Power Management Signals; Table 21 Module Type Detection - Emerson COM Express Carrier Design Manual

Table 21 Module Type Detection

Figure 29 illustrates a detection circuitry for Type 2 modules. If any module type other than Type 2 is
connected, the PS_ON# signal, which controls the ATX power supply, is not driven low by the module.
Hence, the main power rails of the ATX supply do not come up. The type detection pins of the module
must be pulled up on the carrier board to the 5 V suspend voltage rail.
Figure 29 Module Type 2 Detection Circuitry

16.2 Power Management Signals

COM Express specifies a set of signals to control the system power states such as the power-on and
reset conditions. This enables the system designer to implement a fully ACPI-compliant system
supporting system states from S0 to S5. The minimum hardware requirements for an ACPI-compliant
system are an ATX conforming power supply and a power button. Table 22 provides a short description
of the ACPI-defined system states S0 to S5, including the corresponding power rail state. For more
information about ACPI and the system power states, refer to the Advanced Configuration and Power
Interface Specification, Revision 3.0.
COM Express Carrier Type 2
Design Guide
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