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SIm900A modem VRTC supply is needed or not

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tinkujangid

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I want to set alarm of 5AM and power down the module at 8PM so it is necessary to give power supply VRTC pin ??

if necessary than by applying 3Volt at VRTC or 4.7uF Capacitor.


As i tried by setting alarm of 5AM it automatically turn on at 5AM than why SIMCOM recommending
3Volt at VRTC pin .

what will be worst case scenario if i did not apply voltage.
 

Hi,

i expect the answers are given in the datasheet.
Did you read the datasheet? What does say about VRTC?

Klaus
 

KlausST said:
Hi,

i expect the answers are given in the datasheet.
Did you read the datasheet? What does say about VRTC?

Klaus
Click to expand...

As i used it after alarm set i power down it automatically on.. datasheet says use a capacitor or give a 3 volt ..but i did not use capacitor or 3 volt but still RTC running after power down .
 

Hi,

datasheet says use a capacitor or give a 3 volt ..but i did not use capacitor or 3 volt
Click to expand...
If you don´t do like in the datasheet... it may work, but not reliable.
* So maybe tomorrow it doesn´t work anymore.
* Or maybe with another SIM900 it doesn´t work.
* or maybe with higher or lower temperature it doesn´t work anymore.

It´s on you how you design it. Whether you want it to work "by accident" or you want it to work reliably.


Klaus
 

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