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How to Protect Your Power Mosfet From Burning Out

A power MOSFET is an electrical component optimized for switching. Like regular transistors, it is made from a semiconductor and has at least three leads. One of the MOSFET̵7;s leads, called the gate, has a glass-like layer. This layer prevents the gate from having electrical contact with the drain and source leads, but also makes the device very sensitive to static electricity. Electrostatic discharge is one source of MOSFET burnout. Another source is operating the device beyond its current and voltage specifications. To protect a power MOSFET from burning out, use preventative measures to avoid or dissipate static electricity and to protect it from transients.

Things You'll Need

MOSFET
Anti-static material, such as plastic or foam
Zener diode

Instructions

- 1
  Insert the MOSFET into a piece of anti-static foam when it is not being used in a circuit. The foam must be large enough to cover the three leads.
- 2
  Store loose MOSFETs in anti-static bags. The most common ones used for components are metalized plastic bags that are silver in color. This procedure should be done in addition to protecting the MOSFET leads with the anti-static foam.
- 3
  Ground yourself before working with MOSFETs. Do this by briefly touching metal before handling them.
- 4
  Place an anti-static mat on the floor of your work area. This also discharges static.
- 5
  Wear an anti-static strap on your wrist and place an anti-static plastic covering on your work table or desk. These help prevent static buildup. Also, avoid bringing materials prone to electrostatic discharge -- such as plastic cups -- near the circuit.
- 6
  Turn the power off before adding MOSFETs to circuits. Make sure the power is off before removing them also.
- 7
  Add a heatsink. Some MOSFETs have built-in ones in the form of metal tabs, but others do not have any extra protection from overheating.
- 8
  Add a zener diode between the drain and source leads. The zener acts to suppress surges, and also guards against noise or a power supply that is accidentally connected in reverse. The zener is also necessary if the load is inductive, such as a solenoid, motor or relay. Inductive loads use magnetic fields.
- 9
  Place one or two zener diodes at the gate. The purpose of the zeners is to make sure that the input voltages do not exceed the MOSFET's specification.

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