- A constant current diode (CCD) is also called a current limiting diode(CLD) and current regulating diode (CRD). It is an electronic device that regulates or limits current to a maximum value.
- It protects the circuit from harmful effects in the event of a short circuit.
- It consists of an n-channel junction field effect transistor(JFET) with the gate shorted to the source, which functions like a two-terminal current limiter or current source.
- It allows a current through it to rise to a certain value, and then level off at a specific value.
- Zener diodes keep the current constant instead of the voltage constant. These devices keep the current flowing through them unchanged when the voltage changes.
- Note that some devices are unidirectional and the voltage across the device must have only one polarity for it to operate as a CLD, whereas other devices are bidirectional and can operate properly in either polarity.
- It is used as a constant current source for LED drivers and can be used to replace holding coils in telephone connection devices.
- Examples of devices using constant current diodes include waveform generator circuits, timing circuits, and battery chargers.
