battery chargers, again
in [Design]
|
From: Joerg on 2 Oct 2009 10:09 John Larkin wrote: > On Thu, 01 Oct 2009 14:06:36 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > > >>> The layout is tedious, because we're optimizing the BGA FPGA routing >>> as we go along... can't just draw the schematic and go forward to the >>> board. >>> >> Ouch. >> >> >>> This *is* rev 30. >>> >> Double-Ouch. I am firing up rev 1 of a really unorthodox cicuit this >> afternoon. Wish me luck, and if you hear a muffled boom north-east from >> you guys ... > > Was that an earthquake or was the Joerg? > No, it worked, must have been an earthquake then ;-) > To calarify, this is rev 30 of the working layout. We haven't fabbed > any boards yet. > > The PCB file will be formally released as 26D150A.PCB, to make rev A > of the product. During layout, we number every iteration. If we change > a net or add a resistor or whatever, we start with schematic > 26S150A29.SCH, change it to 26S150A30.SCH and save that, make the > differences file ECO30, apply that onto pcb 26D150A29.PCB, and save as > 26D150A30.PCB. So we have all the iterations and all the ECO files, > all organized. When we release the schematic and pcb as rev A, we > delete all that working junk. Since we're iterating on the BGA pinout, > we're spinning a lot of ECOs. > > If we go A to B, we start the sequence all over, 26S150B1.SCH etc. > I do it similarly, except adding X1, X2 and so on. And I usually cannot erase the intermediates upon ECO-release because federal agencies often require that a complete design history be kept. So if you do medical, maybe better not to toss it. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 2 Oct 2009 10:41 John Larkin wrote: > On Thu, 01 Oct 2009 14:09:56 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Thu, 01 Oct 2009 13:48:49 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Thu, 01 Oct 2009 13:10:44 -0700, Joerg <invalid(a)invalid.invalid> >>>>> wrote: >>>>> >>>>>> John Larkin wrote: >>>>>>> On Wed, 30 Sep 2009 14:40:06 -0700, Joerg <invalid(a)invalid.invalid> >>>>>>> wrote: >>>>>>> >>>>>>>> John Larkin wrote: >>>>>>>>> On Wed, 30 Sep 2009 16:04:00 -0500, Vladimir Vassilevsky >>>>>>>>> <nospam(a)nowhere.com> wrote: >>>>>>>>> >>>>>>>>>> John Larkin wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>>> I'm working on a smallish board that has four switchers in one corner >>>>>>>>>>> and an ADC that's looking for a 1 nV spectral line in the other, >>>>>>>>>> The 1nV over the background of how many nV/root(Hz) ? >>>>>>>>> About 1. That's our target noise floor. The existing system is >>>>>>>>> ballpark 100 nv/rtHz with huge birdies all over the place. >>>>>>>>> >>>>>>>>> Never let scientists design electronics. >>>>>>>>> >>>>>>>>>>> range >>>>>>>>>>> of interest straddling all the switcher frequencies. >>>>>>>>>> Synchronize the switchers away from the particular frequency of interest? >>>>>>>>> The signals can be all over the place. >>>>>>>>> >>>>>>>>>>> I'm planning on >>>>>>>>>>> spread-spectrum wobulating all the switchers, just in case. >>>>>>>>>> So the dirt will be in band for sure? >>>>>>>>> Yup. Operating range is audio to many MHz, all at once. We digitize at >>>>>>>>> 64 Ms/s and FFT and see what's there. >>>>>>>>> >>>>>>>> How many MHz is "many"? And how much power does the biggest of the >>>>>>>> switchers have to deliver? >>>>>>> 20-ish. And just a couple of watts. I need 5, 3.3, 2.5, 1.8, 1.2, and >>>>>>> -5. All from +12. >>>>>>> >>>>>> Theoretically you could run it at 27.12MHz but that's nasty. If you >>>>>> can't stomach the dissipation of linears then you may be stuck with some >>>>>> spectral dodging scheme like the one I described. We do that in >>>>>> ultrasound sometimes but there I could always get a few clock control >>>>>> lines from some a DSP or FPGA. If I bought the digital and SW guys some >>>>>> beers that night ... >>>>> I've got a couple of switcher eval boards around. Maybe I should fire >>>>> some up and experiment with FMing the switcher freqs and see what that >>>>> does to the spectrum and to the output voltage. >>>>> >>>> But first check the limit values. Or at least try them out with a >>>> potmeter for the frequency set resistor. Easiest would be to have PWM >>>> chips with a sync input. >>> One of my guys wants to have the FPGA synthesize a bunch of FMd clocks >>> and dump that into the reg sync inputs. I was planning to make an >>> analog triangle and squirt a little of it into the pins where the freq >>> set resistors connect. >>> >> For a test your method would be faster. For production, not so much, >> because you'd have to have a servo'ed dual MOSFET in that path. Rohm >> makes them, cheap, if that's the plan at the end. > > > I don't follow that. If I make a simple triangle wave, maybe 0.5 volts > p-p, a few KHz maybe, and run it through a big resistor into the > regulator pin that the timing resistor connects to, it should FM the > switcher's frequency. I'll check all the regs to make sure, but the > Fset pins are usually at DC, and the Fset resistor usually sets a DC > current that the chip uses to make frequency. > On most newer ones it does (simulating one right now). But there are some that do it "NE555-style". Even then you can sometimes get away with current injection but it needs to be vetted for each chip type you are using. > If I have, say, a 1 MHz switcher and push it +-1%, that's 20 KHz p-p, > so I should reduce the amplitude of a 1 MHz birdie by about 20,000:1 > in a 1 Hz BW situation. Not that much in real life, but even 100:1 is > a good number. > Why not go all out and do +/-10% or more? -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 2 Oct 2009 10:59 John Larkin wrote: > On Thu, 01 Oct 2009 14:10:05 -0700, Rich Grise <richgrise(a)example.net> > wrote: > >> On Wed, 30 Sep 2009 20:38:29 -0400, Spehro Pefhany wrote: >>> On Tue, 29 Sep 2009 15:18:12 -0700, the renowned Rich Grise >>>> On Tue, 29 Sep 2009 10:24:57 -0700, John Larkin wrote: >>>>> ... >>>>> I guess several of the posters here, if they left their lights on and >>>>> killed their battery, will always have their car towed and the battery >>>>> replaced. They have no need for jumper cables, and are happy buying >>>>> chargers that only charge batteries that don't need to be charged. >>>>> >>>> Ouch! John, I've never heard you scathe before, but geez! This post >>>> singed my eyebrows! >>>> >>>> Keep it up. >:-> It helps dispel that "leprechaun" image. ;-D >>> Something like this http://www.speff.com/jl.jpg ? >>> >> Eek! Heavens, no! John is cute as a button! It's just that he's about >> 5'6" or so, a bit wiry, and Irish. :-) (I met him face-to-face at a trade >> show in Long Beach a couple of years ago, and picked up some of his >> refrigerator magnets.) :-) >> > > That's what we give out these days, instead of pots of gold. > Just got assembled boards back from AA-PCB yesterday. They threw in a bag of trail mix. Sweet. Needless to say, it was all gone before I had the first scope shots on the server and I wasn't too hungry at dinner time. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 2 Oct 2009 11:08 On Fri, 02 Oct 2009 07:59:11 -0700, Joerg <invalid(a)invalid.invalid> wrote: [snip] >> > >Just got assembled boards back from AA-PCB yesterday. They threw in a >bag of trail mix. Sweet. Needless to say, it was all gone before I had >the first scope shots on the server and I wasn't too hungry at dinner time. Funny what extraneous stuff can end up in a shipment. Recently found a chocolate chip 2-pack in my Amazon order ;-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: Joerg on 2 Oct 2009 11:13
Jim Thompson wrote: > On Fri, 02 Oct 2009 07:59:11 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > > [snip] >> Just got assembled boards back from AA-PCB yesterday. They threw in a >> bag of trail mix. Sweet. Needless to say, it was all gone before I had >> the first scope shots on the server and I wasn't too hungry at dinner time. > > Funny what extraneous stuff can end up in a shipment. Recently found > a chocolate chip 2-pack in my Amazon order ;-) > They seem to do that with all shipments. The one last week also had trail mix in it but arrived at a client so their engineers got to enjoy it. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |