The three characteristics of POSISTOR can be illustrated as in the following.

a). Resistance - Temperature Characteristic

b). Static Characteristic (Voltage-Current Characteristic)

c). Dynamic Characteristic (Current - Time Characteristic)

Resistance - Temperature Characteristic

The resistance almost remains constant between room temperature (25°C) and the Curie point.

When the temperature exceeds the Curie point, the resistance suddenly increases. Utilizing this characteristic, abnormal conditions where a circuit is overheated beyond a specified temperature are detected, and the circuit can be shut down.

What can be done by utilizing this characteristic?

When the temperature becomes more than the detection temperature, a PTC can reduce the current flow!

Example, LED bulbs; LED elements which is the core of LED bulbs, are electronic components that are extremely weak to heat. When a large current flows through an LED element while heat is applied to the LED element, the LED element will be damaged.

The PTC comes into play in such conditions! The PTC detects the temperature around the LED element, and when the temperature reaches a specified temperature (detection temperature), the resistance of the POSISTOR suddenly increases to reduce the current flow. Accordingly, the PTC prevents damage of LED elements by heat. Since the resistance of a POSISTOR increases suddenly, the digital conversion of the temperature information is not required.

The temperature can be detected with a simple circuit!

Nice can provide PTC from a low Curie point of 40°C to as high as 300°C.

Static Characteristic (Voltage-Current Characteristic)

 According to Ohm's Law, the current of the fixed resistance increases along with the application of a voltage.  On the other hand, the current in a PTC remains the same as the fixed resistance up the C point, according to Ohm's Law. However, when the current exceeds the C point due to self-heating, and the resistance of the PTC itself increases, the current of the PTC decreases along with the increase in the voltage. Thus, the PTC has a characteristic to maintain electric power at a constant.  What can be done by utilizing this characteristic?  Heater The PTC is utilized in constant temperature heating elements, heaters and etc., taking advantage of these characteristics. The PTC is different than a Nichrome heater, etc., and maintains a constant temperature without performing ON/OFF control. Overcurrent Protection When an anbnormality occurs in an electronic circuit, a large current (overcurrent) will flow. Utilizing this characteristic, the PTC limits the current in the circuit, so that an overcurrent does not flow into other electronic components, when this overcurrent flows.

PTC limits the current in a circuit, to protect from overcurrents.

Dynamic Characteristic (Current - Time Characteristic)

when a voltage is applied to a PTC, the characteristic is a large current flows because the resistance is low at the moment a voltage is applied, and the resistance increases by the self-heating of the PTC along with the elapsed time, and the current which flows into the PTC decreases.

Many things can be realized using a PTC! !  A PTC allows for the initial inflow of a large current, and subsequently the current can be decreased by the self-heating.  For example, a compressor used in refrigerators. The compressor is equipped with a motor, and a large current is required to start the motor. A PTC is used because the components which allow the initial inflow of a large current, and reduces the current after a certain time has passed, is required!