Zener diode power dissipation

Zener diode power dissipation

Many of us are confused looking at the power dissipation specification of a Zener Diode from it's datasheet. Try to use whatever the formula you have, you might not arrive at the power mentioned in the datasheet. Browsing for the same also leads to different confusing results.

Go through this article to get to know the calculation be done for Zener power dissipation


Many of us are confused looking at the power dissipation specification of a Zener Diode from it's datasheet. Try to use whatever the formula you have, you might not arrive at the power mentioned in the datasheet. Browsing for the same also leads to different confusing results.

For a Zener diode,  if you look at it's datasheet, it mentions about the test current. The test current is measured at various stages in the Zener region. Generally, the common rating followed across the Zener is the test current mentioned at 1/4th of the power level. So, while calculating the power it has be multiplied by 4 times to arrive at the actual power consumption of the Zener diode.

​Zener power Dissipation = 4*IZT*VZT
​IZT = Test current at 1/4th the zener power
VZT = Zener voltage

​Take a look at the below snapshot from the 1N4728A - 1N4761A  Zener diode series of DIODES incorporated.


As per the above specification from the datasheet, the parameters required for calculating the power are,

IZT = Test current at 1/4th the zener power = 76mA
VZT = Zener voltage = 3.3V
​​Zener power Dissipation = 4*IZT*VZT = 4*76m*3.3 ~ 1000 (or 1W) 

The power dissipation specification in the same datasheet is as calculated above.


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