// #eevblog — 2021-03-14
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21:58:59 Topic Is: Official IRC channel of the EEVblog - www.eevblog.tv
21:58:59 Set By: (Halcyon) on: Fri Jan 24 20:18:27 2020
21:58:59 <hsn> im thinking this might solve it ? https://snipboard.io/C3QB2T.jpg
21:58:59 <T3sl4> who drew the fucking mosfet
21:58:59 <hsn> T3sl4, the fucking hsn
21:58:59 <hsn> lol
21:58:59 <hsn> why
21:58:59 <T3sl4> is it supposed to be N or P
21:58:59 <T3sl4> it shows a P source follower
21:58:59 <T3sl4> which doesn't make sense already
21:58:59 <hsn> P
21:58:59 <T3sl4> but the body diode is shorting it out anyway
21:58:59 <hsn> ah
21:58:59 <hsn> T3sl4, u mean it should be this: https://snipboard.io/zuqOWM.jpg
21:58:59 <T3sl4> ye
21:58:59 <hsn> i copied a "n mosfet" and just changed the arrow of gate ..
21:58:59 <hsn> because i suck .. :D
21:58:59 <T3sl4> you can just remove the body diode, cuz thats what the substrate diode already is
21:58:59 <hsn> T3sl4, these ppl draw it
21:58:59 <hsn> https://www.diodes.com/assets/Datasheets/DMP4065S.pdf
21:58:59 <hsn> just to make dummies like me understand its there ?
21:58:59 <T3sl4> probably
21:58:59 <T3sl4> sometimes its drawn as a zener to suggest avalanche handling i suppose
21:58:59 <hsn> i like that its there because on other sheet its being used for reverse protection start
21:58:59 Quit: Andre ([email protected]) [EOF from client]
21:58:59 Join: Andre ([email protected]) to #EEVblog
21:58:59 <EEVBlog> New EEVBlog Tweet: I'm pretty darn sure they completely removed the acceleration/deceleration graph display from the new UI firmware. That sucks.
21:58:59 <hsn> T3sl4, im thinking of it like this: https://snipboard.io/fGXax2.jpg
21:58:59 <hsn> at time = 0
21:58:59 <T3sl4> right, it's a short circuit, not a limiter
21:58:59 <hsn> no .. thats different circuit
21:58:59 <hsn> oh .. yeah .. u mean .. this: https://snipboard.io/20iOmY.jpg ?
21:58:59 <hsn> now that u mention it .. there will be lots of "switching at 1.25A current" .. which will destroy the mosfet right ??!
21:58:59 <T3sl4> thats alright, yeah
21:58:59 <T3sl4> tho U8 needs compensation
21:58:59 <T3sl4> or latching if it's supposed to switch
21:58:59 <hsn> is compensation = delay .. to make less switching .. in this context ?
21:58:59 <T3sl4> comp if opamp
21:58:59 <hsn> so i can make it "latch" and reset comes from mcu .. or .. latch and reset by time ..
21:58:59 <hsn> just to avoid mosfet heating ..
21:58:59 <T3sl4> 1.25A isn't much, iunno if you intend to dissipate that continuously or what
21:58:59 <hsn> its supposed to .. prevent output shorts
21:58:59 <hsn> the software can read that comparator result and turn off the output .. but what if software is shit .. its no good ..
21:58:59 <hsn> then it will be continuesly .. "turning on and off" the mosfet ..
21:58:59 <T3sl4> what if the comparator is spazzing out at like a MHz
21:58:59 <hsn> yeah thats why i should latch right ?
21:58:59 <T3sl4> can be as simple as +feedback capacitance to make a multivibrator, or the full canonical form with a flip-flop and delay timer
21:58:59 Join: Kuschelpony ([email protected]) to #EEVblog
21:58:59 <hsn> yeah will try that capacitor charge delay vibrator thingy
21:58:59 <hsn> i would guess less BOM with the capacitor thingy
21:58:59 <hsn> BOM items ..
21:58:59 Quit: Kuschelpony ([email protected]) [Connection closed]
22:48:18 Quit: Halcyon ([email protected]) Ping timeout: 121 seconds
23:13:32 <EEVBlog> New EEVBlog Tweet: Should I dare? https://t.co/wGSj71e0Ja
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