Kontron COMe Starterkit Eval T2 - Manual (Page 162)

Power and Reset
3.2.5. Power Button
The COM Express PWRBTN# input may be used by Carrier Board hardware to implement ATX
style power control. A schematic example of how to do this is given in 3.4.1 'ATX Power Supply'
on page 164 below. The COM Express PWRBTN# input is typically de-bounced by the Module
chipset.
The behavior of the system after a power failure depends on the Module chipset capabilities and
on the Module vendor's hardware and BIOS implementation. With most Modules, the following
behaviors may be set by RTC chipset register settings:
Table 54: Power Button States
State Description
Always On No Power Button press needed
Chipset de-asserts SUS_S5#, SUS_S4# and SUS_S3# after Suspend rail to chipset is
stable
Wait For Power Button
Press Chipset remains in Suspend state until power button press is received
Last State If unit was “on” when power was removed, then unit returns to “on” state when power is
restored
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