Signal Description Terminology - ADLINK Technology COM Express Express-BL User Manual

3.2.

Signal Description Terminology

The following terms are used in the COM Express AB/CD Signal Descriptions below.
I
O
I/O
OD
I 3.3V
I 5V
O 3.3V
O 5V
I/O 3.3V
I/O 5V
I/O 3.3Vsb
P
REF
PDS
PU
PD
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Input to the Module
Output from the Module
Bi-directional input/output signal
Open drain output
Input 3.3V tolerant
Input 5V tolerant
Output 3.3V signal level
Output 5V signal level
Bi-directional signal 3.3V tolerant
Bi-directional signal 5V tolerant
Input 3.3V tolerant active in standby state
Power Input/Output
Reference voltage output that may be sourced from a module power plane.
Pull-down strap. This is an output pin on the module that is either tied to GND or not connected.
The signal is used to indicate the PICMG module type to the Carrier Board.
ADLINK implemented pull-up resistor on module
ADLINK implemented pull-down resistor on module