OPAMP temperature protection circuit

[legendkiller]

Hi,I am laying out an OPAMP in cadence IC 615using AMI 16 tech and would like to implement a thermal protection circuit that will shut off the power to the transistor if the temperature rises above a preset value. Could anyone point me in the right direction?

 

[KlausST]

HI,

decrease VR when temperautre is too hot.

Hope this helps.

 

[legendkiller]

that is correct, but How do I detect the temperature? I assume you would have to use a PTAT. anyone would be able to explaain how to go about it?

 

[KlausST]

HI,

I'm not familiar with ic design, but you can use the thermal drift of pn-voltage. It is about -2mV per degree celsius.

Hope this helps
Klaus