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29
ZETA-NLP Series
LTE Cat M1/NB IoT/GSM Ultra Low Power Modem
Considerations when manually powering the ZETA-NLP on and off
ThePWRON_INandPWROFF_INsignalsrequiresapositive“edge”(a“sharp”signal
transitionfromlowtohigh)toturnthemodemon.Thistransitionshouldbearising
signalfrom0V(GND)uptoVcc(max42V),oratleastalargefractionofthatvoltage
range(>0.5V).Veryslowtransitions(significantlyslowerthanmanymilliseconds)or
verysmalltransitions(e.g.onlyafewmillivoltsinsteadof0Vto0.5V)willnotturnon
themodem(sincetheyarenotconsideredtobea“positiveedge”).
Althoughthiswillnotbeanissueinalmostalltypicalapplicationsofthemodem,
underthefollowingconditionspecialdesigncarehastobetaken:
»
Largecapacitorsinyourpowersupplywhichwillleadtoslowleadingandfalling
edges
Thecaseabovemightpreventthemodemfromrecognizingthepower-upsignal.
Thisisnofailureofthemodemitself,thesamewouldapplytoalmostanyelectronic
devicethatprovidesaseparate“power-on”or“reset”signal.
Ifyouareindoubt,pleaseusethefollowingrecommendations:
»
UsetheVccpowersupplysignalfromthemainsupplytotestthepoweronsignal
function.
»
Makesurethatyoursignalandsystemdesignadherestotherecommendations
mentionedabove
»
Consultoursupportteamandwewillbemorethanhappytoassistyou.
Disaster recovery power down reset procedure
TheZETA-NLPmodemshaveaspecialpowerdownresetfunctionfordisasterrecov
-
ery.
IntheeventofthestandardpowerdownfunctionsfailingusingthePWROFF_INpin
orthemodembecomingunresponsivethenyoucanapplyamodemresetusingthe
RESET_INpin.Whenthispinisconnectedtologichigh(0.5-41V)for>0.5seconds
themodemwillbereset.
Alternativelypowercanberemovedcompletelyfromthemodem.Waitforaminimum
of10secondsandthenapplymainspowertoputthemodemintothestartupstate.
NOTE
-Poweringdownthethemodemwithoutfollowingthecorrectprocedureusingthe
shutdowncommandorthehardwarePWROFF_INpincanresultinimproperfunctioningofthe
modem.ItwillalsonotdetachsafelyfromtheCellularnetworkandmaycausetheterminalto
becomeblacklisted.