What is ESR in Capacitors and Why It Affects Circuit Performance

When selecting capacitors for electronic circuits, one critical factor that often gets overlooked is ESR – Equivalent Series Resistance. ESR directly impacts the efficiency, heat generation, and overall reliability of your circuit, especially in high-frequency and power applications. In this blog, we’ll break down what ESR is and why it’s important to consider when buying capacitors.

What is ESR in Capacitors?

Equivalent Series Resistance (ESR) is the internal resistance that appears in series with the ideal capacitance of a capacitor. It represents the resistive losses within the capacitor and is measured in ohms (Ω).

Why is Low ESR Important?

Improved Efficiency: Lower ESR means less power is wasted as heat, making circuits more energy-efficient.

Better High-Frequency Response: Low ESR capacitors maintain stability and filtering capability at high frequencies.

Reduced Heat Generation: Lower ESR reduces internal heating, extending the capacitor’s lifespan.

Essential for SMPS and Motherboards: Switching power supplies and high-performance motherboards require low ESR capacitors to handle rapid voltage changes.