Voltage Divider Calculator
Calculate output voltage (Vout) and total current (Itotal).
Input Values
CALCULATED RESULTS
Output Voltage (Vout)
--- V
Total Current (Itotal)
--- mA
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Understanding Voltage Dividers
A voltage divider is a simple passive linear circuit that produces an output voltage (Vout) that is a fraction of its input voltage (Vin). It is formed by two resistors (R1 and R2) connected in series.
Formula
The output voltage is calculated using the formula:
Vout = Vin * (R2 / (R1 + R2))
The total current flowing through the series resistors is:
Itotal = Vin / (R1 + R2)
Applications
- Providing a reference voltage.
- Reducing a voltage to a level suitable for an ADC (Analog-to-Digital Converter).
- Level shifting logic signals (with considerations).
Important Considerations
- Loading Effect: The output voltage can be affected if the load connected to Vout draws significant current. The load resistance should be much larger than R2 (typically at least 10 times) to minimize this effect.
- Power Dissipation: Resistors must be rated to handle the power they will dissipate: P = I2R or P = V2/R.
- Tolerance: The actual output voltage will vary based on the tolerance of the resistors used.
Frequently Asked Questions
What is a voltage divider used for?
A voltage divider is primarily used to create a reference voltage or to scale down a voltage to a level required by another circuit, such as the input of an Analog-to-Digital Converter (ADC). It's a fundamental building block in analog electronics.
What is the "loading effect"?
The loading effect occurs when a load (another circuit component) connected to the output (Vout) draws a significant amount of current. This load effectively becomes a parallel resistor to R2, changing the overall resistance and thus altering the output voltage from the ideal calculation. To minimize this, the load's resistance should be at least 10 times greater than R2.
Can I use a voltage divider to power a device like a motor or a microcontroller?
It is generally not recommended. Voltage dividers are inefficient for power delivery as they constantly dissipate power through the resistors. They are also unregulated, meaning the output voltage will drop significantly under a variable load (like a motor). For powering devices, a dedicated voltage regulator (like a linear regulator or a buck converter) is a much more stable and efficient solution.