External Watchdogs

dbutler · ‎2005-03-10

Posted on March 11, 2005 at 01:07

External Watchdogs

dbutler · ‎2005-02-23

Posted on February 23, 2005 at 11:07

Hello,

I am using an ST72F324 in a design. I know it has an on-board watchdog timer that can be used to generate an interrupt and an on-board LVD for low voltage supervision.

My question is, are these enough protection? Are they good enough for designs that require a modest amout of reliability?

For a design requiring a relatively high degree of reliability, would you use an external watchdog/brown out detector IC. I have looked at different devices ranging in price from $.10 to $1.00.

Can anyone share their experience in this area?

Thanks,

Dave

alok2 · ‎2005-03-10

Posted on March 11, 2005 at 01:07

The protection feature in the device are very reliable and used alot.

However the designers can take their own decisions for using the external protections for more reliability. Sometimes the cost of these external devices will be more than the micro itself.

For using the LVD the rise/fall time of power supply is mentioned in datasheet. If operation of power supply is out of this range, using external protection is fair enough. Similarly if the operation of device is in very noisy environment and subjected to EMI stress at the limit of specifications, external watchdog can be planned.