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
Input/Output, 12mA sink, 6mA source.
IS/O12
Input with Schmitt Trigger/Output, 12mA sink, 6mA source.
O12
Output, 12mA sink, 6mA source.
OD12
Open Drain Output, 12mA sink.
O6
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
Input with Schmitt Trigger/Output, 8mA sink, 4mA source.
OD14
Open Drain Output, 14mA sink.
OP14
Output, 14mA sink, 14mA source.
IOP14
Input/Output, 14mA sink, 14mA source. Backdrive protected.
IS/OP14
Input with Schmitt Trigger/Output, 14mA sink, 14mA source, Backdrive Protected.
IOD16
Input/Output (Open Drain), 16mA sink.
O4
Output, 4mA sink, 2mA source.
I
Input TTL Compatible.
IS
Input with Schmitt Trigger.
PCI_IO
Input/Output. These pins must meet the PCI 3.3V AC and DC Characteristics. (Note 1)
PCI_O
Output. These pins must meet the PCI 3.3V AC and DC Characteristics. (Note 1)
PCI_OD
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)
PCI_ICLK
Clock Input. These pins must meet the PCI 3.3V AC and DC Characteristics and timing. (Note 2)
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:
• 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
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DATASHEET
Rev. 04-17-07