<DocScrutinizer05>
hah, step up. always has a virtual diode forwarding input thru choke to output
<DocScrutinizer05>
those critters also don't really current-limit. You can pull mega-amps from output at input voltage
<wpwrak>
i'm sure that, for a few picoseconds, you can :)
<DocScrutinizer05>
hehe, hardly, the inductance of the pin is too high
<wpwrak>
but then there's the parasitic capacitance. a while 5 pF, all yours to burn ;-)
<wpwrak>
s/while/whole/
<qi-bot>
wpwrak meant: "but then there's the parasitic capacitance. a whole 5 pF, all yours to burn ;-)"
<DocScrutinizer05>
yeah, the block diagram of the chip *suggests* it has a switch that cuts out output. But that isn't meant to work that way, and you don't know what P/N-gaps are *really* on the die
<DocScrutinizer05>
could even be OVP or clamp diodes
<DocScrutinizer05>
> >In conventional synchronous step-up converters, a con -duction path exists from input to output through th ebackgate (body diode) of the P-channel MOSFET durin gshutdown. Special application circuitry can disconnect th eload from the battery during shutdown (see Figure 1).<<
<DocScrutinizer05>
it's all already there ;-)
<DocScrutinizer05>
and i'm once again lucky that my uneducated blbla was in line with the explanation in the datasheet ;-P
<wpwrak>
ah yes, that's where they were hiding it. thanks :)
<wpwrak>
hehe ;-)
<wpwrak>
interesting that they mix FET and BJT, instead of just using two FETs
<DocScrutinizer05>
BJT?
<DocScrutinizer05>
aah
<wpwrak>
Bipolar Junction Transistor
<DocScrutinizer05>
more interesting are the 2%..3% higher efficiency with an external schottky
<wpwrak>
yeah, burning 1.5 uA in the transistor is still about an order of magnitude below that
<DocScrutinizer05>
wtf is the deal with FB?
<DocScrutinizer05>
or rather, with R1, R2
<DocScrutinizer05>
are they for decoration?
<wpwrak>
it's for the adjustable version
<wpwrak>
i picked the fixed version, which has them inside the chip
<DocScrutinizer05>
weird, they say >>The AAT1217 has two fixed output voltage options: 3.3 Vand 5V. An internal resistor divider is connected to th eFB pin inside the package which eliminates the need fo rexternal feedback resistors.<< Still they mention the external R1/R2 dimensioning for exactly those two output voltages. And use the only values for R1/R2 in the application note that doesn't make any sense at all
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<DocScrutinizer05>
this seems pretty important to me: >>In applications where th einput power source lead inductance cannot be reduce dto a level that does not affect the converter perfor -mance, a high ESR tantalum or aluminum electrolyti ccapacitor should be placed in parallel with the low ESR ,ESL bypass input ceramic capacitor. The introduction o fthe high ESR capacitor dampens the high Q network an dstabilizes the AAT1217.<<
<DocScrutinizer05>
though they write it's usually not a problem for PCB with their short traces, I'd rather not rely on it, particularly when using a CR2032 as input, and when shielding and EMI is a concern
<wpwrak>
well, someone may prefer to buy just the adjustable version and add cheap resistors.
<DocScrutinizer05>
ooh there are different versions?
<wpwrak>
see page 12 :)
<DocScrutinizer05>
AAAH I see
<DocScrutinizer05>
-1.2 -3.3
<wpwrak>
1.2, confusingly, isn't 1.2 V but 1.2 A ;-)
<DocScrutinizer05>
duh, 1.2Ampere?
<DocScrutinizer05>
that's.... o.O
<wpwrak>
well, or maybe MHz. can be either.
<wpwrak>
in any case, it's not V ;-)
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<wpwrak>
at least it's not gigaparsecs per pound force :)
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<DocScrutinizer05>
ok, finished my "breakfast"
<DocScrutinizer05>
(iow closed the pdf-reader)
<wpwrak>
tasty little pixels :)
<DocScrutinizer05>
yeah, I wonder if it was Wolfgang who minted the "eats datasheets for breakfast"
<wpwrak>
anyway, i need to see if the display will actually draw the advertized current in sleep mode. maybe i just got that wrong. if it's happy with 1-2 uA, then i won't bother trying to beat that
<wpwrak>
:)
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<DocScrutinizer05>
beware of dangling floating inputs
<DocScrutinizer05>
they easily cause excess quiescent
<wpwrak>
i may have held the chip in reset. could be that it didn't like that.
<DocScrutinizer05>
(sorry for mentioning it)
<DocScrutinizer05>
yep, sure
<wpwrak>
while (reset) try_to_get_out();
<DocScrutinizer05>
reset pulls low quite a number of internal reset inputs
<wpwrak>
i usually try all the likely combinations, see which ones actually result in the lowest current. sometimes, doing it "wrong" works best.
<DocScrutinizer05>
so it can be _very_ power hungry
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<DocScrutinizer05>
wpwrak: in austria we can't finance the Neo900 with down payments. It's forbidden to accept money from non-bank persons/entities and pay interest for it. Only banks may do that :-o I guess austria is quite silly a country
<roh>
DocScrutinizer05: it gets much more complicated than that ;)
<DocScrutinizer05>
even more funny, it's not the private person that's lending the money and accepts the interest on top of payback who's getting sued but the one who takes the money
<roh>
DocScrutinizer05: remember the tax stuff for gta01?
<DocScrutinizer05>
no
<DocScrutinizer05>
been ante Joerg
<roh>
shipping from california.. means: sales tax depends to which us state or country you sell to
<DocScrutinizer05>
ooh
<roh>
but when you ship from california to california... its gets more complicated.. then there is sales tax depending on the district.
<DocScrutinizer05>
yeah, USA are also weird
<roh>
total mindfuck. i typed in dozends of different tax levels into that stuff
<DocScrutinizer05>
eeew
<roh>
and it changed multiple times. thats why we went shopify later...
<DocScrutinizer05>
shopify?
<roh>
because there was also the issue of different shipping prices depending on the wherefrom, whereto etc
<roh>
DocScrutinizer05: webshop-application-logic and maintainance service
<DocScrutinizer05>
mhm
<DocScrutinizer05>
well, I never looked into that ;-P
<roh>
they run the shop and the servers, and take care of such nasty details... and stuff like ups shipping price calculation... i nearly went mad till i found that
<DocScrutinizer05>
or actually I might have done, at a time when GTA01 wasn't available anymore
<roh>
and that was before i went checking out how to accept a creditcard internationally
<DocScrutinizer05>
ouch
<DocScrutinizer05>
steer clear of credit cards
<roh>
not possible when you want to sell in the 3rd world
<DocScrutinizer05>
yep
<roh>
;)
<DocScrutinizer05>
It still strikes me funny that in Austria no money lending as long as not one of the 2 entities is a bank
<DocScrutinizer05>
dumbnuts
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<whitequark>
use bitcoin !
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<viric>
damn bitcoin
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<wpwrak>
use silk road ! ;-)
<wpwrak>
DocScrutinizer05: i didn't spend enough time in austria to know about such details :) but i wonder whether this actually applies to you - if you sell something in .de, are you obliged to find out whether there are local .at laws that affect it ?
<wpwrak>
DocScrutinizer05: besides, is this really an "interest" ? i can't imagine that discounts and such are forbidden in austria.
<viric>
wpwrak: hm what was that silk road?
<viric>
I think I recently saw it, and I forgot all again
<viric>
aaah yes, it was in the news.
<viric>
"FBI seized over 26,000 BTC"
<viric>
I imagine my parents hearing that in the news... fun.
<wpwrak>
;-)
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<larsc>
how is that worse than s/BTC/USD/ ?
<wpwrak>
i think it's 1 BTC = 150 USD or such, so it's about 150 times worse
<whitequark>
I think the guy got around $60m or something, in total
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