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Attached schematic for the e-Paper driver HAT.

The meaning of the yellow marked part is not clear to me.

enter image description here

Does this mean I can replace 105 (1 μF) with 4.7 μF and use either as available?

The entire schematic can be found here.

ocrdu
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Just doin Gods work
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    You might want to ask from who made the schematics. Or just look at what the e-paper display requires. It can't be deciphered what is meant here with that notation. – Justme Aug 12 '22 at 11:47
  • @Justme Its from waveshare, I didn't find any forum there to ask it. But I'll try again. – Just doin Gods work Aug 12 '22 at 11:57
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    It's 105 and it means 1uF. 150 would mean 15pF, unreasonably low value. – Justme Aug 12 '22 at 12:00
  • @Justme 105/50V seems different than 105|4.7uF. As in 105/50V is it sure, we required only 105 capacitors with 50V capacity. But I have doubt is what would affect if I change 4.7uf where 105 is required (105|4.7uF). Is it possible these small value capacitors can affect the working of PCB for a long time? – Just doin Gods work Aug 12 '22 at 12:06
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    Yes I know what you mean and it can't be answered because we don't know why the caps are marked weirdly and we don't know if the e-paper display module you will use requires 1uF or 4.7uF capacitors to work or even if it makes any difference. But it is possible that it makes a difference. – Justme Aug 12 '22 at 12:10
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    Could it mean a 105 (1uF) in parallel with a 4.7uF? – GodJihyo Aug 12 '22 at 13:42

2 Answers2

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Does this mean I can replace 105 (1 μF) with 4.7 μF and use either as available?

In this specific case yes, though this isn't a standard marking as others have mentioned. It seems to be an artifact of the history of these documents, as I found out. It is NOT a "caps-in-parallel" mark, as JRE's answer suggests.

I've actually been working on miniaturizing this very board recently. Waveshare's documentation is rather confusing, so to figure out what I needed, I consulted:

  • the actual breakout "hat" schematic, including the history of that document on their wiki
  • various versions of eink manuals from their site, including the history of those documents on their wiki
  • Adafruit breakout schematic & Open source design
  • CrystalFontz breakout schmatics

Comparing those, I found that Waveshare has recently bumped up the size of the caps to 4.7µF, but have historically been smaller at 1µF. I'm unimpressed with their document skills.

Here is a snippet of the relevant part of the table that I extracted from these resources when I was trying to decipher this myself, showing marked values and voltage rating:

name eink v3 eink v2 newer hat older hat Adafruit CrystalFontz CF-rating
VSH 4.7/25 105/50 105/50 105/50 1u/25 1u/25 10V~17V
PreVGH 4.7/25 105/50 105/50 105/50 1u/25 1u/50 ~22V
VSL 4.7/25 105/50 105/50 105/50 1u/25 1u/25 -17V~ -10V
PreVGL 4.7/25 105/50 105/50 105/50 1u/25 1u/50 ~ -20V

As you can see, it looks like the newest hat is a mix of eink v3 and the "newer hat" version.

As for me, I ended up using 105/50 (1.0µF 50V rating) as that fit the rest of the project (and I had on hand) and it is working fine for me today.

byteit101
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What does a capacitor marked "105 | 47 μF" mean?

"105 | 47 μF" - a 47 μF electrolytic capacitor with a maximum operating temperature of 105° C.

"105 / 50 V" - a 1 μF 50 V ceramic capacitor.

vu2nan
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