Reverse voltage, particularly in the context of a diode, is a voltage applied across the device in a specific orientation. Unlike forward voltage, which allows current to flow easily, reverse voltage typically blocks current flow until a certain limit is reached.
Understanding Reverse Voltage in Diodes
When we talk about the reverse voltage of a component like a diode, we are describing the voltage difference across it when it is connected in a way that it is not designed to conduct significant current. For a standard diode, this happens when the positive terminal of the voltage source is connected to the diode's cathode and the negative terminal to the anode.
The Definition from Our Reference
According to our reference dated 18-Jul-2017, the reverse voltage is specifically defined based on this connection orientation:
"The reverse voltage is the voltage drop across the diode if the voltage at the cathode is more positive than the voltage at the anode (if you connect + to the cathode)."
This means that when the cathode side of the diode has a higher electrical potential than the anode side, the voltage measured across the diode is considered the reverse voltage.
Key Characteristics and Implications
Our reference highlights several important points about reverse voltage:
- Orientation: It occurs when the cathode is made more positive than the anode.
- Magnitude: This voltage is usually much higher than the forward voltage (the voltage required for significant current flow in the conducting direction).
- Current Flow: Normally, a diode allows very little current to flow when reverse biased. However, as the reference states, "a current will flow if the connected voltage exceeds this value." This crucial point refers to the reverse breakdown voltage.
Reverse Breakdown Voltage
The "value" mentioned in the reference where current starts to flow when reverse voltage is applied is known as the reverse breakdown voltage. Each diode has a maximum reverse voltage it can withstand. If the applied reverse voltage exceeds this breakdown voltage:
- The diode's insulating properties in the reverse direction break down.
- A large current begins to flow through the diode in the reverse direction.
- This phenomenon can be used intentionally in components like Zener diodes for voltage regulation.
- For standard rectifier diodes, exceeding the reverse breakdown voltage, especially if the current is not limited, can damage or destroy the diode due to excessive heat.
Understanding reverse voltage is critical for properly designing and protecting electronic circuits that use diodes.
