Express-HLE
Page 15
3.2
Signal Description Terminology
The following terms are used in the COM Express AB/CD Signal Descriptions below.
I
Input
to
the
Module
O
Output
from
the
Module
I/O
Bi-directional input / output signal
OD Open
drain
output
I 3.3V
Input 3.3V tolerant
I 5V
Input 5V tolerant
O 3.3V
Output 3.3V signal level
O 5V
Output 5V signal level
I/O 3.3V
Bi-directional signal 3.3V tolerant
I/O 5V
Bi-directional signal 5V tolerant
I/O 3.3Vsb Input 3.3V tolerant active in standby state
P
Power
Input/Output
REF
Reference voltage output that may be sourced from a module power plane.
PDS
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.
PU
ADLINK implemented pull-up resistor on module
PD
ADLINK implemented pull-down resistor on module
