CDLL5226A

CDLL5226A application field and working principle

The CDLL5226A is a general-purpose Zener diode with wide reverse-breakdown-voltage range and excellent Zener voltage regulation. The device is highly stable and extremely low in noise. It is particularly suited for portable applications due to its low leakage and low power consumption. The most common application for the CDLL5226A is to act as an electrical protection device, such as an overvoltage protection device, an inrush current limiter, or a transient overshoot limiter.

The diode’s reverse breakdown voltage is determined by the width of the semiconductor junction in its construction. Therefore, as the semiconductor junction changes in width during manufacturing, the reverse breakdown voltage of each CDLL5226A will vary slightly. This is why the reverse breakdown voltage can be specified as a range, rather than a single value.

When the CDLL5226A is connected in the reverse direction over a circuit with an applied voltage, the applied voltage must exceed the Zener breakdown voltage of the diode before it will operate. When the applied voltage becomes greater than the reverse breakdown voltage, the diode junction becomes forward biased and current starts to flow through it. The current flow through the diode begins to regulate the voltage, such that it stabilizes at the Zener breakdown voltage.

At this point, any further increase in the applied voltage is unable to increase the voltage across the diode and instead, will cause an increase in the current through the diode. This maximum allowable current is known as the Zener current, and the diode will not be able to stabilise the voltage across it. This makes the CDLL5226A an excellent voltage regulator.

In addition to its use as a voltage regulator, the CDLL5226A can be used as an inrush current limiter. When an AC voltage is applied to a CDLL5226A, the reverse breakdown voltage can be raised to accommodate a given peak AC voltage. This causes the diode to act like an inductor, and hence, limits the peak current through the diode.

Finally, the CDLL5226A can also be used as a transient overshoot limiter. When a sudden increase in the applied voltage occurs, the extra current flows through the diode, helping to limit the voltage overshoot. This helps to protect the circuit from any damage that may be caused by excessive overvoltage.