This page allows you to calculate the size/value of feedback resistor required to run an LM1117 voltage regulator IC at the correct voltage, for your specific electronic circuit.
Click on any of the links at the top of the page to reveal (or hide) more information about this calculator.
Caveats:
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Definitions:
V
Output Voltage of the circuit.
R1
Value of Resistor between Vout and Vadj pins, typically specified as 220Ω
R2
Value of Resistor between Vadj and circuit ground.
Formulae:
V = 1.25 * (1 + R2 / R1)
Instructions
Enter an appropriate voltage/resistance value into each text-box in the form below.
Choose required unit-sizes for each value from each drop-down list.
Hit the ENTER or RETURN key on your keyboard, or press the 'CalcResult' button below the input fields.
A results area will appear at the bottom of the page, showing the required resistance value.
Press the 'Clear Results' button if you wish to discard the current results list, otherwise further calculations will be added to the bottom of the current results list.
