Introduction to the method and main parameters for determining the type of zener diode

Zener diodes can be used as voltage regulators to provide a stable voltage for power supplies that may vary from voltage within a specific range. Due to the voltage stabilizing function of voltage stabilizing diodes, they have been applied in various circuits such as voltage stabilizing power supplies, amplitude limiting circuits, overvoltage protection circuits, compensation circuits, and so on. The following is the relevant knowledge of zener diode models and basic parameters. I hope it can bring you reference and help.

The parameters of the voltage stabilizing diode are: voltage stabilizing; Iz: Rated voltage; Rz: Dynamic resistance; Pz: Rated power consumption; α： Temperature coefficient; IR: Reverse leakage current.

1. Uz: steady voltage

Refers to the voltage stabilizing value generated on both sides of the voltage stabilizing tube based on the rated voltage. This value varies slightly depending on the operating current and temperature. Due to different processing techniques, the voltage stabilizing values of the same type of voltage stabilizing tube are not completely consistent. For example, the Vzmin and Vzmax of a 2CW51 regulator are 3.0V and 3.6.6V, respectively.

2. Iz: Rated voltage

Refers to the current value through the pipeline when the voltage stabilizing tube generates a stable voltage. When less than this value, although the stabilizing tube can also stabilize the pressure, the stabilizing effect will become worse; When above this value, as long as the rated power consumption is not exceeded, it is also allowed, and the voltage stabilizing characteristics will be better, but more power consumption is required.

3. Rz: Dynamic resistance

Refers to the ratio of voltage change to current change on both sides of the regulator. The ratio varies depending on the operating current. In general, the greater the operating current, the smaller the dynamic resistance. For example, when the working current of the 2CW7C regulator is 5ma, Rz is 18 Ω; When the working current is 10mA, Rz is 8 Ω; Rz is 20mA Ω at 20mA;> 20ma basically maintains this value.

4. Pz: Rated power consumption

Determined by the allowable temperature of the chip, its value is multiplied by the stable voltage Vz and the allowable maximum current Izm. For example, the 2CW51 voltage stabilizing tube Vz is 3V, Izm is 20ma, and the tube Pz is 60mw.

five α： temperature coefficient

If the temperature of the regulator tube changes, its stable voltage will also change slightly. The relative change in voltage on both sides of the pipeline caused by a temperature change of 1 ℃ is the temperature coefficient (enterprise:%/℃). Generally speaking, a stabilized voltage value less than 6V belongs to Zener penetration, and the temperature coefficient is negative; The avalanche breakdown is higher than 6V and the temperature coefficient is positive. As the temperature increases, the depletion layer decreases. In the depletion layer, the valence electrons of the atom rise to higher kinetic energy, and a smaller field strength can stimulate the valence electrons to generate Zener penetration from the atom, resulting in a negative temperature coefficient. When the depletion layer is wider and the field strength is lower, the temperature of avalanche breakdown increases, increasing the vibration range of lattice atoms, and limiting the movement of carriers. In this case, avalanche breakdown can only occur by increasing the reverse voltage, so the voltage temperature coefficient of avalanche breakdown is positive. This is why the voltage stabilizing value of a 15V voltage stabilizing tube gradually increases with temperature, while the voltage stabilizing value of a 5V voltage stabilizing tube gradually decreases with temperature. For example, the temperature coefficient of the 2CW58 pressure stabilizing tube is 0.07%/° C, which means that each time the temperature rises by 1 ° C, its pressure stabilizing value will increase by 0.07%.

For places with high power requirements, two voltage stabilizing tubes with opposite temperature coefficients can be used as compensation. Due to mutual compensation, the temperature coefficient can be greatly reduced, reaching 0.005%/℃.

6. IR: Reverse leakage current

Refers to the leakage current generated by a voltage regulator diode at a specified reverse voltage. For example, when 2CW58 regulator VR=1V, IR=0.1uA; When VR=6V, IR=10uA.

Model of zener diode:

1. "Type 2CWX. X or 2CWXX (marked with" X "indicates the Arabic code in the voltage stabilizing value) In the voltage stabilizing tube, the data value after 2CW represents the voltage stabilizing value, in volts (V). For example, 2CW0.7 represents the voltage stabilizing value of 0.7V; 2CW2.7 represents the voltage stabilizing value of 2.7V; 2CWL5 represents the voltage stabilizing value of 15V, and so on.".

2. In the MAXXXX type regulator, the last three digits of the four Arabic data indicate that the regulator value is XX.XV. For example, the stabilized voltage value of MAl043 is 4.3V; The regulated voltage of MAl360 is 36V; The regulated voltage of MA2130 is 13V; The stable voltage value of the MA4150 is 15V, etc.

3. The letters and numbers on the back of the BZX55C 55C regulator display the regulator value. For example, the regulated voltage of BZX55C6V8 is 6.8V; The stabilized voltage value of BZX55C27 is 27V; The voltage stabilization value of BZX55C110 is 110V, etc. The pressure stabilizing values of BZX79A, BZX79C, and BZX85C type tubes indicate the same laws and regulations as the BZX55C series.

4. The voltage stabilizing value of type 3AL, 3A2, 3A3, 3CL, 3C2, and 3C3 voltage stabilizing tubes is 3V, and the Arabic numerals following the letter A or C indicate the voltage stabilizing value deviation.

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