I really like the TPS5 family of tiny little switchers, but their Spice models are, to be kind, absurd garbage. The first switcher on our board simulates input power of 12 volts * 9 tera-amps. We're well along on pcb layout of a new delay generator, but I really want more confidence that everything will work first pass. So in parallel we're prototyping the switchers. https://www.dropbox.com/sh/gxvkrjd0fr7peft/AACsNPaUkMTtTOAVcS1qeJAna?dl=0 I added SMB coax connectors to the outputs. It's hard to measure switcher noise and ripple with a scope probe. The PCB has no solder mask on vias, which makes probing and hacking easier. One can't do that on a dense board or it will make a zillion shorts. I like those cute Amazon banana jack things. They are almost free. My management (ie, The Brat) won't let me use Amazon stuff in production, but I can sneak them onto prototypes that won't be sold.
testing the TI switchers
Started by ●November 10, 2022
Reply by ●November 11, 20222022-11-11
John Larkin wrote:> I really like the TPS5 family of tiny little switchers, but their > Spice models are, to be kind, absurd garbage. The first switcher on > our board simulates input power of 12 volts * 9 tera-amps. > > We're well along on pcb layout of a new delay generator, but I > really want more confidence that everything will work first pass. So > in parallel we're prototyping the switchers. > > https://www.dropbox.com/sh/gxvkrjd0fr7peft/AACsNPaUkMTtTOAVcS1qeJAna?dl=0 > > > >I added SMB coax connectors to the outputs. It's hard to measure> switcher noise and ripple with a scope probe.Yup. We sprinkle U.FL footprints on our boards for the same reason. They're cheap and small, and make probing a breeze.> > The PCB has no solder mask on vias, which makes probing and hacking > easier. One can't do that on a dense board or it will make a zillion > shorts. > > I like those cute Amazon banana jack things. They are almost free. > My management (ie, The Brat) won't let me use Amazon stuff in > production, but I can sneak them onto prototypes that won't be sold.We use Aliexpress connectors and stuff in POCs and suchlike. Since Hammond and Bud jacked up the prices on their extruded cases, we're going to Aliexpress extrusions plus laser-cut end plates from SendCutSend. 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
Reply by ●November 11, 20222022-11-11
On Fri, 11 Nov 2022 13:17:11 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>John Larkin wrote: >> I really like the TPS5 family of tiny little switchers, but their >> Spice models are, to be kind, absurd garbage. The first switcher on >> our board simulates input power of 12 volts * 9 tera-amps. >> >> We're well along on pcb layout of a new delay generator, but I >> really want more confidence that everything will work first pass. So >> in parallel we're prototyping the switchers. >> >> https://www.dropbox.com/sh/gxvkrjd0fr7peft/AACsNPaUkMTtTOAVcS1qeJAna?dl=0 >> >> >> >> >I added SMB coax connectors to the outputs. It's hard to measure >> switcher noise and ripple with a scope probe. > >Yup. We sprinkle U.FL footprints on our boards for the same reason. >They're cheap and small, and make probing a breeze. > >> >> The PCB has no solder mask on vias, which makes probing and hacking >> easier. One can't do that on a dense board or it will make a zillion >> shorts. >> >> I like those cute Amazon banana jack things. They are almost free. >> My management (ie, The Brat) won't let me use Amazon stuff in >> production, but I can sneak them onto prototypes that won't be sold. > >We use Aliexpress connectors and stuff in POCs and suchlike. Since >Hammond and Bud jacked up the prices on their extruded cases, we're >going to Aliexpress extrusions plus laser-cut end plates from SendCutSend. > >Cheers > >Phil HobbsWe did our own extrusions to replace the dreadful Hammond stuff. http://www.highlandtechnology.com/DSS/J736DS.shtml http://www.highlandtechnology.com/DSS/T130DS.shtml We laser them to do the artwork. We thought we were removing the anodize, but I think we're just removing the dye. It's still non-conductive. We do need to be careful that everything is solidly grounded. Undercut flathead screws cut into anodized countersinks pretty well.
Reply by ●November 11, 20222022-11-11
On Fri, 11 Nov 2022 13:10:40 -0800, John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:>On Fri, 11 Nov 2022 13:17:11 -0500, Phil Hobbs ><pcdhSpamMeSenseless@electrooptical.net> wrote: > >>John Larkin wrote: >>> I really like the TPS5 family of tiny little switchers, but their >>> Spice models are, to be kind, absurd garbage. The first switcher on >>> our board simulates input power of 12 volts * 9 tera-amps. >>> >>> We're well along on pcb layout of a new delay generator, but I >>> really want more confidence that everything will work first pass. So >>> in parallel we're prototyping the switchers. >>> >>> https://www.dropbox.com/sh/gxvkrjd0fr7peft/AACsNPaUkMTtTOAVcS1qeJAna?dl=0 >>> >>> >>> >>> >>I added SMB coax connectors to the outputs. It's hard to measure >>> switcher noise and ripple with a scope probe. >> >>Yup. We sprinkle U.FL footprints on our boards for the same reason. >>They're cheap and small, and make probing a breeze. >> >>> >>> The PCB has no solder mask on vias, which makes probing and hacking >>> easier. One can't do that on a dense board or it will make a zillion >>> shorts. >>> >>> I like those cute Amazon banana jack things. They are almost free. >>> My management (ie, The Brat) won't let me use Amazon stuff in >>> production, but I can sneak them onto prototypes that won't be sold. >> >>We use Aliexpress connectors and stuff in POCs and suchlike. Since >>Hammond and Bud jacked up the prices on their extruded cases, we're >>going to Aliexpress extrusions plus laser-cut end plates from SendCutSend. >> >>Cheers >> >>Phil Hobbs > >We did our own extrusions to replace the dreadful Hammond stuff. > ><http://www.highlandtechnology.com/DSS/J736DS.shtml> > ><http://www.highlandtechnology.com/DSS/T130DS.shtml> > >We laser them to do the artwork. We thought we were removing the >anodize, but I think we're just removing the dye. It's still >non-conductive. > >We do need to be careful that everything is solidly grounded. Undercut >flathead screws cut into anodized countersinks pretty well.You might consider using Noalox on the joint: .<https://www.idealind.com/us/en/shop/30-026.html> Joe Gwinn
Reply by ●November 12, 20222022-11-12
On Friday, November 11, 2022 at 1:10:53 PM UTC-8, John Larkin wrote:> We do need to be careful that everything is solidly grounded. Undercut > flathead screws cut into anodized countersinks pretty well.They make a reliable ground if you use these washers <https://www.mcmaster.com/washers/countersunk-external-tooth-lock-washers/> making a gas-tight contact. For power safety ground, of course, you want a connection OTHER than a fastener that can be loosened from outside the box (like, a rivet, or externally-unreachable screwdown).
Reply by ●November 12, 20222022-11-12
On Fri, 11 Nov 2022 23:23:47 -0800 (PST), whit3rd <whit3rd@gmail.com> wrote:>On Friday, November 11, 2022 at 1:10:53 PM UTC-8, John Larkin wrote: > >> We do need to be careful that everything is solidly grounded. Undercut >> flathead screws cut into anodized countersinks pretty well. > >They make a reliable ground if you use these washers ><https://www.mcmaster.com/washers/countersunk-external-tooth-lock-washers/> >making a gas-tight contact. For power safety ground, of course, >you want a connection OTHER than a fastener that can be loosened from outside >the box (like, a rivet, or externally-unreachable screwdown).I could get some to try, but I think they would look klunky on an external end plate. People already are whining about the undercut flatheads, which extend maybe 20 mils above the panel. These little boxes are powered from warts and usually bolted down, so we don't need a big ground lug.
Reply by ●November 12, 20222022-11-12
On Fri, 11 Nov 2022 22:30:40 +0100, olaf <olaf@criseis.ruhr.de> wrote:>John Larkin <jlarkin@highlandsnipmetechnology.com> wrote: > > > >https://www.dropbox.com/sh/gxvkrjd0fr7peft/AACsNPaUkMTtTOAVcS1qeJAna?dl=0 > >I am impressed by the LM3880. I did not know that something >like this exist.Yes, it was a real find. In my circuit, it trips when the +1v switcher hits +0.5, and then it sequences the rest every 30 ms. The Zynq FPGA wants to be, possibly needs to be, supply sequenced. The SRST# output un-resets everything and starts the boot process. I'd prefer a slower version, but the 30 ms one was available. R103 discharges the +1 rail during brownouts, to make sure the sequencer runs when power returns. U15 guarantees a minimum brownout time to let stuff discharge. Ideally no brownout or fumbling with a wall-wart can hang the system up.> > >I added SMB coax connectors to the outputs. It's hard to measure > >switcher noise and ripple with a scope probe. > >Tek offers a TPR1000/4000 to help you out. :) > >OlafThere's still the ground clip. A coax gives a really solid ground from the board to the scope, or to a preamp to see the tiny stuff. With probes, you run out of hands too. SMB connectors are handy on important things like clocks, so you can poke other things with probes. https://www.dropbox.com/s/8oefk1v8avr6l7a/Probe_Slips.jpg?raw=1
Reply by ●November 12, 20222022-11-12
John Larkin wrote:> On Fri, 11 Nov 2022 23:23:47 -0800 (PST), whit3rd <whit3rd@gmail.com> > wrote: > >> On Friday, November 11, 2022 at 1:10:53 PM UTC-8, John Larkin wrote: >> >>> We do need to be careful that everything is solidly grounded. Undercut >>> flathead screws cut into anodized countersinks pretty well. >> >> They make a reliable ground if you use these washers >> <https://www.mcmaster.com/washers/countersunk-external-tooth-lock-washers/> >> making a gas-tight contact. For power safety ground, of course, >> you want a connection OTHER than a fastener that can be loosened from outside >> the box (like, a rivet, or externally-unreachable screwdown). > > I could get some to try, but I think they would look klunky on an > external end plate. People already are whining about the undercut > flatheads, which extend maybe 20 mils above the panel. > > These little boxes are powered from warts and usually bolted down, so > we don't need a big ground lug. >So you're using a thin head that's flat top and bottom to cut into the conical surface? ("Flat head screw" means countersunk in my lexicon, as opposed to (for example) the painted oval head things that come packaged with outlet plates from Home Depot.) 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
Reply by ●November 12, 20222022-11-12
On Saturday, November 12, 2022 at 7:42:57 AM UTC-8, John Larkin wrote:> On Fri, 11 Nov 2022 23:23:47 -0800 (PST), whit3rd <whi...@gmail.com> > wrote: > >On Friday, November 11, 2022 at 1:10:53 PM UTC-8, John Larkin wrote: > > > >> We do need to be careful that everything is solidly grounded. Undercut > >> flathead screws cut into anodized countersinks pretty well. > > > >They make a reliable ground if you use these washers > ><https://www.mcmaster.com/washers/countersunk-external-tooth-lock-washers/>> I could get some to try, but I think they would look klunky on an > external end plate. People already are whining about the undercut > flatheads, which extend maybe 20 mils above the panel.With a good adjustable stop, you could countersink the endplates for your choice of extension; 2 mils above, flush, two mils below... <https://www.mscdirect.com/product/details/32243370>
Reply by ●November 12, 20222022-11-12
On Sat, 12 Nov 2022 14:25:30 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>John Larkin wrote: >> On Fri, 11 Nov 2022 23:23:47 -0800 (PST), whit3rd <whit3rd@gmail.com> >> wrote: >> >>> On Friday, November 11, 2022 at 1:10:53 PM UTC-8, John Larkin wrote: >>> >>>> We do need to be careful that everything is solidly grounded. Undercut >>>> flathead screws cut into anodized countersinks pretty well. >>> >>> They make a reliable ground if you use these washers >>> <https://www.mcmaster.com/washers/countersunk-external-tooth-lock-washers/> >>> making a gas-tight contact. For power safety ground, of course, >>> you want a connection OTHER than a fastener that can be loosened from outside >>> the box (like, a rivet, or externally-unreachable screwdown). >> >> I could get some to try, but I think they would look klunky on an >> external end plate. People already are whining about the undercut >> flatheads, which extend maybe 20 mils above the panel. >> >> These little boxes are powered from warts and usually bolted down, so >> we don't need a big ground lug. >> > >So you're using a thin head that's flat top and bottom to cut into the >conical surface? > >("Flat head screw" means countersunk in my lexicon, as opposed to (for >example) the painted oval head things that come packaged with outlet >plates from Home Depot.)Flat head is the correct term for the kind that goes flush in a countersunk (conical) hole. The oval things have "oval" heads. Here is the rest of the chart: .<https://www.boltdepot.com/fastener-information/type-chart.aspx> The bible for all such things is "Machinery's Handbook", first edition published in 1914, and continuously ever since. Current is the 31st edition. .<https://books.industrialpress.com/9780831137311/machinerys-handbook-toolbox/> There are lots of used copies available for small dollars in such as used tool stores (and eBay). Older editions are perfectly serviceable, especially for a small shop with manual machines. I use the 27th edition, and also the 25th edition. The original size was meant to fit into the upper center drawer of a standard machinist's 8-drawer toolbox, such as that made by Kennedy. This size is now known as a "toolbox" edition, and it's larger version is a "big-print" edition. Joe Gwinn
