watchdog circuit 555 - open drain reset connection

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saurav_sdpl

Joined: 29 Sep 2006
Posts: 173
Helped: 2

30 Mar 2009 10:55 watchdog circuit 555

In my circuit i am using 555 timer as watchdog circuit and its output is connected to RESET pin of PL3150 which demands for an open drain reset.

For POR i am using DS1233 IC.
Is 555 timer suitable to drive a reset pin which asks for open drain reset connection, also is the output impedence of o/p pin of 555 low or high

xulfee

Joined: 27 May 2008
Posts: 434
Helped: 32
Location: Pakistan

31 Mar 2009 6:05 how to use 555 timer as watchdog

plz can u provide circuit diagram,i'm not getting wht u r asking

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dipnirvana

Joined: 23 Jan 2009
Posts: 207
Helped: 21
Location: India

31 Mar 2009 10:35 555 watchdog circuit

I don't understand why you want to connect output of a Timer (555) to a processor(PL3150) , as this will keep on reset the circuit. Instad if you want to have watchdog function, you should connect timer out to any IO port of PL3150 and firmware/application code should control the reset.