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LDO thermal shutdown circuite

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fjord

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bjt thermal shutdown

Can anyone help me to design thermal shutdown for LDO? Where I can find some schematic or books about thermal shutdown?

Thanks
 

about thermal shuntdown

one way to design thermal shutdown is to utilize BJT's dependancy on temperature. You can find the VBE of the BJT at the shutdown temperature you want and compare it with a reference voltage you generated from your bandgap.
 
thermal shutdown

I know but, I need some schematic. Thanks for answer
 

thermal shutdown circuit

Just use comparator.

One input of comparator should be reference voltage, the other input has two~three bjt (serial)with current source.
i.e., 2Vbe or 3Vbe should be another input.

You can trim reference voltage with 2~3Vbe by simulation for trimming thermal shutdown voltage.

Sorry to say 'I have no schematic'.
Hope it can help you.

Regards.
 

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    fjord

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thermal shutdown design

Yes, I was trying something like this but in my technology I have only lateral pnp bjt. I can't use 2 or 3 bjt in serial :( Thanks for help :)
 

ldo thermal shutdown circuit

fjord said:
Yes, I was trying something like this but in my technology I have only lateral pnp bjt. I can't use 2 or 3 bjt in serial :( Thanks for help :)
Click to expand...
1 is sufficient, I dont see why you would want to use more than 1.
 

bjt with thermal shutdown

If you really want to use 2 VBE, maybe you can try this:
 

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    fjord

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