[time-nuts] One sure way to kill your FE-5680A or FE-5650A

[Hal Murray]

> The ATTinys have brownout detectors in them that’s supposed to keep them
> from going bonkers during undervolt periods. 

Startup and/or brownout has long been a nasty problem area for digital 
designers.

In the old old days, there was typically a R/C delay on the reset pin to a 
CPU.  That screwed up when the power supply ramped up slowly enough.  Most 
old timers have that merit badge.

Modern CPU chips often have specs like power must be OK for 200 ms before 
releasing Reset.  Anything like that will have at least one corresponding 
power monitor chip with several supply voltage inputs and the appropriate 
delay.

The brownout side gets ugly when you look at the tolerances.  The tolerance 
on the power monitor subtracts from the power supply tolerances.

There is another worm in the can.  How long does it take for your oscillator 
to get going?



-- 
These are my opinions.  I hate spam.