Overcurrent protection circuit manufacturer: points for attention when choosing resistor

Manufacturer of overcurrent protection circuit: tell you the precautions for selecting resistors

overcurrent protection circuitManufacturer: precautions for selecting resistors

There are many types of fixed resistors. The material and structure you choose will depend on the specific requirements of your application circuit. High-frequency circuits need to use unwinding resistors with low distributed inductance and small capacitance, such as carbon film resistors, metal resistors Metal oxide resistance, metal film resistance, carbon film resistance, winding resistance and other high-gain small-signal amplification circuits should use low-noise resistance instead of high-noise synthetic carbon film resistance and organic solid resistance

The winding resistance power is high, the current noise is low, the high temperature resistance is high, but the volume is large. The ordinary wirewound resistor is often used in the current limiting resistance, the voltage dividing resistance, the voltage dividing resistance or the bias resistance of the low-frequency circuit or the high-power tube. The high-precision wirewound resistor is mainly used in the fixed attenuator, the resistance box, the computer and various precision electronic instruments. The resistance value of the selected resistor should be close to the nominal value of the calculated value in the application circuit. Select the standard string The tolerance of the resistance used in general circuits is 5%. The resistance used in precision instruments and special circuits must be precision resistance. The rated power of the selected resistor must meet the requirements of the power capacity of the resistor in the application circuit. In general, theovercurrent protection circuitmanufacturer believes that the power of the resistor should not be increased or decreased at will. If the circuit requires power resistance, The rated power can be one to two times higher than the power required by the actual application circuit. Generally speaking, it can be selected from several specific situations

1. Rated power: under the specified ambient temperature and humidity, assuming no ambient air circulation, the power that the resistor can dissipate under the condition of long-term continuous load damage or basically unchanged performance, in order to ensure safe use, the rated power is usually 1-2 times higher than the power consumed by the circuit

2. Tolerance: the large allowable deviation range between the actual resistance value and the nominal resistance value of the resistor and the product accuracy it represents

3. Working voltage: the voltage that the resistor will not be damaged due to overheating or electric breakdown during long-term operation. When the voltage exceeds the specified value, the resistor will generate sparks, noise or damage

4. Stability: stability is an index to measure the degree of resistance change under external conditions

5. Noise electromotive force: The noise electromotive force of the resistor can be ignored in normal circuits, but cannot be ignored in weak signal systems. Traditionally, the noise of the wirewound resistor is only determined as thermal noise, which is only related to the frequency band, temperature and applied voltage of the resistor. In addition to thermal noise, the film resistor also has current noise, which is roughly proportional to the applied voltage

Overcurrent protection circuitThe manufacturer's editor has explained it to you today. If you need resistors or varistors, you can contact our over-current protection circuit company