Current limiting diodes (CLD) regulate current over a wide voltage range.
CLDs are used in many applications. Some examples include waveform generator circuits, battery charger, and timing circuits. CLDs are also used as a constant current source for driving LEDs and can also be used to replace holding coils in telephone connection devices. CLDs follow the life cycle stages defined by Electronic Industries Alliance (EIA) in EIA-724.
Types of Current Limiting Diodes
There are several types of CLDs. Examples include a current regulator diode, constant current diode, and current limit diodes.
- Current regulating diodes regulate the current flowing through them to a maximum level and if current exceeds its current regulation point, it drops its voltage.
- A constant current diode is similar to a junction field effect transistor (JFET) whose gate terminal is shorted to source. A constant current diode can automatically limit a current through a laser driver current limit diode over a wide range of power supply voltages.
- A laser driver current limit diode is the CLD that works on the principle of a quantum process whereby light is emitted due to transition of electrons from high-level to low-level energy states. Current limit diodes are employed for coupling and biasing the circuits. Other CLDs are also commonly available.
There are several ways in which CLDs function. A CLD is available in wide range of current and voltage ratings to control a current. Some examples of current limiting diodes specifications include a current rating of 35A to 15mA, peak voltage ratings of 50V to 100V, and impedance ranges from 20M ohm to several kilo ohms.
A current regulator diode can maintain a constant current for a voltage range of 1V to 100V if the current is in the range of 5mA to 60mA. Current regulating diodes also increase the frequency response, voltage gain, rejection ratio, and reduce gain losses and noise density.
A constant current diode has currents from 0.192mA to 5.6mA and operates in a voltage range of 1V to 50V. A constant current diode provides good temperature stability and does not require any biasing.
Some specifications of a laser driver current limit diode include current ranges of 0 to ± 20mA, ± 100mA, ± 200mA, ±5 00mA, ± 1A, ± 2 A, and 3dB analog modulation bandwidth. A laser driver current limit diode also supports both constant current and constant power modes of operation.
CLDs are designed and manufactured to meet most industry specifications.
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