Is my SIM800L module burned?

Question

I have troubles with powering my SIM800L module. When it was powered from Arduino board using LM2596 DC/DC step-down converter (which is used to lessen voltage to 4.1V), the module restarted every 10 seconds. I have decided to power it up from 9V battery using same converter.

After setting it all up, I have plugged in the wires and the module worked for around 15 seconds and then powered down (signal LED was not blinking). I have measured the voltage and it was around 7.2 VDC. I don't know how that can happen because I have not changed converter settings. I then set up converter to 4.1 VDC again, but module has not started. Also I tried to power it up with 3.3V and 4.5V but nothing changed. Is there any solution for given problem? Have I burned my module?

Answer 1

You have most probably burnt the SIM800L module. When you were powering the buck converter- LM2596, from the Arduino, you didn't account for voltage drop hence the 4.1 volts was not the regulated voltage but rather the maximum the converter could give from a 5V input. Looking at figure 8 from the LM2596 datasheet gives a roughly .9v voltage drop at 25C and 1A load

When you connected the converter to 9V voltage it produced the actual voltage it was set for and this was excessive for the SIM800 hence it blew out.

Answer 2

Since you have tried to power it up with 3.3V and 4.5V but nothing changed, I think the SIM800L module is gone. If you want to bring another new SIM800L, it will be better to omit the buck module and use a 4V,2A power adapter like this: https://www.amazon.com/Mpkke-Supply-Replacement-Adapter-Center/dp/B07SBW8F1S In case if you wanna stick to the LM2596, you have to keep in mind that the LM2596 module can overheat if it's not adequately cooled, causing it to shut down intermittently. You can design a board like this and add a heatsink to it. https://www.pcbway.com/project/shareproject/_Buck_Converter_LM2596_bfb8ec50.html