ATMEGA128 external watchdog needed?

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Hi,

I am using an ATMEGA128 with the internal watchdog. Why would someone recommend me use an external watchdog chip? I ran my design across some engineers for a second set of eyes and they all mentioned I need an external watchdog. Is the internal watchdog not sufficient? Any ideas on this? Could there be issues with the internal one?

Thanks.

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If you are making life critical equipment then you want all the precautions you can get otherwise the internal watchdog should be fine.

Are the "engineers for a second set of eyes " familiar with AVR sfuff?

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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The watchdog has its own independent RC clock. Thats about all you can ask from a plain watchdog. If the other eyes are also thinking of low voltage detection, that is available, also, as the BOD (Brown Out Detector).

Of course, for life-safety equipment, you want everything you can get. But barring that case, the combo of the built-in watchdog + BOD will do everything an external one will do.

Jim

 

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