Tuesday, September 20, 2011

PSoC3 Custom Board - Schematics

The schematics are the first real design I've done for this project.Based on the reference design(in the datasheet),I've come up with a basic schematic for the design.I'll post it here after I figure out what power level I want to go with.

(A recap of the power dilemma, Which Source? - USB,DC Power Jack,Header ..all 3 ? and Which Power level? 5,3.3 or a custom level? ..all 3?)

About the USB connections,whats the simplest way,while not abusing specs? I've seen a range of designs,some with direct connections,some with just resistors on the D+,D- lines,while most use the 3.6V zeners too.But all production level designs(the PSoC kits,mbed and more) use USB Transient suppressors(like the TI's SN65220) chips with some more passive parts.

While that does sound exotic to me,its there for a solid reason.Again,I find myself torn between keeping it simple and cheap,and doing the right thing.

Update 21/9/11 - Based on U2's inputs on the cypress forums,I've added only 2 22ohm resistors on each of the D+,D- lines since the PSoC has an internal regulator to stick to 3.3V on them.

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