Voltage Divider Calculator
Calculate output voltage, current, and power for various voltage divider circuits
Voltage Divider Configuration
Component Values
Analysis Results
Formula used: V₂ = V₁ × R₂/(R₁ + R₂)
Input: 12V, Components: 1000Ω, 2000Ω
Circuit Analysis
Example: Resistive Voltage Divider
5V to 3.3V Level Shifter
Input Voltage: 5V (microcontroller logic level)
Desired Output: 3.3V (sensor input level)
R₁: 1kΩ (chosen for low current)
Load Current: Assume high impedance load (>100kΩ)
Calculation
R₂ = (Vout × R₁) / (Vin - Vout)
R₂ = (3.3V × 1kΩ) / (5V - 3.3V)
R₂ = 3300 / 1.7 = 1941Ω
Standard value: R₂ = 2kΩ
Actual output: 3.33V (0.9% error)
Divider Types
Resistive
DC and AC circuits
Most common, simple calculation
RC Filter
Low-pass filter
Attenuates high frequencies
CR Filter
High-pass filter
Blocks DC, passes AC
Capacitive
AC circuits only
High voltage applications
Common Applications
Level Shifting
Convert 5V to 3.3V logic levels
Sensor Interfacing
Scale sensor outputs to ADC range
Reference Voltage
Create stable voltage references
Potentiometer
Variable voltage control
Design Tips
Use high impedance dividers to minimize loading
Add buffer amplifier for low impedance loads
Consider temperature coefficients of components
Use precision resistors for accurate ratios
Account for component tolerances in design
Understanding Voltage Dividers
What is a Voltage Divider?
A voltage divider is a passive linear circuit that produces an output voltage that is a fraction of the input voltage. It consists of two impedances connected in series across a voltage source. The output voltage is taken from the junction between the two impedances.
Key Principles
- •Current is constant through series-connected components
- •Voltage divides proportionally to impedance ratios
- •Output voltage is always less than input (passive circuit)
- •Loading effects can significantly alter output voltage
Basic Formulas
General Formula:
V₂ = V₁ × Z₂/(Z₁ + Z₂)
Resistive Divider:
V₂ = V₁ × R₂/(R₁ + R₂)
Capacitive Divider:
V₂ = V₁ × C₁/(C₁ + C₂)
AC vs DC Behavior
While resistive dividers work with both AC and DC signals, reactive components (capacitors and inductors) only function properly with AC signals. The impedance of reactive components depends on frequency, making them useful for filtering applications.
Frequency Dependence: Capacitive reactance Xc = 1/(2πfC) and inductive reactance XL = 2πfL both vary with frequency, enabling filter design.
Design Considerations
Output voltage drops when connected to low impedance loads
Higher currents increase power loss and heat generation
Resistor tolerances affect output voltage accuracy