Looks like a nice part, thanks. Have you used it?
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Lotta stuff! How many layers?
I use some 8 w/mk stuff from 3G. About the color and consistancy of used chewing gum.
How about an LTC3803 autotransformer boost followed by a linear reg with a current limit? The boost switcher would quit switching below 24 volts out. Above that, it would be programmed to keep maybe 10 volts across the linear reg. Since my load is nominally 100 ohms (50 mine,
50 the customer's) the worst-case linear reg is when we make 12 volts into 100 ohms, which only dissipates 1.4 watts in the linear reg. At 100 volts and 140 mA load, it also dissipates 1.4 watts.I can use a SOT-89 depletion fet in the linear regulator. That solves some gate drive problems. It resembles an old tube regulator circuit.
Of course, the customer can short my output too.
-- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Yikes. I've seen some synchronous switchers that seemed optimized to turn their substrate diodes into drift-step-recovery diodes. They freaked out the front ends of opamps six inches away.
I like MAX809 for powerup reset. Sometimes I have it check a couple of voltages and a thermistor.
-- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Six, with blind vias so that we can put noncritical analogue stuff on the back side of the SMPS box. On this board that's the TEC driver stuff, since we can use big bypass caps on the TEC leads with no worries. The ultraquiet laser driver section goes opposite the MCU, which doesn't cause any magnetic worries.
Even though we're pulling amps from a +5V supply, there's no schmutz on the diode laser bias even with zero dB attenuation on the SA and a 10-Hz resolution bandwidth. The laser bias current is way sub-Poissonian, so that's pretty indicative. Mr. Faraday was a very smart man, as others have previously observed. ;)
Same sort of stuff here. We just need it not to flow under thermal cycling, to prevent gaps opening up. (That is, it has to be a soft solid and not a thick liquid, so that we can maintain a nonzero preload.)
Could get a bit toasty if all five channels are doing that at once.
I've never done a flyback supply, but the suggested application circuit looks like an EMI failure waiting to happen. How about the Vlad Memorial antiseptic converter, that does its snubbing by returning turn-off transient to the output?
Yeah, that's a problem.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
I remember. LM3103 or something?
This is for the next step in the process, when the MCU has told the SMPS to start but it hasn't come up yet, and for those unfortunate occasions when something happens to the lower-voltage rail--the MCU switches back to running of +24 with no muss, fuss, reboots, etc.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
I reserve the right to burn his fingers, to teach him a lesson.
Well, I did that to myself, on a hot SMA connector.
It gets pretty hot trying to put 44 volt pulses into a 1 ohm load, without any cooling.
-- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
I am not sure how much current you can get out of a voltage doubler, but maybe you regulate to some point and then double. you could probably find a way to regulate it even
I lied. I double-checked the schematic, and it turns out that there's no AOZ inverter on this board, but the two others do fit nicely under that 1.5 square inch shield.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Computer power supplies use a doubler when run from 1120 VAC. Some put out over a KW. That is over eight amps through the doubler at the input.
-- Never piss off an Engineer! They don't get mad. They don't get even. They go for over unity! ;-)
Half of that, or to be more exactly up to 65V: LT8620. Can supply 2A. I used it for several avionics products where supply surge up to 60V are common. Got it quiet enough with conducted emissions, too.
Yikes, six bucks in reels. Looks like a nice part though.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
There a circuit, flyback converter driving a voltage doubler, that in theory outputs zero to infinite voltage. Well, sort of theory.
-- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Only if you can find a flyback transformer with no inter-winding capacitance.
The energy stored in the inductor is finite, and once you have used all of it to charge the interwinding capacitance, you've got as much voltage swing as you can get. The voltage doubler is just a bit more capacitance you have to charge.
The "sort of theory" involved seems to be the sort that's imperfectly understood.
-- Bill Sloman, Sydney
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