FEDEVEL
Platform forum

QDrives , 02-11-2025, 08:08 PM

I would run a simulation to see how much power is dissipated.

Sniper2 , 02-11-2025, 08:15 PM

there is no model

Sniper2 , 02-11-2025, 08:16 PM

but with some crude assumptions and gpt i ended up with .25W across 2 0805 resistors

QDrives , 02-11-2025, 08:16 PM

So what is the voltage swing on pin 2 of the primary winding?

Sniper2 , 02-11-2025, 08:18 PM

that pin should stay at Vbus/2 from what i understand and only have the AC over it

Sniper2 , 02-11-2025, 08:19 PM

and the AC over it is 390/2 sine* at 70-100KHz

QDrives , 02-11-2025, 08:20 PM

That DC voltage is over C25. The AC changes goes through R42 and C26.

Sniper2 , 02-11-2025, 08:22 PM

yes

QDrives , 02-11-2025, 08:32 PM

I see that the sine make the losses very low.
My experience is with pulses and snubbers.
I guess with sine wave the capacitor has more time to 'charge'.

Sniper2 , 02-11-2025, 08:34 PM

yea i made my estimate very crudely

Sniper2 , 02-11-2025, 08:35 PM

i am replacing a 1206 with 2 0805 anyway and it is in a area with pour all over

QDrives , 02-11-2025, 08:35 PM

Sniper2 , 02-11-2025, 08:38 PM

qspice nice

Sniper2 , 02-12-2025, 08:39 PM

https://www.reddit.com/r/PrintedCircuitBoard/comments/1inz3fh/review_request_acdc_with_apfc_and_llc_24v_rev_3/

Sniper2 , 02-12-2025, 08:39 PM

i think i got the clearances right this time, mostly cheated and routed on another layer after rearangeing the FETs

Sniper2 , 02-12-2025, 08:46 PM

QDrives , 02-12-2025, 08:57 PM

Unlike one of the comments on placing 2 fuses (for L and N) it is pointless.
A fuse is there for only one reason: overload.
If the weaker fuse is in the neutral, it will blow before the one in the line and still have the circuit under voltage.
If you have leakage/short to earth and line/neutral swapped, either your main circuit breaker goes or the earth leakage goes.

QDrives , 02-12-2025, 09:00 PM

There is are many more comments I can give, but I assume you want to continue and not change too much?

Sniper2 , 02-12-2025, 09:01 PM

well i am still wiling to do a lot of changes if it is needed that is why i didnt bother wth overlay

Sniper2 , 02-12-2025, 09:02 PM

so please rost me sempai 😂

Sniper2 , 02-12-2025, 09:22 PM

QDrives , 02-12-2025, 09:45 PM

The creepage between primary and secondary is not good.
For creepage, the current can flow over the component body in both the opto-coupler and Y cap case.
Use a longer opto-coupler and either a film Y capacitor or multiple SMD in series.

What do you do with the earth connection?


I do want to know where you buy your square drills.

Sniper2 , 02-12-2025, 09:58 PM

squere drills?

Sniper2 , 02-12-2025, 09:59 PM

a if i reffer to the miling slots that is guidline since like i said this is 3rd major rework

Sniper2 , 02-12-2025, 09:59 PM

and rectangles are eassy to work in draft form

Sniper2 , 02-12-2025, 10:00 PM

ill see what i can find regarding the opto

Sniper2 , 02-12-2025, 10:01 PM

i chose that particulat one since TI used it and i sort of had a compensation network more or less from the eval board

Sniper2 , 02-12-2025, 10:01 PM

i have space on the upper side of the PCB for a THT Y cap

Sniper2 , 02-12-2025, 10:01 PM

Earth goes to chasis so basicaly eny mounting hole....

Sniper2 , 02-12-2025, 10:02 PM

tho at home not all sokets are grounded properly so i must be carefull what i do where

QDrives , 02-12-2025, 10:37 PM

Something like this: https://www.digikey.nl/en/products/detail/renesas-electronics-corporation/RV1S2281ACCSP-10YV-KC0/12751112
No need even to have a slot beneath it.

Sniper2 , 02-13-2025, 05:13 AM

Thx, did any other things catch your eyes ?

Sniper2 , 02-13-2025, 07:26 PM

so besides the opto Y cap and creapage is there anything else that cought your eyes?

Sniper2 , 02-13-2025, 07:55 PM

PS that opto is just longer , 300mils and rated fro 5KV while mine was 2.5V i think

Sniper2 , 02-13-2025, 07:56 PM

ok that makes perfect sense

Sniper2 , 02-13-2025, 07:57 PM

my transformer is Insulation Test Voltage VT N1,4 => N2,3 4000 V (AC) so yea a better match for sure

Sniper2 , 02-13-2025, 07:57 PM

HOW DID I MISS THAT I FEEL BLIND

Sniper2 , 02-13-2025, 09:24 PM

with the opta i was useing there is a problem : i used the wrong footprint.....

Sniper2 , 02-13-2025, 09:24 PM

no yea no wander that area looked sus

QDrives , 02-13-2025, 09:45 PM

I did not look much into it.
A good review takes a lot of time.

As for the length of the opto: **if** you need something like 8mm creepage, with the longer one you do not need a board cut out underneath it as it is long enough.
Same goes for a film Y capacitor.
From recollection, 2.5kV is enough.

Sniper2 , 02-13-2025, 09:45 PM

yea my opto was 8.1mm

Sniper2 , 02-13-2025, 09:46 PM

but footprint was wrong with like 3-4mm

Sniper2 , 02-13-2025, 09:46 PM

bug OPS on my side

Sniper2 , 02-13-2025, 09:46 PM

Y cap is easy swap

Sniper2 , 02-13-2025, 09:46 PM

THX anywa since just pointing at odd stuff is enough since it makes me focus on something

QDrives , 02-13-2025, 09:46 PM

I have seen to many shapes, so would not know.

Sniper2 , 02-13-2025, 09:52 PM

BTW should i remove the folder mask over the isolation barier? aka the 8mm gap

Sniper2 , 02-13-2025, 09:52 PM

or not?

QDrives , 02-13-2025, 10:11 PM

No. Leave the solder mask.

Sniper2 , 02-14-2025, 05:25 AM

Ok thx