How to Select the Right Capacitor
How to Select the Right Capacitor
Capacitor
( noun )
a device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator
Most electronic devices employ some type of capacitor for electronic circuits, power circuits and power supply units. Capacitors are used in many applications such as power conversion, frequency conversion, noise filtering, audio crossover and DC buffering. However, finding the best capacitor for a given application isn’t always clear-cut. Let’s take a closer look.
Importance of capacitors
- Charging & discharging electric charges (electrical plug drawing)
- Keeping the voltage at the same level (circle with plus and minus drawing)
- Removing noise (sound frequency drawing with a slash through it)
Things to consider when designing (list with icons):
- Temperature
- Stability
- Frequency
- Longevity
- Voltage
- Piezoelectric Noise
- De-rating
- Physical size
- Flex protection
Polarization
Fixed capacitors
Polarized
- Electrolytic
- Tantalum
- Super Capacitors
Non-Polarization
- Film
- Ceramic
Technology vs Capacitance vs Voltage
(graph comparing voltage and capacitance values for each capacitor type)
Capacitor Types
(Line drawings, description/feature list, comparisons for voltage stability, lifetime, and capacity/unit volume for each type)
Tantalum
- Features relatively large capacitance and smaller in size compared aluminum electrolytic capacitors
- Ideal for most commercial applications
- Why? Has reached the maximum advancements in current technology; it also has the best voltage stability
- Focused applications: Telecom (5G because of the size), Industrial
- Voltage stability: Best
- Lifetime: Good
- Capacity/unit volume: Best
Tantalum Polymer
- Features excellent stability characteristics, highly resistant to vibration and very low ESR
- Ideal for high capacitance per volume applications
- Why? Dielectric breakdown occurs during high-frequency applications
- Focused applications: Aerospace, Telecom, Automotive
- Voltage stability: Good
- Lifetime: Best
- Capacity/unit volume: Best
Aluminum Polymer
- Features lower ESR, higher ripple current, no dry-out behavior and greater durability
- Ideal for high capacitance per volume, low ESR and ESL applications
- Why? New technology, slowly expanding lifespan technology
- Focused applications: Automotive, Computing
- Voltage stability: Best
- Lifetime: Best
- Capacity/unit volume: Best
Aluminum Electrolytic
- Offers high capacitance at an affordable price
- Ideal for low ESR and ESL applications
- Why? Nature of a liquid electrolyte, can evaporate and leak
- Focused applications: Automotive, Computing
- Voltage stability: Good
- Lifetime: Good
- Capacity/unit volume: Good
Film
- Provides high reliability with excellent properties in frequency and temperature
- Ideal for power, snubbing applications
- Why? Increased capacitance in this technology is not proportionate to the size
- Focused applications: Aerospace, Industrial Lighting, Telecom, Automotive and Renewable Energy
- Voltage stability: Good
- Lifetime: Best
- Capacity/unit volume: Better
Multi-Layer Ceramic (MLCC)
- Small size and incredibly robust, go-to for high-density designs
- Ideal for high-reliability, high-precision applications
- Why? Dielectric breakdown occurs with voltage bias in this technology, ceramics are heat-resistant but can crack
- Focused applications: Automotive, Industrial Power Conversion, Telecom
- Voltage stability: Good
- Lifetime: Good
- Capacity/unit volume: Good