What Is a Power Switch?
A power switch is a device that creates an electrical connection between power or ground and a load. These switches are categorized into two main types: IC-based switches, which utilize electronic circuits with components like MOSFETs on silicon substrates, and mechanical contact switches.
The term encompasses a wide range of switches, from simple mechanical load switches to smart power switches found in power management ICs, each tailored to specific applications.
Uses of Power Switches
Mechanical switches are widely used in applications requiring human interaction. They are essential in various devices and machines, such as industrial robots, home appliances, lighting equipment, automobiles, and personal computers. These switches come in various structures, including pushbutton, toggle, slide, seesaw, reed, rotary, and tactile types.
Toggle and rotary switches are often used for power on/off functions and circuit or power level switching. Tactile switches are commonly found in PC keyboards.
Principle of Power Switches
The basic principle of power switches involves physically switching electrical circuit connections. In mechanical switches, this is achieved by human operation, while in IC switches, it’s done through the ON/OFF operation of transistors like MOSFETs. The power circuit is controlled by the movement of electrode contacts in relation to fixed contacts.
Switches are technically defined by terms like ‘throw’ and ‘pole.’ ‘Throw’ refers to the number of control paths a switch can handle, while ‘pole’ indicates the number of circuits it can control simultaneously. For example, a ‘Double Poles Double Throws’ (DPDT) switch can control two circuits in two different ways.
With push-button switches, it’s important to distinguish between normally OPEN and CLOSE positions, indicating the switch’s state when pressed. Power switches also require careful consideration of maximum rating specifications, including current and voltage limits, to prevent overheating or damage due to arcing.
When selecting a power switch, considerations should include whether the bias is DC or AC and the specific load conditions, as these factors influence the switch’s current and voltage ratings.