DDZ8V2ASF-7 Discrete Semiconductor Products

The DDZ8V2ASF-7 diodes are a part of the single Zener class of diodes. These are semiconductor devices that are typically used for the purpose of the protection of electronic circuits from the damaging effects of voltage transients which may occur in their external environment. This device functions on the Zener break-down principle, wherein a reverse biasing of the device to a particular voltage causes the formation of a ‘Zener tunnel’ and a high drain current flows through the device.

The primary application field of the DDZ8V2ASF-7 diode is in the generation of a regulated reference voltage for a variety of purposes, such as protection of circuitry against the output of power supplies, or the control of motor speeds and various other applications. In addition to its use in generating a regulated voltage, the device can be used as a voltage limiting device or to protect circuits from inductive loading. The DDZ8V2ASF-7 diode is available in a range of power ratings, ranging from 0.1 watt to 5 watt.

In order to understand its working principle, one needs to understand how a Zener diode breaks down. When the applied electrical field between two oppositely doped regions of a reverse biasing diode reaches a certain threshold (known as the Zener voltage), the Zener tunnel which forms in the junction between them generates new electrons which serve to activate more electrons. This electron multiplication is known as avalanche effect. Once the avalanche effect increases the current flow to a certain level, the voltage across the device clamps to the Zener voltage and causes the diode to break down. The relationship between Zener voltage and the power dissipation of the diode is given by the following expression:

Vz = K(Pd)^2/3

where Vz = the Zener voltage, Pd = power dissipation and k = a constant.

This Zener breakdown voltage is responsible for allowing a current to flow through the diode, even when it is reverse biased against the supply voltage. The current which is allowed to flow through the diode is limited to the Zener current and any voltage applied to the diode should exceed the Zener voltage or junction voltage to allow any current to flow through it. The wattage rating of the device determines the maximum amount of current which can be supported and the value of the Zener voltage.

The package of the DDZ8V2ASF-7 diode is a standard TO-92 plastic through-hole package. This package offers excellent protection against vibration, thermal effects and moisture. The package contains an internal epoxy seal which offers protection from vibration and mechanical shock, and also contains a drain port for draining static electricity. The internal portion of the package is made up of a dielectric body, which is coated to prevent corrosion.

The device also has a Zener diode testing circuit, which can be used to check the Zener voltage and its component values to ensure they meet their specifications. This test circuit also allows one to check the current and reverse current characteristics of the diode before it is put into use. The device is also well suited for use in the production of wide range voltage regulators and can be used in areas where long term reliability is important such as telecommunications, automotive, and metering applications.