Body diode in MOSFET

Have you ever heard about it!

Mosfet is a metal oxide semiconductor field effect transistor. Main application of mosfet : it acts as a switch. A body diode is formed between substrate and source and drain region during manufacturing process. Some mosfet won’t have body diode.

Mosfet
Image by power electronics

So, purpose of this body diode is :

1. Reverse current flow: During switching application, when mosfet is in “ON”, diode is non- conductive, When mosfet is in “OFF” state, body diode allows current to flow in reverse direction thus prevents the mosfet.
2. Protection against Voltage spikes/ FLYBACK diode function: While in inductive loads, It acts as flyback diode to prevent the high voltage spikes due to sudden change in current.
3. External Diode Requirements: In some cases, precise control over body diode is necessary. An External diode might be used in parallel to bypass the body diode unwanted effects.

Thanks,

Sathya Priya N