# What can we do with junction temperature of a transisto?

1. ## What can we do with junction temperature of a transisto?

What can we do with junction temperature of transistor

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2. ## Re: Junction temperature

What do you mean ? Do you want its effects on the device performance ? or the applications of junction temperature ?

Junction temperature is becoming more crucial now a days and can impact the device performance sometimes.

A high junction temperature will contribute to heat dissipation of the device and considering the theories, it might charge up the electrons to behave differently.

It also accounts for the energy level of carriers. If you study various transistor equations , you'll realise the exact impact of junction temperature on various parameters.

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3. ## Re: Junction temperature

Sorry for unclear question. Actually I want to use transistor as a thermal sensor instead of using expensive Thermistor. I want to know more details on the effects of junction temperature on transistor parameters such as hfe and so on...

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4. ## Re: Junction temperature

Silicon diodes (or BJT's Base-Emitter junction) are often used as temperature sensors ..

Here is some theory:
http://en.wikipedia.org/wiki/Silicon...erature_sensor
and here practical solution:
http://schematics.blogspot.com/2006/...ermometer.html

Regards,
IanP

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5. ## Re: Junction temperature

Junction temperature is an important internal variable to consider when designing with Power MOSFETs for example. These devices are usually used in switching power applications where the power dissipation of the device in conjuction with the thermal resistance of the device will increase the internal junction temperature of the device above its case temperature. Most devices have maximum junction temperature listed on their datasheet as $3T_{j,max}$. Exceeding these temperatures will severely reduce the reliability of the device and will lead to the device failing at some point.

Thermal resistance in electronics - Wikipedia, the free encyclopedia

Best regards,
v_c

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6. ## Re: Junction temperature

Here an example:

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