ADLINK Technology COM Express cExpress-BT2, User Manual

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Pinouts and Signal Descriptions
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