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

Bob Camp kb8tq at n1k.org
Thu Jun 9 07:42:34 EDT 2016


Based on the number of different ways there seem to be to corrupt the operating software
in the FE Rb’s …. they seem to have a unique problem. There are a *lot* of devices
using the same basic parts that don’t turn into a brick when this or that happens.


> On Jun 9, 2016, at 4:31 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
>> 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.
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