Purpose#

A clamping diode prevents voltage spikes generated by inductive components (such as solenoids and relays) from damaging sensitive control circuits. When inductive loads are de-energized, they generate reverse voltage transients that can exceed normal operating voltage by several hundred volts.

Specifications#

A standard 3-ampere clamping diode is sufficient for most automotive applications.

Recommended Components#

The following diode models have been successfully used in automotive control circuits:

• 1N4001
• 1N4002
• 1N4004

Note

These diodes are general-purpose rectifiers suitable for low-voltage automotive protection circuits. Verify amperage and voltage ratings match your specific application requirements.

Application#

Clamping diodes are typically connected in parallel across inductive loads with the cathode connected to the positive power supply and the anode to the load. This reverse-biased configuration allows the diode to conduct only when back-EMF voltage exceeds the forward bias threshold, effectively "clamping" the spike to a safe voltage level.