LPC47M182 SMSC Corporation, LPC47M182 Datasheet - Page 138

• Manufacturer Part Number: LPC47M182
• Description: ADVANCED I/O CONTROLLER WITH MOTHERBOARD GLUE LOGIC
• Manufacturer: SMSC Corporation

7.31
7.31.1 Reference Pins
7.31.2 5V Main Reference Generation
Note:
Revision 1.8 SMSC/Non-SMSC Register Sets (02-24-05)
REF5V
REF5V_STBY
NAME
Power Generation (5V)
O
See DC characteristics see the “Electrical Characteristics” section.
REF5V is used to help power-up various system components’ 5V tolerant buffers. This signal is used to
guarantee there are no power sequencing requirements at each particular system component.
REF5V is powered by VCC when VCC5V < VCC.
Upon motherboard power-up, REF5V is an analog output signal that tracks either VCC or VCC5V (through
an external pull-up resistor), whichever is greater in amplitude. REF5V becomes a high impedance input
while tracking the VCC power supply.
the maximum voltage drop across the diode is 350mV.
AN
: Analog Output, 5V level.
VCC (3.3V)
AO
AO
BUFFER
Table 7.24 – Reference Generation Pins
MAIN SUPPLY
VCC5V < VCC
VCC5V > VCC
3.3mA
3.3mA
CURRENT
MAX OUT
Figure 7.8 – REF5V Circuit
DATASHEET
Table 7.25 – REF5V
VCC
VTR
SMSC I/O
138
Protection
Backdrive
POWER
WELL
REF5V
VCC
Hi-Z
5V Reference Output
Highest System Standby Voltage
Advanced I/O Controller with Motherboard GLUE Logic
REF5V
DESCRIPTION
VCC5V
1k
SMSC LPC47M182
Datasheet