I have bought SIM808 module, everything working fine. All AT commands are giving expected response, i'm accessing it through hyperterminal. My problem is that whenever i make or receive a call or SMS , GSM gets restarting.(I can able to make/receive call, getting ring/alert for small period of time and then interrupt). But there is no Under or Lower voltage power down or warning. I have tried with DC power supply of 5V/500mA , 5V/1A and 5V/2A. What might be the reason ? Please help. extra info : It has one LM2576S voltage regulator in-built.


Check the datasheet and I think you will find you need 3 amps peak. It requires this peak current when you make a call or send a text/sms.

Use a 5A power supply and that should solve the problem.

I have never tried it but "super capacitors" might work, providing the extra power when its needed, it depends how long you need the 3A for.

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    Thanks Matt for reply. I dnt have datasheet for that module. Bt according to SIM808 datasheet, it's peak current is 2A and voltage is 3.4 to 4.4. so i dnt know for module, how much input should be given – sankar Feb 20 '17 at 12:48
  • does the module withstand with 5A current ? @Matt – sankar Feb 21 '17 at 6:55
  • I got the solution for my problem. With 12V-1.5A power supply, it works fine. – sankar Feb 27 '17 at 3:56

I too faced the same problem and solved it.

Just use a 3.3V logic converter or a 3.3V interface, as the 5V causes the device to restart.

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