The Zener diode is a special diode that achieves voltage stabilization by utilizing its constant voltage characteristic in the reverse breakdown region. Its normal operating conditions and status include the following points:

Working conditions

  • Reverse bias
    The Zener diode must be in a reverse bias state, that is, its cathode (K) voltage is higher than the anode (A) voltage.
  • Working voltage is within the regulated range
    The reverse voltage of the Zener diode should reach its breakdown voltage (regulated value), but not exceed its maximum reverse working voltage.
    When designing a circuit, the current is usually controlled by a current limiting resistor to ensure that the reverse current of the Zener diode does not exceed its rated value.
  • Current is within the allowable range
    The operating current of the Zener diode must be within its rated regulated current range, that is, between I_Z(min) (minimum regulated current) and I_ZM(max) (maximum regulated current).
  • Proper power consumption management
    The power consumption of the Zener diode should meet its maximum power consumption capability (P = Vz × Iz), otherwise it may cause overheating and damage.

Working state

  • Breakdown voltage regulation state
    When the reverse voltage reaches the breakdown voltage (Vz) of the Zener diode, the diode enters the breakdown voltage regulation state. At this time, the reverse current increases rapidly, but the voltage remains basically constant (Vz).
  • Non-breakdown state
    When the reverse voltage is lower than the breakdown voltage (Vz), the reverse current of the Zener diode is very small (leakage current, almost negligible), and the voltage regulation effect will not be achieved.
  • Forward conduction state
    If a forward bias is applied, the Zener diode will show the characteristics of an ordinary diode, and the voltage drop is about 0.7V (silicon material) when forward conduction. In this state, it does not have the voltage regulation function.

Overvoltage protection applications

Zener diodes are suitable for protecting power lines, power control lines, and can protect internal circuits and ICs from overvoltages caused by hot plugging, etc.

Normal working conditions and status of Zener diode-Protection Devices-TVS Diodes-ESD Protection devices-Gas Discharge Tube-Thyristor-Pled Protectors-Mov

Power lines are susceptible to electrostatic discharge (ESD) and other overvoltage pulses and must be protected. The specific cause of a circuit disconnection is not always clear, but it's often due to overvoltage, such as when switching inductive loads. Zener diodes make protecting circuits and ICs easier and safer.

Application Areas

  • Simple regulated power supplies (such as 5.1V and 12V regulators)
  • Voltage divider regulator circuits
  • Microcontroller and power module input protection
  • Communication interface and sensor protection
  • Analog-to-digital converter (ADC)
  • Voltage comparator
  • Signal interface protection
  • Audio or video amplifier input limiting
  • Undervoltage and overvoltage indicator circuits
  • Battery low voltage alarm circuits
  • MCU, FPGA, and logic circuit input protection
  • Communication interface protection (UART, CAN, RS485, etc.)

More Information

For more product details of zener diode, please visit the website:

https://en.semiware.com/products/zener

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