PTC thermistor (Positive Temperature Dependent Thermistor) is a special resistance device. Its resistance value increases with the increase of temperature. The application principle of PTC thermistor in overcurrent protection is based on its characteristics of temperature sensitivity and positive temperature coefficient.
Overcurrent protection is a circuit protection mechanism used to protect the circuit from damage caused by excessive current. When the TPS74401RGWR When the current exceeds the rated value, the overcurrent protection mechanism will trigger, disconnect the circuit or reduce the current to protect the safe operation of the circuit and related equipment.
PTC thermistor can be used as overcurrent protection element, and its application principle is as follows:
1. Normal operation under rated current: under normal operating conditions, the temperature of PTC thermistor is low, its resistance value is small, and current can flow through it. At this time, PTC thermistors play the role of ordinary resistors without special protection.
2. Temperature rise under overcurrent condition: when the current in the circuit exceeds the rated value, the power loss in the circuit will cause the temperature rise of PTC thermistor. Due to the positive temperature coefficient characteristics of PTC thermistors, the resistance value will increase as the temperature rises.
3. The increase of resistance value leads to current limitation: as the temperature of PTC thermistor rises, its resistance value increases rapidly. This will cause the current through the PTC thermistor to decrease. When the current decreases to the normal operating range, the temperature of the PTC thermistor will also decrease accordingly.
4. Recovery after temperature drop: When the temperature of PTC thermistor drops to the normal operating range, its resistance value will return to the initial smaller value. In this way, the current can pass through the PTC thermistor and the circuit will return to normal.
To sum up, the application principle of PTC thermistor in overcurrent protection is through its positive temperature coefficient characteristics. When the current exceeds the rated value, the temperature rise of PTC thermistor will cause the resistance value to increase, thus limiting the current flow and realizing overcurrent protection. When the current returns to the normal range, the temperature of the PTC thermistor drops, the resistance value returns to a smaller value, and the circuit returns to normal.
The application of PTC thermistor in overcurrent protection has the following advantages:
1. Fast response: PTC thermistors respond very quickly to over-current events, can limit current in a very short time, and effectively protect circuits and equipment.
2. Self recovery characteristic: PTC thermistor will automatically recover to normal state after the over-current condition is relieved. When the current returns to the normal range, the temperature of the PTC thermistor drops, the resistance value returns to a smaller value, and the circuit returns to normal operation. This self recovery characteristic makes PTC thermistor very convenient and reliable in overcurrent protection.
3. Good thermal stability: the application of PTC thermistor in overcurrent protection is based on its temperature sensitivity. Because PTC thermistor has good thermal stability, it can work stably in a wide temperature range.
In a word, the application principle of PTC thermistor in overcurrent protection is to use its positive temperature coefficient characteristics to increase the resistance value through temperature rise, thus limiting the current flow and realizing overcurrent protection. Its fast response, self recovery characteristics and good thermal stability make it a common overcurrent protection element.
