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BF609 thermal diode vs. Vcc - Latchup possible?

Question asked by schwarz on Mar 14, 2017
Latest reply on Apr 6, 2017 by Jithul_Janardhanan

Hi there,

I am looking for a on-chip temperature-sensing of the BF609.

And there is the built in thermal diode. (Pins: SYS_TDA, SYS_TDK).

Now I come to two questions:

  • Lets say the temperature sensor IC (in my case the max6698) senses a "high temperature" on the BF-die and consequently I shut down the BF-powersupply.

       Is it possible that there is some kind of a latchup?

       This because the temperature-sensing-IC will force its current (some hundreds of mikroamps) into the two pins of

       the BF - and the temperature sensor IC is NOT affected from the Vcc-Shutdown.

  • In my sensing-IC datasheet they are using a Base-Emitter-Diode of a Collector-Base-shorted NPN.

       The BF-datasheet talks about a grounded-collector Emitter-Base-Diode of a PNP.

       Will they be the same? That's the reason for the ideality-factor (which is in case of the BF609: n=1.006 ?!)


Thank you very much! Greetings from Hamburg,