Capacitor Basics

What is a Capacitor?

Capacitors are components that can temporarily store electrical charge, and whose performance is determined by how much charge can be stored. As their name suggests, tantalum capacitors use tantalum to provide superior charge storage characteristics.

Capacitor Types

The 3 main types of capacitors on the market are aluminum electrolytic, multilayer ceramic, and tantalum capacitors. The characteristics and performance of each will differ due to the type of material used.

Aluminum Electrolytic Capacitor Multilayer Ceramic Capacitor Tantalum Capacitor
Aluminum Electrolytic Capacitor Multilayer Ceramic Capacitor Tantalum Capacitor
Type Aluminum Electrolytic Capacitor Multilayer Ceramic Capacitor Tantalum Capacitor
Dielectric Aluminum Oxide Various ceramics Tantalum Pentoxide
Voltage Range 4～400V 6.3～250V 2.5～50V
Capacitance 47～10000μF 0.001～100μF 0.47～1000μF
Advantages
  • Broad range of capacitances
    and breakdown voltages
  • Inexpensive
  • Good high-frequency characteristics
  • Non-polarized
  • Compact, large capacitance
  • Stable capacitance
Disadvantages
  • Leakage may limit lifetime
  • Large size
  • Polarized
  • Large capacitance variations
  • Prone to cracking and chipping
  • Failure mode: Short-circuit
  • Polarized

What is a Tantalum Capacitor?

Tantalum is a metal, whose name is derived from Tantalus, an anti hero from Greek mythology.
Generally, surface mount tantalum capacitors are constructed by forming electrodes at both ends of the tantalum element using a lead frame, then sealing the structure with mold resin.

Tantalum Capacitor

Capacitor Applications

Capacitors (including tantalum) are often used in the following applications.

Backup (Battery)

Backup Application

Utilizing as a battery

When the load current increases due to power supply interruption or a sudden rise in IC drive speed, the line voltage from the power supply may drop, possibly causing IC malfunction. To prevent this, charge stored in a capacitor is supplied to the IC, temporarily maintaining the line voltage.

Decoupling

Coupling Application

Utilizing AC characteristics

To supply stable DC voltage, capacitors are used to remove high-frequency noise caused by high-speed circuit drive or externally induced noise superimposed on the power supply line. Adopted in general power supply circuits.

Coupling

Coupling Application

In this application, the capacitor removes the DC bias voltage from the previous stage and only passes through the AC signal voltage.

Typically adopted in audio circuits.