鈻?/div>
High efficiency "Green" Computer Systems
ADJ OR FIXED
SENSE
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
V
IN
5V
V
CTRL
V
IN
C1
330碌F
V
CTRL
5
SPX1581
4
2
ADJ
C2
10碌F
C3
.033碌F
R2
124鈩?/div>
1
SENSE
R1
124鈩?/div>
C4
2x330碌F
3
V
OUT
2.5V
V
OUT
3.3V
V
IN
5V
V
CTRL
V
IN
C1
330碌F
V
CTRL
5
SPX1581
4
2
GND
C2
10碌F
1
SENSE
3
V
OUT
2.5V
V
OUT
V
CNTRL
V
OUT
V
IN
C4
2x330碌F
(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.
(1) V
CTRL
needed when V
IN
< 5V.
Adjustable Regulator
Typical Fixed Regulator
Date 5/25/04
SPX1581 5A Ultra Low Dropout Voltage Regulator
漏Copyright 2004 Sipex Corporation
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