Note 12: The TXD1 pin defaults to tristate following a VTR POR since the activate bit is ‘0’, which means Serial Port
1 is in the inactive state.
Buffer Type Descriptions
Note: The buffer type values are specified at VCC=3.3V
IO12
IS/O12
O12
Input/Output, 12mA sink, 6mA source.
Input with Schmitt Trigger/Output, 12mA sink, 6mA source.
Output, 12mA sink, 6mA source.
OD12
O6
Open Drain Output, 12mA sink.
Output, 6mA sink, 3mA source.
O8
Output, 8mA sink, 4mA source.
OD8
Open Drain Output, 8mA sink.
IO8
Input/Output, 8mA sink, 4mA source.
IS/O8
OD14
OP14
IOP14
IS/OP14
IOD16
O4
Input with Schmitt Trigger/Output, 8mA sink, 4mA source.
Open Drain Output, 14mA sink.
Output, 14mA sink, 14mA source.
Input/Output, 14mA sink, 14mA source. Backdrive protected.
Input with Schmitt Trigger/Output, 14mA sink, 14mA source, Backdrive Protected.
Input/Output (Open Drain), 16mA sink.
Output, 4mA sink, 2mA source.
I
Input TTL Compatible.
IS
Input with Schmitt Trigger.
PCI_IO
PCI_O
PCI_OD
Input/Output. These pins must meet the PCI 3.3V AC and DC Characteristics. (Note 1)
Output. These pins must meet the PCI 3.3V AC and DC Characteristics. (Note 1)
Open Drain Output. These pins must meet the PCI 3.3V AC and DC Characteristics.
(Note 1)
PCI_I
Input. These pins must meet the PCI 3.3V AC and DC Characteristics. (Note 1)
Clock Input. These pins must meet the PCI 3.3V AC and DC Characteristics and timing. (Note 2)
PCI_ICLK
Note 1. See the PCI Local Bus Specification, Revision 2.1, Section 4.2.2.
Note 2. See the PCI Local Bus Specification, Revision 2.1, Section 4.2.2. and 4.2.3.
Pins That Require External Pullup Resistors
The following pins require external pullup resistors:
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KDAT
KCLK
MDAT
MCLK
GP36/KBDRST if KBDRST function is used
GP37/A20M if A20M function is used
GP20/P17 If P17 function is used
GP21/P16 if P16 function is used
GP22/P12 if P12 function is used
GP27/nIO_SMI if nIO_SMI function is used as Open Drain Output
GP42/nIO_PME if nIO_PME function is used as Open Drain Output
SER_IRQ
GP40/DRVDEN0 if DRVDEN0 function is used as Open Drain
GP41/DRVDEN1 if DRVDEN1 function is used as Open Drain
nMTR0 if used as Open Drain Output
nDS0 if used as Open Drain Output
nDIR if used as Open Drain Output
nSTEP if used as Open Drain Output
nWDATA if used as Open Drain Output
nWGATE if used as Open Drain Output
nHDSEL if used as Open Drain Output
nINDEX
nTRK0
nWRTPRT
nRDATA
nDSKCHG
GP50-GP57 if the IRQx functions are used
SMSC LPC47B27x
- 13 -
Rev. 08-10-04
DATASHEET
SMSC [ SMSC CORPORATION ]
