NO ONE on the group takes you for anything but a fool.
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11 years ago
Power on Reset
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11 years ago
"Experience is a brutal teacher, but you learn. My God do you learn".
Most classic stuff is umm.. less than optimal.
And almost 35,000 part numbers are not required by anyone.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
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11 years ago
What a fool.
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11 years ago
Speff is right. That circuits has lots of hazards.
And that RC time constant is only 47 microseconds!
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
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11 years ago
Thanks for that. I always had the impression there were a few clever tricks in getting to work in a bulletproof manner.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
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11 years ago
Like this...
formatting link
Sequentially checks, VDD>=3*VTH, then VDD>=3V, then a 12V slaved supply is >=11V, then runs a counter/timer for 10ms before releasing the RESETbar (also used for other chips on the board besides itself).
A demonstration of over-kill ;-) ...Jim Thompson
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| James E.Thompson, CTO | mens |
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I love to cook with wine. Sometimes I even put it in the food.
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11 years ago
You didn't notice that I don't have a sagging supply there, also you didn't notice that I don't have any caps on the rail in that circuit.
That circuit works as view in the ASCII.
It just goes to show how people just assume their failures must also be echoing out there on others.
I've used simple RC resets on small uC many times with fixed sources and they work as they should.
Any one in their right mind knows if you're bring up a supply rail with a heavy load on it, you need a slight delay before you initiate the resets. But I knew there were people out there that just assume every one else has also share the same failures in their career and just blow smoke at any one else's success.
Jamie
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11 years ago
What a fool...
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11 years ago
Switch bounce makes it a lot more fun.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
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11 years ago
Late at night, by candle light, Jim Thompson penned this immortal opus:
Seems to be a rather universal trait. You do it all the time.
- YD.
-- Remove HAT if replying by mail.
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11 years ago
When you say "track", it may vary, but it doesn't "track". The threshold will vary by some small percentage of Vcc.
But then many devices have that internally now too, especially the MCUs. I bet that is because they got tired of reports of problems with external reset circuits...
Rick
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11 years ago
David
Why do you argue with him? A long time ago a friend told me, "Never fight with a pig. You only get muddy and it annoys the pig."
Rick
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11 years ago
Say your system powered a laser. Would you really want a laser to glitch?
"Oh hey, sorry about burning that spot in your eye."
POR is very important in some systems.
Ever buy a stereo that thunked the speakers? That is classic power up FAIL.
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11 years ago
Switchers in general and boost converters in particular can give you that slow ramp.
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11 years ago
On a sunny day (Fri, 26 Oct 2012 13:57:58 -0400) it happened Spehro Pefhany wrote in :
David
It is actually not as bad as that Aiwa tape drive.
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11 years ago
On a sunny day (Fri, 26 Oct 2012 22:03:32 -0700) it happened miso wrote in :
That stereo case is different, UNLESS there is a way to isolate the speakers (relays) there usually is a bump. Delayed relay would work. Then it will bump again when powered off (mine does). Learn to quote.
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11 years ago
On a sunny day (Fri, 26 Oct 2012 18:33:43 -0400) it happened Spehro Pefhany wrote in :
Right, that is a consequence of the capitalist system. Soon we will have USSA, (second S stands for 'social'), and there will be only 1 k resistors, and on;ly one type NPN and PNP. Now that challenges design skills.
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11 years ago
Not to mention having to queue for hours just to get your quota of a few dirty corroded 2N2222As per month.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
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11 years ago
The reason I used 555 ICs for reset was that there was no internet, and a TV station trying to get databooks was a sick joke. That editing system used a mixture of linear & switching supplies, depending on the date of manufacture. This was in the '87/'88 timeframe.
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11 years ago
(relays)
Learn not to criticize. This stupid usenet provider makes me truncate quotes most of the time.
There are way to make analog circuits power up cleanly, but good audio equipment puts a relay in series with the output to prevent this thump.
Another thumper can be caused by poorly designed analog muxing, generally in single supply circuits.