Voltage regulator diodes (also known as Zener diodes) are mainly used in circuits for voltage stabilization, voltage limiting, circuit protection, etc. Through reasonable parallel application, the safety and stability of the circuit can be effectively improved.

Basic Principle

The Zener diode has the characteristic of stable reverse breakdown voltage. In the reverse working state, when the external voltage reaches its breakdown voltage (Vz), the diode conducts and keeps the voltage at both ends basically constant, so it can be used for voltage stability and protection.

Parallel Application Skills

1.Parallel connection for voltage clamping protection

  • Scenario: Protect digital circuit input ports and power lines from surge voltage or static electricity
  • Skills: The voltage regulator diode is reversely connected in parallel at both ends of the circuit to be protected
  • Selection notes:
    Its breakdown voltage is slightly higher than the normal working voltage, such as a 5.1V Zener diode for a 5V system;When the input is higher than the breakdown voltage, the diode is turned on and the excess current is shunted to the ground to protect the subsequent devices.

2.Use current limiting resistors for protection

When using a voltage regulator diode, a current limiting resistor should be connected in series, especially when the supply voltage is high and the load changes greatly, so as to avoid the instantaneous high current burning the Zener diode and also help to quickly stabilize the voltage.

Summary

The core concept of parallel connection of Zener diodes is to force current sharing and parameter matching. For high-reliability circuits, it is recommended to use a single high-power device or an integrated voltage stabilization solution. If parallel connection is necessary, be sure to connect a current sharing resistor in series and strictly screen the device parameters.

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