How to Calculate Voltage Divider
What is Voltage Divider?
Calculates output voltage from a resistor network dividing input voltage. Used for ADC inputs, sensor interfaces, and voltage scaling.
Formula
Formula: Vout = Vin × (R2 ÷ (R1 + R2))
- R2
- R2 value — Variable used in the calculation
- R1
- R1 value — Variable used in the calculation
Step-by-Step Guide
- 1Two resistors in series across supply voltage
- 2Output taken between resistors
- 3Formula: Vout = Vin × (R2 ÷ (R1 + R2))
- 4Select resistors to achieve desired output voltage
Worked Examples
Input
V1=12V, R1=1k, R2=1k
Result
Vout=6V
Common Mistakes to Avoid
- ✕Not buffering voltage divider with low-impedance load
- ✕Using very small resistor values (excessive power)
Frequently Asked Questions
What affects voltage divider accuracy?
Load impedance (must be much higher than resistor values), temperature stability, resistor tolerance.
How do I buffer a voltage divider?
Use op-amp buffer to isolate divider from load; prevents voltage drop under load.
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