Late at night, by candle light, Jamie penned this immortal opus:
I have no problem guesstimating reasonable values for the non-criticals, and when needed grab the abacus. Checking them out in LTSpice, they'll work fine. Hey, as JT likes to drone on about, it's "an excercise for the student". Maybe he doesn't think of himself as a student anymore, so should be privileged with all of it worked out.
- YD.
-- Remove HAT if replying by mail.
Sometimes what matters is just the concept, the topology, a feeling for the motion. It's reasonable to play around with stuff like this now and then, before trying to quantify things. At our place, we have really geeky BS sessions, namely a lot of whiteboard scribbling of silly circuits and architectures and packaging ideas. We fight over the best whiteboard markers. Values and dimensions and hardware come later.
Some people have to Spice everything, can't visualize without it. Some people *design* by fiddling with Spice.
It was funny when I posted PDFs of actual production product schematics, with values, and JT demanded .asc files!
-- 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
The LDO didn't have a part number for the MOS device. ...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
If values to an example circuit is what you need for better understanding then I don't think any one would turn you away, here, unless of course, you are throwing specifics that you need exact results for?
Then it would seem that one would be looking for a free designer however, if a concept model needs values I am sure most here that supply sketches will also supply some values, as long as they get to choice their example and not one from those seeking the help.
Then you get the ones that drool, trip, drop their keyboards and mice's just to seize the opportunity to spit out some schematics with full values only to spend the next 2 weeks in correcting the values and design, making a disaster of it. Those usually end up in battle with others that turns into some kind of sex discussion!
Jamie
That stopped you dead in your tracks. So sorry.
--
John Larkin Highland Technology Inc
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
No you're not. Had I assumed a device, you'd have chastised me for erring. Specify the device. If you're not yellow. ...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.
Yellow? It takes Great Manly Courage to type the part number of an SO8 dual mosfet? What a weird geezer you are.
It's on this board.
ZXMN6A25DN8
Why make such a big deal about a trivial discrete LDO?
-- 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
Because I know from experience (*) that your excessive "pre-load" to improve transient response indicates instability at lower currents. You've got too much loop gain.
(*) That latest Rochester chip design had more than 10 voltage domains... one boost switcher, multiple LDO's, several charge-pumps... and the best sequencing control I've ever seen... "body snatchers", a gimmick new to me ;-) ...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.
[snip]
;-) Zetex directly supports PSpice models via both .LIB and .SLB ;-) ...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.
But there aren't any lower currents.
The error amp is an opamp. It could have gain of 1e6 or 1e9 and it wouldn't change the loop response. "Experience" is a poor substitute for understanding.
It's not unstable with a light load. Reference-step response with a 1M load is just about perfectly damped, if a bit slow.
The dump resistor does improve transient-load-step response, but that turns out to not matter. I included it because I didn't know how much PCI Express packets might slam the load currents, but they don't enough to notice.
This is a very minor part of this board, so I did something that I knew would work, and moved on. The board is the central controller for an extreme ultraviolet (EUV) production lithography light source. The scanners are selling for $120e6 each. You don't design chips that would ever need this.
-- 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
Which is it...
"From: John Larkin Newsgroups: sci.electronics.design Subject: Re: Why no depletion mode LDOs? Date: Mon, 07 May 2012 20:42:14 -0700 Message-ID:
Here's a home-brew dual LDO, driving some FPGA stuff.
I gave up a little transient regulation for stability, since my load is fairly constant. The funny looking TPs in the drains are actually PCB trace current shunts, so I can measure load currents.
This board has 11 power rails.
From: John Larkin Newsgroups: sci.electronics.design Subject: Re: Why no depletion mode LDOs? Date: Tue, 08 May 2012 09:09:51 -0700 Message-ID:
Yes, they improved transient response in simulation. I was concerned that PCIe packets would whomp the load currents and wiggle the supplies, but that doesn't seem to be a big deal. I could take them out, but I'd have to write an ECO, and I hate to write ECOs. I suppose that with 1.5 volts in and 1.2 out, I shouldn't be too worried about overshoot in the up direction." ??
I guess we know you have an excuse for every occasion :-) ...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.
What do I need an excuse for? I designed and simulated a dual LDO in under an hour, and it worked as expected. There are 7 PCBs in this controller box, 68 electrical and fiber i/o connectors, and it all works with rev A boards, two cuts and three jumpers total.
You are clearly obcessed, and you are so eager to find fault with a perfectly reasonable, fairly dull, working circuit that you are being stupid. You've done this before.
Make up your mind, moron: killfile me or stalk me. It really doesn't make sense to do both.
-- 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
Clearly I've chosen. Can't you tell ?:-)
Don't you suppose people other than me notice your inconsistent claims?
You claim not to be a geezer, yet you certainly exhibit senility at every turn. ...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.
message
--
In your eyes it's "bad" because it pins you with just a few words to
which you can't reply in kind, so of course you retaliate with
red-herring - but seemingly relevant and authoritative -
irrelevancies.
For you:
Hypocrisy
I know I'm not flawed.
The end justifies the means.
God forgives my lies.
message
Weird old coot.
-- 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
message
Larkin, You should be so proud, you got your name in print yet again O:-) ...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.
r
=A0 =A0 =A0...Jim Thompson
8I doubt if he is being stupid. Unreasonably meticulous is more likely. You push out low volume stuff that works well enough. Jim pushes out high volume stuff that works well enough - but high volume markets support and demand much more meticulous analysis than low volume bespoke circuits. Jim's a journeyman rather than a master-craftsman, but he's always worked on products that are produced in large volume (100k and up) which demand more careful analysis than you can afford.
-- Bill Sloman, Nijmegen
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So, JF loves me and hates me and writes poetry to me, you're simultaneously killfiling me and stalking me, and you're both geezers with serious masculinity hangups and not much to say about electronics. I'm sure glad you both live in wastelands far away from here.
And what was all that idiotic raving about the LDO? I never made any great claims for it, except that it works.
-- 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
Late at night, by candle light, John Larkin penned this immortal opus:
message
Just eyeballing a circuit I can figure out what it does and how it works. I'll add values in the sim if it looks interesting and I want to see where I can take it.
I sketch my ideas both on paper and in spice, calculating values before hitting run. Normally works as expected but occasionally a tweak or two may make an improvement. Those tend to be small, a standard value up or down.
Shotgunning values until it sort of works reveals a lack of understanding.
- YD.
-- Remove HAT if replying by mail.
message
h-I...
Inc
d=A0 =A0 ...Jim Thompson
sneed
Detailed conscious understanding - my sub-conscious shotguns remarkably accurately.
-- Bill Sloman, Nijmegen
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