We will study two important zener diode models, each with familiar names! Zener breakdown is achieved by heavily doped regions in the neighbourhood of ohmic contact. To draw the characteristic curve of a Zener diode and to determine its reverse breakdown voltage. However, there is no appreciable change in voltage. Breaking News. However, above an extent the temperature may have some affect on the device as indicated in the graph below: It shows the zener diode temperature coefficient curve. The crucial difference between the Zener and Avalanche breakdown is the operating mechanism. The Piece-Wise Linear (PWL) Zener Model The Zener CVD Model Let’s see, we know that a Zener Diode in reverse bias can be described as: iI v V Zs Z ZK≈≈ <0 and Whereas a Zener in breakdown is approximately stated as: ivV On the other hand, Avalanche Breakdown occurs in the device due to the collision of electrons moving at high speed. Zener Diode & Zener Voltage Regulator Calculator Formulas and Equations for Zener Diode & Zener Voltage Regulator Calculator Series Current IS= VIN – VZ / .. Any current running through the p/n junction barrier generates the electrical power of: P = IZ * VZ This electrical power is equivalent to th e thermal power applied to this junction. The VI characteristic graph of the Zener diode is shown in the figure below. Typically there is also a minimum current required for the operation of the diode. the diodes anode connects to the negative supply. De pending on the duration and the intensity of breakdown voltage, the current increases widely even for a small change in voltage. So, when we plot the graph, we should get a curve very near to x-axis and almost parallel to it for quite sometime. Zener breakdown occurs when the high electric field is created across the junction. 1. Current : The current, IZM, of a Zener diode is the maximum current that can flow through a Zener diode at its rated voltage, VZ. It is the second method of disturbing the covalent bonds of the crystal atoms and increasing the reverse bias zener diode current, to be sustained at a much lower specific voltage than normal diode. This curve shows that the Zener diode, when connected in forwarding bias, behaves like an ordinary diode. From the I-V characteristics curve above, we can see that the zener diode has a region in its reverse bias characteristics of almost a constant negative voltage regardless of the value of the current flowing through the diode. Take the observations near the breakdown voltage by varying applied potential difference in the steps of 0.1 V. 6.Record all the observations in the table given. Up tp 93% Off - Launching Official Electrical Technology Store - Shop Now! 5.The reverse potential corresponding to this value of reverse. As a rough rule of thumb, this can be around 5 to 10 mA for a typical leaded 400 mW device. The Zener voltage (VZ) of a Zener or avalanche diode depends on the diode’s junction temperature. Zener/Breakdown Voltage – The Zener or the reverse breakdown voltage ranges from 2.4 V to 200 V, sometimes it can go up to 1 kV while the maximum for the surface-mounted device is 47 V. Current Iz (max) – It is the maximum current at the rated Zener Voltage (Vz – 200μA to 200 A) The Constant Voltage Drop (CVD) Zener Model 2. But when the reverse voltage applies across it and the reverse voltage rises beyond the predetermined rating, the Zener breakdown occurs in the diode. 25% Off on Electrical Engineering Shirts. 7.Plot the graph between V and I as shown. The Zener Diode is used in its “reverse bias” or reverse breakdown mode, i.e. In Zener breakdown, the increase in reverse voltage causes the expansion of the depletion layer. current is the breakdown or Zener-voltage of the Zener diode. 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