Principles and methods for selecting voltage zener diodes

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Principles and methods for selecting voltage zener diodes [Copy link]

1. Zener diodes are generally used as reference power supplies in voltage-stabilized power supplies. When working in the reverse breakdown state, pay attention to the connection method of positive and negative polarity. The positive pole of the tube is connected to the negative pole of the power supply, and the negative pole of the tube is connected to the positive pole of the power supply. When selecting a voltage-stabilizing tube, it is necessary to consider it according to the specific electronic circuit. For a simple parallel voltage-stabilizing power supply, the output voltage is the stable voltage of the voltage-stabilizing diode. The voltage-stabilizing power supply of a transistor radio can use a 2CW54 type of voltage-stabilizing tube, and its stable voltage can reach 6.5V.

2. The voltage-stabilizing value of the voltage-stabilizing tube is very discrete. Even if the same manufacturer and the same model of products, their stable voltage values are not exactly the same, this should be noted when selecting. For circuits with higher requirements, the voltage-stabilizing value should be tested before selection. 3. When using a voltage regulator, it should be noted that the reverse current of the diode cannot be increased infinitely, otherwise it will cause overheating and damage to the diode. Therefore, the voltage regulator generally needs to be connected in series with a current limiting resistor in the circuit. When selecting a voltage regulator, if a tube with a larger voltage regulation value is required and there is no tube at the maintenance site, several tubes with a lower voltage regulation value can be used in series; when a tube with a lower voltage regulation value is required and cannot be purchased, an ordinary silicon diode can be used in a forward connection instead of a voltage regulator. For example, two 2CA82A silicon diodes connected in series can be used as a 1.4V voltage regulator. However, voltage regulators are generally not allowed to be used in series. 34)]4. For the 2DW7 type three-electrode Zener diode, this type of Zener diode is a symmetrical package of two Zener diodes, so that the temperature coefficients of the two Zener diodes cancel each other out, improving the stability of the tube. The appearance of this three-electrode Zener diode is very similar to a crystal triode. When selecting, pay attention to the connection method of the pins. Generally, the two ends are connected and the middle is left hanging.

5. For the overvoltage protection Zener diode, the selection of its stable voltage should be based on the size of the protection voltage. The stable voltage value cannot be selected too large or too small, otherwise it will not play the role of voltage protection.

6. In the voltage stabilization circuit of tape recorders and color TVs, 1N4370, 1N746~1N986 series Zener diodes can be selected. Silicon Zener diodes, such as 2CW100~2CW121 series Zener diodes, can be used in the voltage stabilization circuits of electrical equipment and other radio electronic equipment.

7. When selecting a Zener diode, in addition to paying attention to parameters such as stable voltage and maximum operating current, you should also pay attention to selecting a Zener diode with a smaller dynamic resistance, because the smaller the dynamic resistance, the better the voltage stabilization performance. For example, the dynamic resistance of the 2CW53 Zener diode is less than 500 ohms, and the dynamic resistance of the 2CW55 Zener diode is less than 10 ohms.

QWE4562009

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shakencity

The voltage stability value of the voltage regulator is very discrete. Even if the same manufacturer and the same model of products, their stable voltage values are not exactly the same, this should be noted when selecting. For circuits with higher requirements, the voltage stability value should be tested before selection.