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ICES 673 User Manual
Chapter 5: Power Control
A carrier board design typically consists of three PWR_OK circuits with the
following usage:
1. PWR_OK is connected to the power good signal of an ATX power
supply.
2. PWR_OK is connected to the last voltage regulator in the chain on the
carrier board.
3. PWR_OK is pulled by a 1k resistor to the 3.3V power rail on the carrier
board.
Note: For option 3, please make sure all the carrier board hardware is
powered on and running stably before the 3.3V is up.
B. SUS_S3#/PS_ON#:
The SUS_S3#/PS_ON# (Pin A15 on the A-B connector) signal is an active-low
output. It can turn on the outputs of an ATX power supply. To do so, invert
the signal using the inverter/transistor on the carrier board. The inverter/
transistor can be powered by the standby voltage from the ATX power
supply.
C. PWRBTN#
The PWRBTN# (Pin B12 on the A-B connector) signal is used to connect to
an active-low push button that has a grounded terminal. It is pulled up by
a 10k resistor to the 3VSB. When a connected push button is pressed, the
PWRBTN# will be asserted, turning the power on or off. Please note that this
action may vary depending on the software and BIOS settings.
