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

[Bob Camp]

Hi



> On Jun 9, 2016, at 3:31 PM, Nick Sayer via time-nuts  
> wrote:
> 
> 
>> On Jun 9, 2016, at 10:11 AM, Bob Camp  wrote:
>> 
>> 
>> One very real possibility is: The reason we *have* all these parts is that 
>> they
>> have a bug in them, and were scrapped out  because of it.
>> 
> 
> From what I’ve read elsewhere (and I can’t find a citation right now), they 
> (at least the FE-5680As) were used in cell phone bases that were 
> decommissioned after network upgrades.

That’s always been the leading theory. It matches up with the reason you 
see a lot of other ex-cell gear out of China. It may or may not be correct
in this case. We never ever seem to get a fully authoritative answer to those
sort of questions.

Bob

> 
>> Bob
>> 
>> 
>>> On Jun 9, 2016, at 8:03 AM, Clint Jay  wrote:
>>> 
>>> It would seem so bit I don't remember seeing a 'reset'  chip in the 5680.
>>> I'm wondering if there's scope to add one onto the rail that runs the PSD
>>> and 80C320 to keep it in reset.
>>> On 9 Jun 2016 13:00, "Bob Camp"  wrote:
>>> 
 Hi
 
 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.
 
 Bob
 
> On Jun 9, 2016, at 4:31 AM, Hal Murray  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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Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A

[Nick Sayer via time-nuts]

> On Jun 9, 2016, at 10:11 AM, Bob Camp  wrote:
> 
> 
> One very real possibility is: The reason we *have* all these parts is that 
> they
> have a bug in them, and were scrapped out  because of it.
> 

>From what I’ve read elsewhere (and I can’t find a citation right now), they 
>(at least the FE-5680As) were used in cell phone bases that were 
>decommissioned after network upgrades.

> Bob
> 
> 
>> On Jun 9, 2016, at 8:03 AM, Clint Jay  wrote:
>> 
>> It would seem so bit I don't remember seeing a 'reset'  chip in the 5680.
>> I'm wondering if there's scope to add one onto the rail that runs the PSD
>> and 80C320 to keep it in reset.
>> On 9 Jun 2016 13:00, "Bob Camp"  wrote:
>> 
>>> Hi
>>> 
>>> 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.
>>> 
>>> Bob
>>> 
 On Jun 9, 2016, at 4:31 AM, Hal Murray  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.
 
 
 
 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
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Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A

[Bob Camp]

Hi

Their design is hardly unique in not having a dedicated supervisory part in it.
There are a *lot* of designs that work very well using basically the same 
parts they use, without using a reset chip. 

Without a lot of digging into exactly what is going on, there isn’t much of a 
way to be sure of a fix. 

One very real possibility is: The reason we *have* all these parts is that they
have a bug in them, and were scrapped out  because of it.

Bob


> On Jun 9, 2016, at 8:03 AM, Clint Jay  wrote:
> 
> It would seem so bit I don't remember seeing a 'reset'  chip in the 5680.
> I'm wondering if there's scope to add one onto the rail that runs the PSD
> and 80C320 to keep it in reset.
> On 9 Jun 2016 13:00, "Bob Camp"  wrote:
> 
>> Hi
>> 
>> 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.
>> 
>> Bob
>> 
>>> On Jun 9, 2016, at 4:31 AM, Hal Murray  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.
>>> 
>>> 
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
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Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A (Hal Murray)

[BIll Ezell]

When I interviewed at a large IC mfgr in Santa Clara many years ago, one 
of the questions was basically that - how do you reliably handle startup 
state in a CPU? Of course the correct answer is, you can't with 100% 
certainty. You can make the likelihood small, but there's always some 
obscure case you never thought of. Even hysteresis, clock-count delays, 
etc. have failure modes. Say you hold the reset for 200 msecs, then 
there's a transient. Now your reset circuitry has to be designed so that 
it can reset itself, and you can't guarantee that. And yes, I've used 
the RC hack before.


They also had another trick question, how do you handle a condition 
where you have contention for a resource and one contender has higher 
priority and you want to guarantee it always gets the resource? You of 
course can't. There will always be some, possibly very small, time 
window where you have already made the allocation decision. I think it 
had something to do with multi-port memory or some such.



On 6/9/2016 12:00 PM, time-nuts-requ...@febo.com wrote:

Re: One sure way to kill your FE-5680A or FE-5650A (Hal Murray)
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.



--
Bill Ezell
--
The day Microsoft makes something that doesn't suck
will be the day they make vacuum cleaners.
Or maybe Windows 10.

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

[Clint Jay]

It would seem so bit I don't remember seeing a 'reset'  chip in the 5680.
I'm wondering if there's scope to add one onto the rail that runs the PSD
and 80C320 to keep it in reset.
On 9 Jun 2016 13:00, "Bob Camp"  wrote:

> Hi
>
> 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.
>
> Bob
>
> > On Jun 9, 2016, at 4:31 AM, Hal Murray  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.
> >
> >
> >
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
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Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A

[Bob Camp]

Hi

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.

Bob

> On Jun 9, 2016, at 4:31 AM, Hal Murray  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.
> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [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.



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

[David]

NAND Flash is especially bad about this.  Not only can the data being
currently erased or programmed be corrupted but other data can be
also.  That is why NAND Flash drives are so prone to complete failure
even if a log type of internal file system is used; it is one thing to
protect against corruption of the last written data but another when
any data can be destroyed.

On Wed, 8 Jun 2016 17:22:38 +0100, you wrote:

>Sounds similar to the issues you encounter with Atmel and some other
>EEPROM/Flash based MCUs when they're not held in reset until VCC becomes
>stable.
>
>http://atmel.force.com/support/articles/en_US/FAQ/Prevent-EEPROM-corruption
>
>Some more info:
>
>http://www.embedded.com/design/prototyping-and-development/4006422/Avoid-corruption-in-nonvolatile-memory
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Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A

[Nick Sayer via time-nuts]

For what it’s worth, the GPS boards I’ve designed for the FEI devices use the 
TPS54[23]31 for the primary 15v supply (which also powers the 5v supply), and 
it has been configured with a hysteretic UVLO with a start threshold above 16 
volts. Additionally, the slow-start is configured for somewhere between 1 and 
10 ms, which I would posit is acceptable. I haven’t actually measured the delay 
between the +15 and +5 supplies, but I don’t have much reason to believe they’d 
be “unreasonably” far apart.

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

I’ve powered up my 5680As a bunch of times with these boards and since 
identifying that one firmware bug in my code where the serial output dropped a 
byte in the tuning command, I haven’t had any trouble.

> On Jun 8, 2016, at 9:22 AM, Clint Jay  wrote:
> 
> Sounds similar to the issues you encounter with Atmel and some other
> EEPROM/Flash based MCUs when they're not held in reset until VCC becomes
> stable.
> 
> http://atmel.force.com/support/articles/en_US/FAQ/Prevent-EEPROM-corruption
> 
> Some more info:
> 
> http://www.embedded.com/design/prototyping-and-development/4006422/Avoid-corruption-in-nonvolatile-memory
> 
> 
> 
> On 8 June 2016 at 16:20, jimlux  wrote:
> 
>> On 6/8/16 6:19 AM, paul swed wrote:
>> 
>>> The units were never intended for a slow ramp
>>> I assume it runs into a meta stable condition
>>> Neither on or off and then corruption
>>> Glad you're can repair them
>>> 
>>> On Tuesday, June 7, 2016, Bob Camp  wrote:
>>> 
>>> 
 
>> Interesting, we just had a similar issue on a circuit here at work..
>> someone slowly brought the supply voltage up on a bunch of DC/DC
>> converters, and some didn't start. This was in initial checkout of a new
>> board.
>> 
>> Switch it on with a bang, and it works just fine.
>> 
>> So for some of these things there's apparently a minimum dv/dt.
>> 
>> I've seen this before with DC/DC converters.. if the voltage drops too
>> low, they draw too much current - because they're basically constant power
>> devices- and the overcurrent trip shuts them down.  There's a delicate
>> interplay between the overcurrent and undervoltage trips,both of which have
>> some sort of time constant, and I suspect that for a lot of circuits, the
>> "slow ramp up of input voltage" isn't something they are designed for.
>> Once it's up and running, when the supply sags, the UV trip works just
>> fine, tripping before the OC trip goes.
>> 
>> 
>> Linear regulators.. they may be not the most efficient thing in the world,
>> but they have a lot less "weird" behavior.  (although I've had linear
>> regulators go into thermally driven oscillation)
>> 
>> 
>> 
>> 
>> 
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>> 
> 
> 
> 
> -- 
> Clint.
> 
> *No trees were harmed in the sending of this mail. However, a large number
> of electrons were greatly inconvenienced.*
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Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A

[David]

Bob Pease recommended saving low gain transistors for operating margin
tests.

On Wed, 8 Jun 2016 18:35:58 +0200, you wrote:

>...
>
>Another way to identify potential start-up problems is to cool down the 
>unpowered oscillator to the minimum operating temperature (or upper operating 
>temperature) and then to apply a slow supply voltage ramp
>
>Bernd
>DK1AG
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Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A

[David]

On Wed, 8 Jun 2016 08:20:45 -0700, you wrote:

>Interesting, we just had a similar issue on a circuit here at work.. 
>someone slowly brought the supply voltage up on a bunch of DC/DC 
>converters, and some didn't start. This was in initial checkout of a new 
>board.
>
>Switch it on with a bang, and it works just fine.
>
>So for some of these things there's apparently a minimum dv/dt.

This problem also occasionally shows up in integrated circuits where a
slow power ramp does not allow the bias circuits to start.  I think
Bob Pease related an instance where this was caused by a missing
connection and capacitive coupling to the substrate was enough to
start the bias circuits but nobody noticed the problem until after it
was in production.

>I've seen this before with DC/DC converters.. if the voltage drops too 
>low, they draw too much current - because they're basically constant 
>power devices- and the overcurrent trip shuts them down.  There's a 
>delicate interplay between the overcurrent and undervoltage trips,both 
>of which have some sort of time constant, and I suspect that for a lot 
>of circuits, the "slow ramp up of input voltage" isn't something they 
>are designed for.  Once it's up and running, when the supply sags, the 
>UV trip works just fine, tripping before the OC trip goes.

These problem seems to crop up more with newer designs.  In old
off-line switching power supply designs that I have studied, most have
a deliberately designed in hard start capability where when an
extended fault condition is detected, the regulator is completely
reset by momentarily shorting the bias supply.  If the fault
continues, then the power supply periodically ticks as it tries to
restart so there is a nice indication of the problem without self
destruction.

The negative input resistance characteristic of switching power
supplies can have another bad result.  Some will continue to operate
at low input voltages drawing excessive current eventually damaging
themselves do to I^2R losses.

Power on reset circuits can have this problem in a different way.  If
power is removed and then reapplied within a short time, an RC circuit
may not discharge enough to retrigger.  Adding a diode to discharge
the capacitor when the supply falls is usually enough to fix this.

Some "universal input" off-line switching power supplies are marked to
run from 90 VAC to 270 VAC but actually cannot because they use an
automatic switching voltage doubler at their input.  If the input is
between the 120 VAC and 240 VAC ranges, they toggle back and forth
until they self destruct.  Luckily these are less common now with
active power factor correction inputs becoming ubiquitous.

>Linear regulators.. they may be not the most efficient thing in the 
>world, but they have a lot less "weird" behavior.  (although I've had 
>linear regulators go into thermally driven oscillation)

Linear regulators with foldback current limiting can have startup
problems with some loads.  Integrated regulators are usually designed
to put out full current as long as secondary breakdown limits are
observed and rely on their thermal protection which is itself designed
to have significant hysterisis to allow for hard starts under any
conditions.  But if the input to output voltage difference is high,
they can fail to start into some loads.
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Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A

[Clint Jay]

Sounds similar to the issues you encounter with Atmel and some other
EEPROM/Flash based MCUs when they're not held in reset until VCC becomes
stable.

http://atmel.force.com/support/articles/en_US/FAQ/Prevent-EEPROM-corruption

Some more info:

http://www.embedded.com/design/prototyping-and-development/4006422/Avoid-corruption-in-nonvolatile-memory



On 8 June 2016 at 16:20, jimlux  wrote:

> On 6/8/16 6:19 AM, paul swed wrote:
>
>> The units were never intended for a slow ramp
>> I assume it runs into a meta stable condition
>> Neither on or off and then corruption
>> Glad you're can repair them
>>
>> On Tuesday, June 7, 2016, Bob Camp  wrote:
>>
>>
>>>
> Interesting, we just had a similar issue on a circuit here at work..
> someone slowly brought the supply voltage up on a bunch of DC/DC
> converters, and some didn't start. This was in initial checkout of a new
> board.
>
> Switch it on with a bang, and it works just fine.
>
> So for some of these things there's apparently a minimum dv/dt.
>
> I've seen this before with DC/DC converters.. if the voltage drops too
> low, they draw too much current - because they're basically constant power
> devices- and the overcurrent trip shuts them down.  There's a delicate
> interplay between the overcurrent and undervoltage trips,both of which have
> some sort of time constant, and I suspect that for a lot of circuits, the
> "slow ramp up of input voltage" isn't something they are designed for.
> Once it's up and running, when the supply sags, the UV trip works just
> fine, tripping before the OC trip goes.
>
>
> Linear regulators.. they may be not the most efficient thing in the world,
> but they have a lot less "weird" behavior.  (although I've had linear
> regulators go into thermally driven oscillation)
>
>
>
>
>
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-- 
Clint.

*No trees were harmed in the sending of this mail. However, a large number
of electrons were greatly inconvenienced.*
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Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A

[Bernd Neubig]

The same problem may appear on some poorly designed crystal oscillators.
Some circuits depend on the spectral component of a fast power-on and will not 
start reliably if the supply voltage is ramped slowly - as can happen if the 
oscillator stage is fed by a voltage regulator with high value capacitor 
blocking at its output.
That is why oscillator testing standards like IEC 60679-1 define the test for 
reliable start-up to consist of a slowly ramping up supply voltage.
Another way to identify potential start-up problems is to cool down the 
unpowered oscillator to the minimum operating temperature (or upper operating 
temperature) and then to apply a slow supply voltage ramp

Bernd
DK1AG
-Ursprüngliche Nachricht-
Von: time-nuts [mailto:time-nuts-boun...@febo.com] Im Auftrag von jimlux
Gesendet: Mittwoch, 8. Juni 2016 17:21
An: time-nuts@febo.com
Betreff: Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A

On 6/8/16 6:19 AM, paul swed wrote:
> The units were never intended for a slow ramp I assume it runs into a 
> meta stable condition Neither on or off and then corruption Glad 
> you're can repair them
>
> On Tuesday, June 7, 2016, Bob Camp <kb...@n1k.org> wrote:
>
>>

Interesting, we just had a similar issue on a circuit here at work.. 
someone slowly brought the supply voltage up on a bunch of DC/DC converters, 
and some didn't start. This was in initial checkout of a new board.

Switch it on with a bang, and it works just fine.

So for some of these things there's apparently a minimum dv/dt.

I've seen this before with DC/DC converters.. if the voltage drops too low, 
they draw too much current - because they're basically constant power devices- 
and the overcurrent trip shuts them down.  There's a delicate interplay between 
the overcurrent and undervoltage trips,both of which have some sort of time 
constant, and I suspect that for a lot of circuits, the "slow ramp up of input 
voltage" isn't something they are designed for.  Once it's up and running, when 
the supply sags, the UV trip works just fine, tripping before the OC trip goes.


Linear regulators.. they may be not the most efficient thing in the world, but 
they have a lot less "weird" behavior.  (although I've had linear regulators go 
into thermally driven oscillation)




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

[jimlux]

On 6/8/16 6:19 AM, paul swed wrote:

The units were never intended for a slow ramp
I assume it runs into a meta stable condition
Neither on or off and then corruption
Glad you're can repair them

On Tuesday, June 7, 2016, Bob Camp  wrote:





Interesting, we just had a similar issue on a circuit here at work.. 
someone slowly brought the supply voltage up on a bunch of DC/DC 
converters, and some didn't start. This was in initial checkout of a new 
board.


Switch it on with a bang, and it works just fine.

So for some of these things there's apparently a minimum dv/dt.

I've seen this before with DC/DC converters.. if the voltage drops too 
low, they draw too much current - because they're basically constant 
power devices- and the overcurrent trip shuts them down.  There's a 
delicate interplay between the overcurrent and undervoltage trips,both 
of which have some sort of time constant, and I suspect that for a lot 
of circuits, the "slow ramp up of input voltage" isn't something they 
are designed for.  Once it's up and running, when the supply sags, the 
UV trip works just fine, tripping before the OC trip goes.



Linear regulators.. they may be not the most efficient thing in the 
world, but they have a lot less "weird" behavior.  (although I've had 
linear regulators go into thermally driven oscillation)





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

[paul swed]

The units were never intended for a slow ramp
I assume it runs into a meta stable condition
Neither on or off and then corruption
Glad you're can repair them

On Tuesday, June 7, 2016, Bob Camp  wrote:

> Hi
>
> Thanks for the heads up !!
>
> It almost sounds like they are doing some sort of “use flash as eeprom”
> trick and not
> quite getting it right. Maybe updating a “how many times turned on”
> counter in that
> memory space.
>
> Bob
>
>
> > On Jun 7, 2016, at 5:22 PM, Skip Withrow  > wrote:
> >
> > We recently had a customer that purchased an FEI FE-5650A (basically a
> > repackage version of the FE-5680A) and reported that it worked for
> several
> > hours, then died.  We promptly sent another unit, and he reported that it
> > died as well.  He had nothing but power hooked to the unit.
> >
> > On return of the first unit, it was examined and found to have corrupted
> > code.  The corrupted code problem was thought to be associated with doing
> > bad things to the serial port (like framing errors), and we still believe
> > this to be the case.  However, the customer said only power was connected
> > to the unit.
> >
> > I was asking some questions about how he was powering the unit, when he
> > said he turned on the power supply (a large HP variable supply) and
> turned
> > the voltage up to +15V (our 5650's are single supply).  Ah hah, slowly
> > ramping the voltage up on these oscillators appears to be a no no.
> >
> > The second oscillator has now been examined and it too was confirmed to
> > have corrupted code.  So, the word of warning is - DO NOT slowly ramp the
> > supply voltage of FE-5680A and FE-5650A oscillators.  I can't say what
> > slowly is, but this guy was good at killing them.  If I get some time I
> may
> > try to repeat the results.
> >
> > My advice was to set the supply at 15V and just turn it off and on.  I
> have
> > not heard from him since.
> >
> > If anyone out there has a 5680A or 5650A that does not lock, the code
> issue
> > is very likely the problem.  I have seen several 5680 units as well as a
> > few 5650 units with this problem.  The good news is that they can be
> > fixed.  I would happily do this for any time-nut that has one if return
> > postage is included with the unit.  The bad news is that we don't know
> the
> > nature of the code problem that trashes the software (stack overflow,
> error
> > handling routine, etc.) so units can only be restored to their original
> > condition that still has the bug in the code.
> >
> > Otherwise, the 5650 and 5680 are great values to get rubidium performance
> > at very reasonable prices.  I have 1000's of hours on them and 100's of
> > power cycles, with a lot of serial port use, so if treated correctly they
> > are reliable units.
> >
> > Regards,
> > Skip Withrow
> > RDR Electronics, Inc.
> >
> > <
> https://www.avast.com/sig-email?utm_medium=email_source=link_campaign=sig-email_content=webmail_term=oa-2322-b
> >
> > Virus-free
> > <
> https://www.avast.com/sig-email?utm_medium=email_source=link_campaign=sig-email_content=webmail_term=oa-2322-b
> >
> > <#DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
> > ___
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Re: [time-nuts] One sure way to kill your FE-5680A or FE-5650A

[Bob Camp]

Hi

Thanks for the heads up !!

It almost sounds like they are doing some sort of “use flash as eeprom” trick 
and not 
quite getting it right. Maybe updating a “how many times turned on” counter in 
that 
memory space.

Bob


> On Jun 7, 2016, at 5:22 PM, Skip Withrow  wrote:
> 
> We recently had a customer that purchased an FEI FE-5650A (basically a
> repackage version of the FE-5680A) and reported that it worked for several
> hours, then died.  We promptly sent another unit, and he reported that it
> died as well.  He had nothing but power hooked to the unit.
> 
> On return of the first unit, it was examined and found to have corrupted
> code.  The corrupted code problem was thought to be associated with doing
> bad things to the serial port (like framing errors), and we still believe
> this to be the case.  However, the customer said only power was connected
> to the unit.
> 
> I was asking some questions about how he was powering the unit, when he
> said he turned on the power supply (a large HP variable supply) and turned
> the voltage up to +15V (our 5650's are single supply).  Ah hah, slowly
> ramping the voltage up on these oscillators appears to be a no no.
> 
> The second oscillator has now been examined and it too was confirmed to
> have corrupted code.  So, the word of warning is - DO NOT slowly ramp the
> supply voltage of FE-5680A and FE-5650A oscillators.  I can't say what
> slowly is, but this guy was good at killing them.  If I get some time I may
> try to repeat the results.
> 
> My advice was to set the supply at 15V and just turn it off and on.  I have
> not heard from him since.
> 
> If anyone out there has a 5680A or 5650A that does not lock, the code issue
> is very likely the problem.  I have seen several 5680 units as well as a
> few 5650 units with this problem.  The good news is that they can be
> fixed.  I would happily do this for any time-nut that has one if return
> postage is included with the unit.  The bad news is that we don't know the
> nature of the code problem that trashes the software (stack overflow, error
> handling routine, etc.) so units can only be restored to their original
> condition that still has the bug in the code.
> 
> Otherwise, the 5650 and 5680 are great values to get rubidium performance
> at very reasonable prices.  I have 1000's of hours on them and 100's of
> power cycles, with a lot of serial port use, so if treated correctly they
> are reliable units.
> 
> Regards,
> Skip Withrow
> RDR Electronics, Inc.
> 
> 
> Virus-free
> 
> <#DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
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