[Milkymist-devel] PCB layout instructions

[Adam Wang]

Hi,

> 2), 2.2uF(0805)/3.3uF(0805)/4.7uF(0805)/10uF(0805), part --> MLCC; pcb file --
>> polarized 0805
> 6), 100uF(1210), part --> Ceramic chip X5R, pcb file --> polarized 1210
>
> The datasheets say the footprint are 0805/1210. So there should be no problem,
> right?

Correct. I just mentioned and also helped myself to remembered them,
meanwhile I'll directly change them if carefully found chip datasheet
recommended that using Tantalum with low-ESR rather than MLCC etc. Of
course let you know if found.

> For your information, J3 doesn't need to be populated on the production
> devices, it's only meant as an extension for extra audio channels. For this
> reason, we might also not want to populate some parts (R6-R12, C22, R19, C23,
> C25, ...) on the production devices.

Sure, but recommend to populate all them in first trial run for test
all I/O goal.

> J5 is the UART connector. I guess we'll keep it populated as most tinkerers
> will want it. Same for the JTAG connector.

Agreed.

> 5), C46, voltage rating = 500V? This part is still surveying.
>
> No, the voltage rating is 250V only. These capacitors are for ESD protection,
> and IIRC 250V is the rating required to meet FCC/CE standards. Feel free to
> change this as you have more experience than me with certifications.

Well, not more. But I'd like every step being considered and learned
more if time is allowed.

> The resistors you listed:
> http://www.yageo.com/pdf/PYu-RC1206_51_RoHS_L_4.pdf
> have a working voltage of 200V only, but an overload voltage of 400V
> (dielectric breaks over 500V) so I think they should be OK.

Correct! That's why I chose.

> 7), J19, pcb file --> pin1 in wrong position in top side, in correct position
> in bottom side. which side you prefer?
>
> Whatever side. But place the JTAG connector, the UART connector and the SD
> slot (J19) on the same side and close to one another, so that when the board
> is cased we can access all of them with a single door.

ok.

> 10), J8, need confirm on datasheet
>
> What information do you need?

Just need sample to confirm.

> 13), J17, footprint will be change to meet datasheet illustration.
>
> Ok. Btw, as you probably know, "MULTICOMP" is a disguised Farnell noname brand
> which may pose sourcing problems. I still went with their part number on my
> BoM because their footprint is fairly standard and other VGA connectors that I
> checked were compatible.

Right! So I'll use here compatible one. Will update to wiki bom.

> If this is of any help, I can ship you a sample or two.

Yes, I'll provide you my address.
Thanks,
Adam