Temperature Dependency of zener diode

Jhead's picture

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Joined: Oct 10, 2019

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Temperature Dependency of zener diode
October 10, 2019 - 8:15pm

I wanted to study the effect of temperature change on diode characteristics. I used a 1N4739A 9.1 V Zener diode for that and connected it in reverse bias. Since the meter is not that sensitive to measure leakage current, I increased the voltage above 9 volt to breakdown region. Introducing a heat source to the vicinity of the diode, the current starts decreasing.

How do we explain that behaviour? The diode resistance is supposed to decrease with increase in temperature right?

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Power vs Temperature in a Zener Diode
October 11, 2019 - 12:17pm

Hi Jhead, 

The detials that you are looking for is already available in the datasheet of 1N4728

https://www.vishay.com/docs/85816/1n4728a.pdf

As you increase the temperature the power dessipation of the Diode decrease which means current through the diode is decreasing do to the rise in resistance. So your experimental set-up will also show rise in resistance (decrease in current thus power) as you increase the temperature of your diode. The graph I am talking about is shown beow 

Capture_2.PNG

Also there is no fixed considtion that the resistance of an electronic component will deacrease for increase in temperature. It depends on the type of components, to understand better you should read about NTC (Negative temperature co-effecient) and PTC (Positive temperature co-effecient) 

Hope this cleared your doubt