The zener diode can be used as a voltage regulator to provide a constant voltage from a power source where the voltage may vary within a specific range. As the voltage stabilizing diode has the function of voltage stabilizing, it is applied in many circuits, such as voltage stabilizing power supply, amplitude limiting circuit, overvoltage protection circuit, compensation circuit, etc.

Stabilizer diode parameters include: stable voltage; Iz: rated current; Rz: dynamic resistance; Pz: rated power consumption; α： Temperature coefficient; IR: Reverse leakage current.

1. Uz: stable voltage

It refers to the stable voltage value generated at both ends when the voltage stabilizing tube passes through the rated current. This value varies slightly with the operating current and temperature. Due to the difference in manufacturing process, the voltage stabilizing value of the same type of voltage stabilizing tube is not completely consistent. For example, Vzmin and Vzmax of 2CW51 type voltage stabilizing tube are 3.0V and 3.6V respectively.

2. Iz: rated current

It refers to the current value passing through the voltage stabilizing tube when it generates a stable voltage. When it is lower than this value, the voltage stabilizing tube can also stabilize the voltage, but the effect will become worse; Above this value, as long as the rated power loss is not exceeded, it is also allowed, and the voltage stabilization performance will be better, but it will consume more electric energy.

3. Rz: dynamic resistance

It refers to the ratio of voltage change and current change at both ends of voltage stabilizer. The ratio varies with the working current. Generally, the larger the working current is, the smaller the dynamic resistance is. For example, when the working current of 2CW7C voltage stabilizing tube is 5mA, Rz is 18 Ω; When the working current is 10mA, Rz is 8 Ω; When it is 20mA, Rz is 2 Ω;> 20mA basically maintains this value.

4. Pz: Rated power consumption

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

5. α： temperature coefficient

If the temperature of the voltage stabilizing tube changes, its stable voltage will also change slightly. The relative change of the voltage at both ends of the tube caused by the temperature change of 1 ℃ is the temperature coefficient (unit:%/℃). Generally speaking, a voltage stabilization value lower than 6V is Zener breakdown, and the temperature coefficient is negative; Those higher than 6V belong to avalanche breakdown, and the temperature coefficient is positive. When the temperature rises, the depletion layer decreases. In the depletion layer, the valence electrons of the atom rise to a higher energy, and the lower electric field strength can excite the valence electrons from the atom to generate Zener breakdown, so its temperature coefficient is negative. The avalanche breakdown occurs when the depletion layer is wide and the electric field intensity is low. The increase of temperature increases the vibration amplitude of lattice atoms, which hinders the movement of carriers. In this case, avalanche breakdown can only occur when the reverse voltage is increased, so the voltage temperature coefficient of avalanche breakdown is positive. This is why the voltage stabilizing value of the voltage stabilizing tube with a voltage stabilizing value of 15V gradually increases with the temperature, while the voltage stabilizing value of the voltage stabilizing tube with a voltage stabilizing value of 5V gradually decreases with the temperature. For example, the temperature coefficient of 2CW58 pressure stabilizing tube is+0.07%/° C, that is, the pressure stabilizing value will increase by 0.07% every time the temperature increases by 1 ° C.

In case of high requirements for power supply, two regulators with opposite temperature coefficients can be used in series as compensation. Due to mutual compensation, the temperature coefficient is greatly reduced, which can reach 0.0005%/℃.

6. IR: Reverse leakage current

It refers to the leakage current generated by the zener diode under the specified reverse voltage. For example, when VR of 2CW58 voltage stabilizing tube=1V, IR=O.1uA; When VR=6V, IR=10uA

Model of zener diode:

1、2CWX. In the X or 2CWXX type voltage stabilizing tube (the symbol "X" indicates the Arabic code in the voltage stabilizing value), the numerical value after 2CW indicates the voltage stabilizing value, in volts (V). For example, 2CW0.7 indicates that the voltage stabilizing value is 0.7V; 2CW2.7, indicating that the voltage stabilizing value is 2.7V; 2CWl5, indicating that the voltage stabilizing value is 15V, etc.

2. In MAXXXX voltage stabilizing tube, the last three digits of four Arabic numerals indicate that the voltage stabilizing value is XX.XV. For example, the voltage stabilizing value of MAl043 is 4.3 V; The voltage stabilizing value of MAl360 is 36V; The voltage stabilizing value of MA2130 is 13V; The MA4150 has a voltage stabilization value of 15V, etc.

3. In BZX55C voltage stabilizing tube, the letters and numbers after 55C represent the voltage stabilizing value. For example, the voltage stabilizing value of BZX55C6V8 is 6.8V; The voltage stabilizing value of BZX55C27 is 27V; The voltage stabilizing value of BZX55C110 is 110V, etc. The pressure stabilizing value marking rules of BZX79A, BZX79C and BZX85C tubes are the same as those of BZX55C series.

4. The voltage stabilizing value of 3Al, 3A2, 3A3, 3Cl, 3C2, 3C3 and other types of voltage stabilizing tubes is 3V, and the Arabic numerals behind the letter A or C represent the voltage stabilizing value error.