Voltage Division

Calculating

Quick Reference

Voltage Division Calculations

Solved for Vout

Vout = Vs * (R2 / R1 + R2)

Solved for Bottom-half of Divider (R2)

R2 = (R1 * Vout) / (Vs - Vout)

Current at Vout

I = V / R1

Where R1 is the top-half of the divider.

Netduino Characteristics

Analog-to-Digital Convert (ADC) Impedance

The Netduino ADC has an impedance value of approximately 11kΩ.

5V to 3.3 Voltage Divider Resistor Values

When level-shifting to a 5V voltage domain to a 3.3V voltage domain for use with the Netduino ADC, the following resistor values are recommended:

R1 = 1kΩ
R2 = 2.2kΩ

More Info

Voltage division is a complex topic, and covered much more in-depth in part 5 of the electronics tutorial.