Semiconductor Tubes: Selection Guidelines for Semiconductor Gas Discharge Tubes

29 Sep,2020

Semiconductor Tubes: Selection Guidelines for Semiconductor Gas Discharge Tubes

  Semiconductor tubes It is an overvoltage protection device manufactured based on the thyristor principle. It relies on PN The breakdown current of the junction triggers device conduction and discharge, which may result in large surge currents or pulse currents. The range of its breakdown voltage defines the operating range for overvoltage protection.

When selecting a semiconductor discharge tube, Wuxi Precision recommends paying attention to the following points:

1. Maximum instantaneous peak current IPP It must be greater than the specified value stipulated by the communication equipment standard.

2. Steering voltage VBO It must be lower than the maximum transient peak voltage permitted by the protected circuit.

  3. When the semiconductor discharge tube is in the conducting state (on), the power loss is… P Should be less than its rated power. Pcm ， Pcm = KVT * IPP , among which K It is determined by the short-circuit current waveform. For exponential waves, square waves, sine waves, and triangular waves, K The values are respectively 1.00、1.4、2.2 and 2.8。

Semiconductor tubes

  4. Reverse breakdown voltage VBR It must be greater than the maximum operating voltage of the protected circuit. For example, in… POTS In the application, the maximum ringing voltage ( 150V ) of the peak voltage ( 150 * 1.41 = 212.2V ) and peak DC Bias voltage ( 56.6V ) the sum is 268.8V , therefore VBR Larger equipment should be selected above 268.8V the voltage. To give another example, in ISDN In the application, the maximum DC voltage ( 150V ) and the maximum signal voltage ( 3V ) the sum is 153V , therefore one should choose VBR Greater than 153V The equipment.

  5. To enable the semiconductor discharge tube to self‑reset after passing a large surge current, the device’s holding current… IH It must be greater than the current value that the system can supply. That is: IH (System voltage / Source impedance).

That concludes the information compiled by the editor of Wuxi Precision Steel Pipe Co., Ltd. Please contact us if you have any inquiries.


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