rtd cpuModules CMA24BT, User Manual

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70 CMA24BT cpuModule BDM-610000087 Rev A
AT vs. ATX Power Supplies
Both AT and ATX power supplies may be used with the CMA24BT cpuModule, however AT power
supplies do not provide any standby power to the cpuModule. When an AT power supply is used to power
the system, low power modes that require a standby power to wake the system will not be fully supported.
ATX power supplies do provide a standby power, thus allowing the system to utilize all low power modes
supported by the hardware. When an ATX supply is used to power the cpuModule, lower power modes can
be achieved. During these low power modes, the standby power from the ATX power supply provides
power to a small circuit on the CPU, which is used to watch for a system wake event.
ATX Power Supply Signals
The PCIe/104 Type 2 Bus connectors ( CN1 & CN2 ) provide two ATX style signals., +5V Standby and
PSON#. The +5V Standby rail is used to power certain parts of the cpuModule when the main power supply
is turned off, i.e. during Suspend-to-RAM (S3), Hibernate (S4), or Soft-Off (S5) power modes. The PSON#
signal is an active low open-drain output that signals the power supply to turn on. Use of these signals allows
the power consumption to drop to below 1W during standby modes, and still enable any of the wake events.
Reducing Power Consumption
In addition to the CPU’s low power modes, power consumption can further be reduced by making some
modifications to the BIOS setup. When the following features are disabled in the BIOS, the CPU’s power
consumption will decrease:
•
Ethernet
•
USB Ports
•
SATA Controller
•
Serial Ports
•
Multi-Color LED