SIM800L Power Shortage, Need Help On Power Source Design

Hi and good evening.

I bought a SIM800L board from ebay. I have googled and some got not much info on power source guideline for this module. I am able to power it up using direct connection to step-down voltage regulator 3A (MP1584EN), also bought from ebay. The MP1584EN is connected to 12V 2A adapter.

But still, the SIM800L module having like power shortage. When I try sending AT commands related to SIM access, such as AT+CMGR=1 (for example), the module will restart itself.

Any guidance on what should I do?

A few points...

The SIMCOM 800 & 900 2G GSM/EGSM series will be irrelevant in most regions after 2016 (2G network shutdown)

Can you post the link to the datasheet for your specific modem module, or post a sketch of the wiring that you are using to hook it all up.

If the parts are correctly rated - 12V to 5V@3A regulator should be fine - assuming both are not operating outside their specs.

The SIMCOM max current draw is typically only for a very short period during initial network negotiation - not during normal operation - so it sounds like some other issue.

Is the modem resetting, or the Arduino restarting - and sending a reset to the modem?