PTC thermistor selection guide for electronic ballasts

The following is a circuit diagram of [Selection Guide for PTC Thermistor for Electronic Ballasts]

PTC thermistor selection guide for electronic ballasts

Based on increasing the delay time, it can be achieved by increasing the Curie temperature and volume, reducing the resistance, etc., and determining the following basic principles:
1. When the energy-saving lamp works, the temperature inside the lamp is high, and the Curie temperature of the PTC thermistor should not be too low, otherwise the delay time is too short, and the preheating effect is not obtained, and the Curie temperature is above 100 °C;
2. When the starting line is a single capacitor, the PTC thermistor has a higher withstand voltage requirement, usually above 800V;
3. The PTC thermistor with high resistivity can be greatly improved in reliability, and should be preferred under the premise of satisfying the startup characteristics;
4. The situation at low temperature start-up must be considered. At low temperatures, the thermal balance resistance of the PTC thermistor is correspondingly low, which may cause the lamp to not start;
5. The switching life of the PTC thermistor is preferably greater than 100,000 times;
6. The warm-up time cannot be less than 0.4 seconds;
7. After the startup is completed, the power consumption of the PTC thermistor should comply with the relevant regulations.
external structure

Application principle: The PTC thermistor is used in the electronic ballast of the energy-saving lamp. The product can be directly connected to the resonant capacitor of the lamp tube without changing the line. The hard start of the electronic ballast and the electronic energy-saving lamp can be changed to preheat. Start-up, the preheating time of the filament reaches 0.4-2.0 seconds, which can extend the life of the lamp more than four times.

The PTC thermistor is used to realize the preheating start as shown in the following figure: When the switch is turned on, Rt is in the normal temperature state, its resistance value is far lower than the resistance value of C2, and the current passes through C1, Rt to form a loop preheating filament. After about 0.4-2 seconds, the Rt Joule heat temperature exceeds the Curie temperature Tc and jumps into a high resistance state, and its resistance value is much higher than the C2 impedance. The current forms a loop through C1 and C2 to cause L resonance, and a high voltage lighting lamp is generated.
For a particular electronic ballast or electronic energy-saving lamp, the larger the PTC resistance value, the smaller the volume, and the lower the Curie temperature, the smaller the power consumption and the shorter the warm-up time; The greater the power consumption, the longer the warm-up time.

Electronic energy-saving lamp preheating soft start circuit diagram

(Editor: Circuit Diagram)