SMTPassive Components: Resistors, Capacitors, Inductors

Passive Components

• Resistors

• Capacitors

• Inductors

Passive components (Two Terminals Packages):

A passive component is an electronic component that does not require a source of energy to perform its intended function. Examples of passive components include resistors, capacitors, inductors, and diodes.

Resistors:

The resistor is an electrical device. The primary function is to introduce resistance to the flow of electric current. The magnitude of opposition to the flow of current is called the resistance of the resistor. A larger resistance value indicates a greater opposition to current flow. The resistance is measured in ohms. An ohm is the resistance that arises when a current of one ampere is passed through a resistor subjected to one volt across its terminals. The various uses of resistors are setting biases, controlling gain, fixing time constants, matching and loading circuits, voltage division, and heat generation.

Capacitors:

An electrical device capable of storing electrical energy and releasing it at some predetermined rate at some predetermined time. It consists essentially of two conducting surfaces (electrodes) separated by an insulating material or dielectric. A capacitor stores electrical energy, blocks the flow of direct current, and permits the flow of alternating current to a degree dependent essentially upon capacitance and frequency. The amount of energy stored, E = 0.5 CV2.

SMT chip capacitors are shown above. As can be seen, these are very small in size (just like chip resistors). Chip capacitors are available in different sizes, and values.

Inductors:

Inductors are also available in chip form. However, you can not realize large values of chip inductors as it is practically unviable. A typical chip inductor is shown below:

• Notebook computers
• TV/VTR tuners
• Pagers
• Microcassettes
• Video cameras
• Telecommunication equipments
• Desktop computers
• Power line filters
• Cellular phones