Thermal - Heat Sinks for LM7806CT circuit

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ChristianMenzel

Banned
I have a bent circuit using an LM7806 voltage regulator off of a 12V DC wall wart to get 6V DC. It is a TO-220 package, currently using this little Thermal - Heat Sinks On my circuit.

Is this Heat Sinks good enough for my LM7806CT circuit? Output voltage 6V, input 35V, temperature 40°C ~ 125°C. It's TO-220-3 package.

crutschow

Well-Known Member
Depends upon the maximum output load current.
The LM7806 power dissipated will be the input voltage minus the output times the load current or (12V-6V) * ILoad.

MikeMl

Well-Known Member
With only convection, it says that the thermal resistance of that heatsink is 28.5 degC/W. Assuming you are willing to let the TO-220 get to 100degC with an ambient of 30degC, that is a (100-30) = 70degC rise. So that heatsink will disspitate 70degC*1W/28.degC = 2.46W.

The voltage drop across the 7806 will be (35V-6V)= 29V, so the maximum current will be P/E = 2.46W/29V = 85mA

ronsimpson

Well-Known Member
Assuming you are willing to let the TO-220 get to 100degC
Boiling water on you voltage regulator is not a good idea.
50C is much better. But then you are under 1 watt.

audioguru

Well-Known Member
What is the input voltage? First you said a 12V wall wart then later you said 35V.

oemcar

Member
more heat sink the better in a linear current heat dissipation app-
consider the surrounding area and put biggest heat sink you can within those physical limitations

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