Slow ramp. I've had problems with equipment where some SOB went cheap and the equipment wouldn't boot 90% of the time. I had an entire video editing system at a TV station that was built that way. It took hours to get the damn system working after a power failure, so I modified the units. Since they used all 5 volt logic, I used 555 timers. the boards were already laid out for them, but some penny pinching bastard soldered a cap & resistor over the pads.
'Most of the time' is useless.
If you used a Schmidtt-Obama trigger it would never come out of reset, but it would appologize & blame America. AKA: The can't ever do anything right gate.
Typical crap design.
On a sunny day (Fri, 26 Oct 2012 11:33:16 -0400) it happened "Michael A. Terrell" wrote in :
Works like a charm if you do it right. As you never ever designed anything, your opinion is worth as much as you think about 0bama.
He did supposedly generate a reset with Russia.
mean while the tea party gate would be desperately trying to short the supply hoping something explodes they can blame on the Schmidtt-Obama trigger ;)
-Lasse
Check DigiKey
Product Index > Integrated Circuits (ICs) > PMIC - Supervisors
Select simple reset/por reset, active high, to92 and the voltage you need
Mouser, Microchip, Avnet all have POR chips
Your limiting factor is going to be the TO-92 package. If you can do surface mount your range of options will open up drastically.
-- Chisolm Republic of Texas
There was contact bounce on the mislabeled button, and the logic hung up.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Europeons sure have weird ideas about the U.S. and seem to have no need for facts before expressing an opinion. ...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.
He is based on Mobieus logic. Inside out, and always to one side.
He's collected enough frequent liar miles for a nice long stay at the U.S. Navy's 'Resort' at Guantanamo.
David
You've never seen anything IO designed, becuse it was all under NDA. Crap is crap, and your circuit is crap. Try that with multiple ICs that need reset on powerup. Then it becomes a shit design.
David
It's even a sh*t design with just one IC that needs reliable reset under all conditions.
Hi,
Thanks to John's help, I found a nice little SOT-23 package that will work fine. I wasn't limited to the TO-92 package, I was just hoping for a 3-pin, fairly small package, as the TO-92 would be.
Thanks again guys for your help, Ben
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David
Jan cobbles junk. I worked on mission critical equipment designs. Can you see someone on the ISS, constantly flipping the power switch on a communications system to get it to reboot?
The bullet proof POR has crude and precise references. A bandgap may not be awake yet, so usually you have a crude sensor that flips when there is enough supply voltage to support the operation of the precise reference. Then you compare the bandgap to a crude reference like a VTN, just to make sure it is on its way to waking up, then use a one shot to give the bandgap time to settle. Then the POR uses the precise reference.
There is often a crude lockout that insures the supply is a VTN at least, if not a VTN plus VTP.
Timing circuits will have a parasitic diode from the supply rail to pull the timing cap down to at least a diode drop from ground. This is to insure the supply didn't get slammed to ground then suddenly brought back up again. That is, you want to insure the timing cap has as little residual charge on it as possible.
Somewhere in my repertoire is a bandgap/POR... the POR works by detecting that the bandgap has gone into regulation. ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Then I must be the lucky one, I do PIC, AVR and now looking at some TI stuff at work. All which uses a simple RC reset . They all reset properly.
This is dealing with a supply that is there when switched on, like a battery for example or ready operating source via a switch..
I just think some designs are over killed for such a simple approach that works in most cases. It gets to the point where people just think that if you had to do it once, then it means it's un holy to not ever do it again.
And yes, I explore the options of a design, I just don't assume we need to through in the kitchen sink to start with, just because that is what we did last time and the time before that etc..
I get the idea that some designers are accustom to practices only because it was done elsewhere but never really dig down deep to find out why.
WHat ever..
Jamie
I can't believe what you're saying..
I bet you haven't tried that type of circuit..
It goes to show how people open their mouth and insert..
That circuit is a classic used in many and I mean many of reset circuits.
I'm glad I don't take a good lot of you here seriously..
jamie
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