How can diodes be used to protect electronic circuits from voltage spikes?
1 Answer
Diodes can be used to protect electronic circuits from voltage spikes by acting as voltage clamps or voltage limiters. When a voltage spike occurs, it can exceed the safe operating limits of the components in the circuit and cause damage. Diodes can redirect or limit the excessive voltage to protect the sensitive components. There are two common types of diode-based protection circuits: the Zener diode and the Schottky diode.
Zener Diode Voltage Clamp:
A Zener diode is a special type of diode designed to operate in reverse breakdown region. When the voltage across a Zener diode exceeds its breakdown voltage (also known as the Zener voltage), it allows current to flow in the reverse direction, effectively clamping the voltage to its breakdown value.
To protect against voltage spikes, the Zener diode is placed in parallel with the circuit, and its breakdown voltage is selected to be slightly higher than the maximum allowable voltage for the components. When a voltage spike occurs, the Zener diode will start conducting in reverse, diverting the excess current away from the circuit and preventing the voltage from rising beyond the Zener voltage.
Schottky Diode Voltage Limiter:
Schottky diodes have a low forward voltage drop compared to regular diodes, which makes them suitable for high-frequency applications. They can be used as voltage limiters to protect against voltage spikes.
In a voltage limiter circuit, the Schottky diode is connected in series with the circuit. When the voltage spike exceeds the forward voltage drop of the Schottky diode, it starts conducting, limiting the voltage across the circuit. This prevents the voltage from rising to dangerous levels.
It's important to note that while diodes can provide some level of protection against voltage spikes, they might not be sufficient for highly sensitive circuits or extremely high voltage spikes. In some cases, additional protection devices like transient voltage suppressors (TVS diodes) or metal oxide varistors (MOVs) may be used in conjunction with diodes to provide more robust protection against voltage transients. These protection devices are designed to handle larger energy dissipation during transient events, offering better protection for sensitive electronic components.
Zener Diode Voltage Clamp:
A Zener diode is a special type of diode designed to operate in reverse breakdown region. When the voltage across a Zener diode exceeds its breakdown voltage (also known as the Zener voltage), it allows current to flow in the reverse direction, effectively clamping the voltage to its breakdown value.
To protect against voltage spikes, the Zener diode is placed in parallel with the circuit, and its breakdown voltage is selected to be slightly higher than the maximum allowable voltage for the components. When a voltage spike occurs, the Zener diode will start conducting in reverse, diverting the excess current away from the circuit and preventing the voltage from rising beyond the Zener voltage.
Schottky Diode Voltage Limiter:
Schottky diodes have a low forward voltage drop compared to regular diodes, which makes them suitable for high-frequency applications. They can be used as voltage limiters to protect against voltage spikes.
In a voltage limiter circuit, the Schottky diode is connected in series with the circuit. When the voltage spike exceeds the forward voltage drop of the Schottky diode, it starts conducting, limiting the voltage across the circuit. This prevents the voltage from rising to dangerous levels.
It's important to note that while diodes can provide some level of protection against voltage spikes, they might not be sufficient for highly sensitive circuits or extremely high voltage spikes. In some cases, additional protection devices like transient voltage suppressors (TVS diodes) or metal oxide varistors (MOVs) may be used in conjunction with diodes to provide more robust protection against voltage transients. These protection devices are designed to handle larger energy dissipation during transient events, offering better protection for sensitive electronic components.