Tools/Decoupling Capacitor Calculator

Decoupling Capacitor Calculator

Calculate optimal bypass capacitor values for your ICs

Input Parameters

Supply Voltage (V)

Max Ripple Voltage (mV)

Transient Current (mA)

Switching Frequency (MHz)

Results

Recommended Capacitor

2.2µF

Minimum: 2.00 µF

Actual Ripple

45.45 mV

Ripple %

1.38%

Use low-ESR ceramic capacitors (X5R, X7R)

Best Practices

Place capacitors as close to IC pins as possible
Use multiple capacitor values for broadband filtering
Keep traces short and wide
Connect directly to ground plane via

Typical Combinations

Digital ICs

100nF + 10µF per power pin

High-Speed Circuits

10nF + 100nF + 10µF

Analog ICs

100nF + 10µF ceramic

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Understanding Decoupling Capacitors

Why Decoupling Matters

Decoupling capacitors provide local energy storage to supply transient current demands from ICs. Without proper decoupling, voltage rails can droop during switching events, causing logic errors or analog noise. They also filter high-frequency noise from the power supply.

Capacitor Selection

Choose ceramic capacitors (X5R, X7R) for high-frequency decoupling due to their low ESR. Combine with larger bulk capacitors (electrolytic or tantalum) for low-frequency filtering. The resonant frequency of the capacitor should match the noise frequency you want to filter.