COM-HPC-ALT User’s Guide PICMG COM-HPC R1.0
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4.2 Signal Terminology Descriptions
Definitions of the terms used for signal description tables
Bi-directional Input / Output
Open drain output from the module
Bi-directional signal 3.3V tolerant
Bi-directional signal 5V tolerant
Input or output 3.3V tolerant active in standby state
PCI Express compatible differential signal
Serial ATA specification Revision 2.6 and 3
Low Voltage Differential Signal - 330 mV nominal; 450 mV maximum differential signal
Reference voltage output. May be sourced from a Module power plane.
Pull-down strap. A Module output pin that is either tied to GND or is not connected.
Used to signal Module capabilities to the Carrier Board.
PU (pull-up) resistor on module
PD (pull-down) resistor on module