1N974A

The 1N974A is a low-cost, low-level Zener diode with a break down voltage of 4.7 volts, manufactured in a small SOD-80C surface mount package (2.6 x 2.6 x 1.6 mm). It has a very low current leakage – typically only 0.5 µA at room temperature – and the high temperature stability of the breakdown voltage makes them suitable for use either as a Zener diode or a shunt regulator.

This type of diode is commonly used in low-voltage power supplies, current-limiting circuits, voltage clamping applications, and voltage referencing. Its low current and low cost make it one of the most popular diodes in the electronics industry.

A Zener diode is a PN junction diode designed to be operated in the breakdown region. This occurs when the P-type and N-type semiconductor layers are connected to each other and the voltage is reversed. When the applied voltage reaches the Zener voltage (Vz) of the diode, a large reverse current flows from the N-type to the P-type region and a breakdown occurs.

The breakdown voltage of a Zener diode is determined by the amount of doping (5 phosphorus atoms per 1 silicon atom) used in the N-type layer and the width of the depletion region. The higher the doping level, the wider the depletion region and the lower the breakdown voltage. Therefore, a higher doping level will produce a lower breakdown voltage, and a low doping level will produce a higher breakdown voltage.

When the diode is reverse biased, the depletion region between the P and N regions widens and allows the electrons to flow from the N region to the P region. As the voltage across the diode continues to increase, the avalanche breakdown of the diode occurs and the current increases sharply.

The 1N974A is a low-cost, low-level Zener diode with a break down voltage of 4.7 volts, manufactured in a small SOD-80C surface-mount package. It is often used in low-voltage power supplies, current-limiting circuits, voltage clamping applications, and voltage referencing. It has a very low current leakage – typically only 0.5µA at room temperature – and the high temperature stability of the breakdown voltage makes them suitable for use either as a Zener diode or a shunt regulator.