A Common Type Of Circuit Protection

Overcurrent protection
（Over current）
It is automatically powered off when the current is too large to prevent damage caused by the components in the circuit exceeding the [1] rated current.

Overvoltage protection
(Over-Voltage Protection)
Mainly to prevent overvoltage or electrostatic discharge (Discharge Suppression) damage to electronic components, is widely used in telephones, fax machines and high-speed transmission interfaces (USB, IEEE1394, HDMI, SATA) and other electronic system products, especially electronic communication equipment, for how to avoid voltage abnormalities (Over-voltage or EOS (Electrical Over-Stress) or electrostatic discharge (ESD) that causes damage to electronic equipment, which is particularly important.

Over-temperature protection
（OT）
Temperature protection components from the beginning of commercialization, has gone through a nail, over-temperature protection components are widely used in the temperature has special requirements for occasions, such protection components according to the principle of actuation can be divided into chemical actuation type, low temperature alloy actuation type, of which the main feature of chemical actuated products is that can do low-temperature products (there is 48 °C), but the structure is more complex, the cost is higher; Low temperature alloy type actuation is mainly a large diameter of low temperature fuse to play a conduction role, must ensure that the heat generated by the rated current will not melt the fuse, this low temperature fuse is generally by adjusting the proportion of tin (Sn), copper (Cu), silver (Ag), bismuth (Bi), indium (In) and other components to adjust its melting point.

Overtemperature and overcurrent protection
（TFR）
In recent years, with the improvement of applications, the simple temperature protection function can no longer meet the needs of the safety protection of electrical appliances, motors, motors and 3C products, so it has developed components that can monitor and protect in time at the same time in response to abnormal temperature, current and voltage, and the rise of such components is mainly lithium-ion batteries and lithium polymer batteries as the largest applications.

Overcurrent and overvoltage
（OCOV）
With the complexity of modern electronic products, the requirements for the use of protection components are also increasing, such as the comprehensiveness of protection, limited reserved space, etc., with the proposal of these requirements, the protection component industry has set off a boom in combination packaging, such as the above mentioned over-current over-temperature protection is also a kind of combined packaging, but over-current over-voltage protection combination packaging products are still in the research and development stage, and there are no mature commercial products on the market.