SIRETTA ZETA- P Series, Руководство по оборудованию

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41
ZETA-xxP Series
Hardware Manual
rev D
Download Latest Edition
Considerations when manually powering the ZETA-xxP on and off
The PWRON_IN and PWROFF_IN signals requires a positive “edge” (a “sharp” signal
transition from low to high) to turn the modem on. This transition should be a rising
signal from 0V (GND) up to Vcc (max 42V), or at least a large fraction of that voltage
range (>0.5V). Very slow transitions (significantly slower than many milliseconds) or
very small transitions (e.g. only a few millivolts instead of 0V to 0.5V) will not turn on
the modem (since they are not considered to be a “positive edge”).
Although this will not be an issue in almost all typical applications of the modem,
under the following condition special design care has to be taken:
» Large capacitors in your power supply which will lead to slow leading and falling
edges
The case above might prevent the modem from recognizing the power-up signal.
This is no failure of the modem itself, the same would apply to almost any electronic
device that provides a separate “power-on” or “reset” signal.
If you are in doubt, please use the following recommendations:
» Use the Vcc power supply signal from the main supply to test the power on signal
function.
» Make sure that your signal and system design adheres to the recommendations
mentioned above
» Consult our support team and we will be more than happy to assist you.
Disaster recovery power down reset procedure
The ZETA-xxP modems have a special power down reset function for disaster
recovery.
In the event of the standard power down functions failing using the PWROFF_IN pin
or the modem becoming unresponsive then you can apply a modem reset using the
RESET_IN pin. When this pin is connected to logic high (0.5-41V) for >0.5 seconds
the modem will be reset.
Alternatively power can be removed completely from the modem. Wait for a minimum
of 10 seconds and then apply mains power to put the modem in to the startup state.
NOTE - Powering down the modem without following the correct procedure using the
shutdown command or the hardware PWROFF_IN pin can result in improper functioning of the
modem. It will also not detach safely from the Cellular network and may cause the terminal to
become blacklisted.