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Dual Power Systems
DESCRIPTION
The SP6231 is a 500mA, 3.3V LDO with an integrated auxiliary voltage input switch. During
normal operation, the SP6231 acts as a standard LDO with an output voltage of 3.3V delivering
up to 500mA. When the 5V input drops below 4.4V, the 3.3V, V
AUX
input is switched to the output
through an internal PFET, maintaining a constant 鈥済litch free鈥?output voltage.
The SP6231 is ideally suited for NIC cards and portable battery powered equipment. When a
desktop computer reverts to sleep mode, its 5V bus is removed, leaving only the 3.3V bus. The
SP6231鈥檚 auxiliary output passes the 3.3V bus through, keeping the NIC card available for any
Wake-On-LAN command. In battery powered applications, the SP6231 draws power from any
available 5V USB connection and reverts to battery power when the USB power is removed.
TYPICAL APPLICATION CIRCUIT
+5V USB
C1
2.2碌F
+3.3V
AUX
C2
2.2碌F
GND
GND
V
AUX
OUT
C3
10碌F
GND
V
OUT
3.3V
@ 500mA
V
IN
SP6231
V
SENSE
Date: 5/25/04
SP6231 500mA, 3.3V Linear Regulator
漏 Copyright 2004 Sipex Corporation
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