LM317 Help

[Dave Benemerito]

Hi,
I have a SIM800L module with no voltage regulator on it. I have power it between 3.7V to 4.4V. I was using LM317 to regulate the power from the supply (4.6 to 5V) using two resistors 220Ω and 470Ω

When building the circuit, the output voltage was 3.1V which lower than recommended and might damage the module in my opinion


I have never powered the module. I would like to ask help what to do before i could damage the board. Thanks!

 

[Chemelec]

You need to get an "LDR" Type of Regulator.
LDR = LOW DROP OUT.

The LM317 has too High of a Voltage Loss between Input and Output.

 

[dave9]

If the power supply is low enough ripple, just throw a silicon diode in series with it to drop ~ 0.7V