hello, i m trying to power my sim800 from a 12v dc supply, as sim800 work in 3.4-4.4v. i m using LM2576 ADJ to step down 12v to 4.2v. i have calculated value of resistor using a online calculator https://www.changpuak.ch/electronics/FeedbackCalculator.php , R1=8.2k & R2=3.3k. when i am using it on hardware its giving 5.16v instead of 4.2v. i have not connected any capacitor or diode as i just want to check voltage. Please suggest any simulation or provide proteus library for lm2576 as i am unable to find it.
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