The SMZ11 series PTC thermistor is a protective element that automatically protects and recovers abnormal temperatures and currents, commonly known as a "self recovery fuse" or a "ten thousand fuse". Our company's SMZ11 series PTC thermistors are used for general line overcurrent and overload protection, such as transformers, micro motors, switching power supplies, chargers, adapters, instruments, electronic coils, control panels, household appliances, air conditioners, microwave ovens, etc.
 
Features of SMZ11 series PTC thermistor products: 
1. The SMZ11 series products are resin coated lead type 
2. Suitable for continuous operation under high resistance voltage of 15-265VAC 
3. Complete specifications 
4. Long term stability 
5. After product overload protection, there is no need to set it again 
6. The switch has no contacts and no noise
Application scope of SMZ11 series PTC thermistor products:
1. Switching power supply
2. Voltage regulator, adapter, charger, energy meter, multimeter
3. Electronic coils and control panels
4. Household appliances (air conditioning, microwave oven lights)
5. Electronic circuits
6. Instrumentation

Application principle of SMZ11 series PTC thermistor products:
The principle is shown in Figure 2: when the circuit is in normal state, the current passing through the PTC is less than the rated current, and the PTC is in normal state with a small resistance value, which will not affect the normal operation of the protected circuit. When a major fault occurs in the circuit and the current greatly exceeds the rated current, PTC generates heat in vain and presents a high configuration, causing the circuit to be in a relatively "disconnected" state, thereby protecting the circuit from damage. After troubleshooting, the PTC also automatically returns to the low resistance state, and the circuit returns to normal operation.
When selecting PTC thermistors as overload protection components, first confirm the maximum normal operating current of the circuit (i.e. the non operating current of the PTC thermistor) and the highest ambient temperature at the installation location (during normal operation) of the PTC resistor. Next are the protection current (i.e. the operating current of the PTC thermistor), maximum operating voltage, rated zero power resistance, and also consider factors such as the external dimensions of the components.
As shown in Figure 4, use ambient temperature. The relationship between non operating current and operating current. The operating current is usually 2-3 times the non operating current, and as the working temperature increases, both the non operating current and the operating current will decrease accordingly.


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