[time-nuts] One sure way to kill your FE-5680A or FE-5650A
nsayer at kfu.com
Wed Jun 8 21:37:41 EDT 2016
For what it’s worth, the GPS boards I’ve designed for the FEI devices use the TPS5431 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 <cjaysharp at gmail.com> 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
> Some more info:
> On 8 June 2016 at 16:20, jimlux <jimlux at earthlink.net> 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 <kb8tq at 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
>> 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)
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> and follow the instructions there.
> *No trees were harmed in the sending of this mail. However, a large number
> of electrons were greatly inconvenienced.*
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts