What is a freewheeling diode (flyback diode) and why is it used?
1 Answer
A freewheeling diode, also known as a flyback diode, is a diode used in electrical and electronic circuits to protect components from voltage spikes that occur when an inductive load is switched off. It's primarily used in applications where inductive loads, such as relays, solenoids, motors, and transformers, are present.
When an inductive load is switched off, the energy stored in the magnetic field of the inductor tries to maintain the current flow, causing a rapid decrease in the current. This abrupt change in current can lead to a phenomenon known as "inductive kickback" or "flyback voltage." This flyback voltage can produce high-voltage spikes that may damage or interfere with other components in the circuit.
A freewheeling diode is connected in parallel with the inductive load, but in the opposite direction of current flow. When the inductive load is switched off, the diode provides a path for the current to continue flowing, allowing the energy stored in the inductor to dissipate gradually. This prevents the voltage spikes and protects the circuit components from damage.
Here's how a freewheeling diode works:
During normal operation, when the inductive load is switched on, the current flows through both the load and the diode, forward-biasing the diode. The diode behaves as a closed circuit, and its voltage drop is relatively small.
When the inductive load is switched off, the inductor tries to maintain the current flow, and the diode now becomes reverse-biased. This prevents the inductive kickback voltage from reaching damaging levels, as the diode acts like an open circuit for the reverse voltage.
By providing a controlled path for the inductive energy to dissipate, the freewheeling diode helps to ensure the safety and reliability of the circuit. Without a freewheeling diode, voltage spikes from inductive kickback can cause electronic components to fail, lead to electrical noise, and even cause interference with other devices connected to the same power source.
In summary, a freewheeling diode (flyback diode) is an essential component in circuits with inductive loads, helping to protect other components from voltage spikes that occur when the inductive load is switched off.
When an inductive load is switched off, the energy stored in the magnetic field of the inductor tries to maintain the current flow, causing a rapid decrease in the current. This abrupt change in current can lead to a phenomenon known as "inductive kickback" or "flyback voltage." This flyback voltage can produce high-voltage spikes that may damage or interfere with other components in the circuit.
A freewheeling diode is connected in parallel with the inductive load, but in the opposite direction of current flow. When the inductive load is switched off, the diode provides a path for the current to continue flowing, allowing the energy stored in the inductor to dissipate gradually. This prevents the voltage spikes and protects the circuit components from damage.
Here's how a freewheeling diode works:
During normal operation, when the inductive load is switched on, the current flows through both the load and the diode, forward-biasing the diode. The diode behaves as a closed circuit, and its voltage drop is relatively small.
When the inductive load is switched off, the inductor tries to maintain the current flow, and the diode now becomes reverse-biased. This prevents the inductive kickback voltage from reaching damaging levels, as the diode acts like an open circuit for the reverse voltage.
By providing a controlled path for the inductive energy to dissipate, the freewheeling diode helps to ensure the safety and reliability of the circuit. Without a freewheeling diode, voltage spikes from inductive kickback can cause electronic components to fail, lead to electrical noise, and even cause interference with other devices connected to the same power source.
In summary, a freewheeling diode (flyback diode) is an essential component in circuits with inductive loads, helping to protect other components from voltage spikes that occur when the inductive load is switched off.