<whitequark>
opbolt: current indication for phones?
<whitequark>
if you mean the thing that tells a smartphone to draw 1A or 2A instead of 500mA permitted by the spec, short D+ and D-
<whitequark>
that's it
dandon has joined #qi-hardware
eintopf has quit [Ping timeout: 260 seconds]
eintopf has joined #qi-hardware
wpwrak_ has joined #qi-hardware
wpwrak has quit [Ping timeout: 248 seconds]
eintopf has quit [Ping timeout: 264 seconds]
eintopf has joined #qi-hardware
wpwrak_ has quit [Read error: Connection reset by peer]
wpwrak_ has joined #qi-hardware
wpwrak_ has quit [Ping timeout: 264 seconds]
wpwrak_ has joined #qi-hardware
wpwrak_ has quit [Ping timeout: 264 seconds]
wpwrak_ has joined #qi-hardware
wpwrak__ has joined #qi-hardware
wpwrak_ has quit [Ping timeout: 240 seconds]
sb0 has quit [Quit: Leaving]
eintopf has quit [Ping timeout: 260 seconds]
eintopf has joined #qi-hardware
jow has quit [Ping timeout: 256 seconds]
erichvk__ has quit [Ping timeout: 240 seconds]
sb0 has joined #qi-hardware
jow has joined #qi-hardware
wpwrak__ is now known as wpwrak
<opbolt>
whitequark, yes
<opbolt>
so that tell them its all they can eat? well then thats easier that i thought. i thought i needed special ic to handle off the differences like in fancy 5v usb power supplys.
<opbolt>
off=all
<opbolt>
thx
<whitequark>
opbolt: correction: by the spec, a device can draw 1.5A from a dedicated charging port
<whitequark>
the one with D+/D- shorted
<opbolt>
arr ok. so not 2a but 1.5v is enough
<opbolt>
1.5a isolated dc-dc supplys will be cheaper than 2a ones anyway :)
<whitequark>
it's a bit more complicated than that in practice because vendors implement proprietary extensions
<opbolt>
arr thank much just what i needed
<opbolt>
typical of them
<DocScrutinizer05>
there are like 4 different specs how chargers signal max-current to charging-peripheral. shorting D+/D- is the simplest one. Then there's "apple" method of attaching voltage dividers and thus voltage levels from VBUS to D+ and D-, then you also could add a certain resisitr from ID to GND, and finally there's ENUM (digital)
<whitequark>
yeah that pdf lists them :)
<DocScrutinizer05>
maxim? yes, has some good datasheets and whitepapers covering this madness
<whitequark>
the chips tend to have obnoxious bugs though
<opbolt>
every grateful
<opbolt>
been blowing up china dc-dc +/- dc convters :( i see in exspensive ones on digkey there is a capacitive load column like 2000uf etc... hmm need to read up about this but i noted that on pwoer up the tone board needs more than a 1A as the 2000uf caps charge up then then goes down to under 100ma i think it was. wondering if the very high current demand on power up is what is frying these dc-dc converter boards
<opbolt>
my higher power china dc-dc converter board has suvived but it seams to be adding noise to the audio signal :( so im scanning though digkey or rapid for something better to power these tones boards
paul_boddie has joined #qi-hardware
<opbolt>
arrgh finding +/-15 dc-dc converters with 2000uf capacitive load is not easy!
<opbolt>
most dont go above 500uf... more seaching to do
paul_boddie has quit []
fdcx has joined #qi-hardware
<whitequark>
you could just add an inductor
<whitequark>
to limit inrush current
<whitequark>
that'll also make the output cleaner
wpwrak has quit [Remote host closed the connection]
<opbolt>
the isolation would help with classic ground noise loop thingy type problem i’ve been having too
<opbolt>
that or audio isolators but that risks audio fidelity
<opbolt>
besides ive blow up the last china dc-dc converter i had. some odd thing happened when i connected it to the same power supply as the amp. blow it up, buble os smoke. so i give up. just feel like splashing on fancy thing that will do the job and call it a day.
<opbolt>
worked fine when powered from another battery with dc-dc boost converter outputing 19v. meaning it was ok when i was isolated from amp power supply, which is 30v. max volt of tone board dc-dc convter was 40v. so idk why it blow up. need to learn a new deeper leave of detail to answer that. which means more time...
<opbolt>
still interested to know how i could use an inductor :) i just cant try it out anymore
<opbolt>
spend bloody £40 on many cheap dc-dc converts and a vu meter boards/modules that have gotten blow up. which is just silly. hench spending £25-£40 on a fancy isolated dc-dc is not sounding so bad... mmhhh
<whitequark>
it offers a more complex but much more efficient solution
<whitequark>
with a FET
<whitequark>
fig 5
<opbolt>
"Once the circuit is energized the resistance of the MF72 will decrease rapidly to a very low value, power consumption can be ignored and there will be no effect on normal operating current." ooh i see what ya mean :) i can use a cheaper dc-dc :) with one of these