Beware of ADM861x!! This """"watchdog"""" is worse than nothing!

 Hi,

Would you mind sharing your schematic?

Thanks

Hi,

We have found the exact same problem. Can someone let us know how the above problem was solved? 

Regards

Anyone from Analog? We are finding the same problem. We have devices running in the field, that just stops working. On investigation we found that the ADM861x nRESET line was floating at 0.7V. This was with proper supply. You can remove the supply and put it back on, the nRESET line just stays at 0.7V. I eventually just connected 3.3V onto the RESET to get our main MCU to run again. Thereafter, the nRESET line was 3.3V again and I count not get the ADM861x to hang up again. I'm not sure what condition causes this behavior. We are using battery power devices, but we do make sure that they run normally. After the first power up we dont power cycle so we should not get the voltage monitor lockup as described in the datasheet? Or is that a wrong assumption? Is there something else that would cause this?

Hi,

We tested multiple units at 3.6V and observed no reset latching across all tested units, both with enabled and disabled watchdog. However, we have validated that the failure can be observed during testing when the unit is powered with a fast Vcc ramp.

Since your application uses a battery, we recommend applying an RC filter, if possible, to reduce the slew rate as recommended on page 12 of the ADM8611/ADM8612/ADM8613/ADM8614/ADM8615 datasheet (Rev. G) for battery-operated devices.

Regards,
Ivan

Hi,

In addition to the tests conducted, we continued to bench the unit using RC filter values and concluded that a rise time of 5ms or longer ensures that the reset latching failure does not occur.

Regards,
Harold