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2017
congatec
AG
QA50m10
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PWRBTN#
When using ATX-style power supplies PWRBTN# (pin 20) is used to connect to a momentary-contact, active-low debounced push-button input
while the other terminal on the push-button must be connected to ground. This signal is internally pulled up to 3.3V_SB using a 10k resistor.
When PWRBTN# is asserted, it indicates that an operator wants to turn the power on or off. The response to this signal from the system may
vary as a result of modifications made in BIOS settings or by system software.
Power Supply Implementation Guidelines
5V input power is the sole operational power source for the conga-QA5. The remaining necessary voltages are internally generated on the
module using onboard voltage regulators. A carrier board designer should be aware of the following important information when designing a
power supply for a conga-QA5 application:
•
It has also been noticed that on some occasions, problems occur when using a 5V power supply that produces non monotonic voltage
when powered up. The problem is that some internal circuits on the module (e.g. clock-generator chips) will generate their own reset signals
when the supply voltage exceeds a certain voltage threshold. A voltage dip after passing this threshold may lead to these circuits becoming
confused resulting in a malfunction. It must be mentioned that this problem is quite rare but has been observed in some mobile power
supply applications. The best way to ensure that this problem is not encountered is to observe the power supply rise waveform through
the use of an oscilloscope to determine if the rise is indeed monotonic and does not have any dips. This should be done during the power
supply qualification phase therefore ensuring that the above mentioned problem does not arise in the application. For more information
about this issue visit www.formfactors.org and view page 25 figure 7 of the document “ATX12V Power Supply Design Guide V2.2”.
Inrush and Maximum Current Peaks on VCC_5V_SB and VCC
The inrush current on the conga-QA5 VCC_5V_SB power rail can go up as high as 7.10A and as high as 16.4A on the conga-QA5 VCC power
rail within a short time (approx 100µs) and with a voltage rise time of 100µs. Sufficient decoupling capacitance must be implemented to ensure
proper power-up sequencing.
5.13
Power Management
The conga-QA5 complies with the Advanced Configuration and Power Interface Specification Revision 5.0.
5.14
SMBus
The SMBus is provided by the congatec board controller. The bus is powered by standby 3.3V and has 2.2k ohm pull-ups resistors on the CLK
and DATA signals. The ALERT# signal has 10K-ohm pull-up resistor. Optionally, the SMBus can be connected to the SoC SMBus via an isolation
switch controlled through BIOS.
