN
5V
VCTRL
VIN
5
3
C1
SPX1581
330µF
4
1
VCTRL
2
ADJ
C2
10µF
VOUT
SENSE
C3
.033µF
R1
124Ω
R2
124Ω
2.5V
VOUT
C4
2x330µF
3.3V
VIN
5V
VCTRL
VIN
5
VOUT
3
C1
SPX1581
330µF
4
1
VCTRL
2
SENSE
C2
10µF
GND
2.5V
VOUT
C4
2x330µF
(1) VCTRL needed when VIN < 5V.
(2) VOUT = VREF (1+R2/R1)+IADJ R2.
(3) VREF is measured across adjust to sense.
(1) VCTRL needed when VIN < 5V.
Adjustable Regulator
Typical Fixed Regulator
Date 5/25/04
SPX1581 5A Ultra Low Dropout Voltage Regulator
1
©Copyright 2004 Sipex Corporation