ST1534A
500mA SMART LDO
s
s
s
s
s
s
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GLITCH FREE TRANSITION BETWEEN
INPUT SOURCES
INTERNAL LOGIC SELECTS INPUT
SOURCE
GATE DRIVE FOR EXTERNAL PMOS
BYPASS SWITCH
5V DETECTOR WITH HYSTERESIS
1% 3.3V REGULATED OUTPUT VOLTAGE
500mA GUARANTEED OUTPUT CURRENT
OPERATING TEMPERATURE RANGE
FROM 0擄C TO 85擄C
AVAILABLE IN P
2
PAK PACKAGE
PPAK AND SO-8 PACKAGES CAN BE
AVAILABLE ON REQUEST
P
2
PAK
PPAK
SO-8
APPLICATIONS
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NETWORK INTERFACE CARDS
PCMCIA/PCI INTERFACE CARDS
DESKTOP COMPUTERS
POWER SUPPLY WITH MULTIPLE INPUT
SOURCES
DESCRIPTION
The ST1534A is intended for application such as
power managed PCI and network interface cards
(NICs), where operations from 3.3V VAUX supply
SCHEMATIC DIAGRAM
V
IN
may be required when the 5V supply has been
shut down.
During regular operation, 3.3V power for the PCI
card is provided by the internal LDO regulator,
generated from 5V supply. When the 5V V
AUX
is
available, the IC connects this supply directly to its
output using an external P-Channel FET. This
ensures an uninterrupted 3.3V out even if VIN falls
out of specification.
When both supplies are available simultaneously,
the drive pin DR will be pulled high, turning off the
PMOS switch.
The device is available in the popular 5 leads
P
2
PAK and PPAK
+
5V Detect
DR
Rpull_down
-
V
IN
Reference
+
-
Error
Amp
V
OUT
GND
April 2003
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