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LM317 Help

Dave Benemerito

Sep 26, 2015
24
Joined
Sep 26, 2015
Messages
24
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
Screenshot_20180530-220055.png
When building the circuit, the output voltage was 3.1V which lower than recommended and might damage the module in my opinion
20180530_215319.jpg
20180530_214205.jpg
I have never powered the module. I would like to ask help what to do before i could damage the board. Thanks! :)
 

Chemelec

Jul 12, 2016
291
Joined
Jul 12, 2016
Messages
291
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

Mar 5, 2017
1,188
Joined
Mar 5, 2017
Messages
1,188
If the power supply is low enough ripple, just throw a silicon diode in series with it to drop ~ 0.7V
 
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