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Electronics => Projects, Designs, and Technical Stuff => Topic started by: NivagSwerdna on August 01, 2020, 04:46:11 pm

Title: Square Pegs and Round Holes: SOIC Adapter
Post by: NivagSwerdna on August 01, 2020, 04:46:11 pm
I have recently bought some

[attachimg=1]

and I have an adapter based on OTS-28-1.27-04 ZIF Adapter like this... https://www.waveshare.com/ots-28-1.27-04.htm (https://www.waveshare.com/ots-28-1.27-04.htm)

(https://www.waveshare.com/img/devkit/Socket/OTS-28-1.27-04/SOP28_1.jpg)
Title: Re: Square Pegs and Round Holes: SOIC Adapter
Post by: NivagSwerdna on August 01, 2020, 04:50:46 pm
but... the IC is too wide to fit in the adapter (and too big for my PCB footprint) so something has gone wrong somewhere...

The datasheet https://www.cypress.com/file/43841/download (https://www.cypress.com/file/43841/download) describes the package as "28-pin SNC (300 Mils) SN28.3 (Narrow Body) Package Outline, 51-85092" with width (edge of pin to far side pin edge of 0.463/0.477 = 11.76/12.12mm)

I'm confused now because at the top of the datasheet it says... "Available in Pb-free and non Pb-free 28-pin (600-mil) PDIP, 28-pin (300-mil) narrow SOIC, 28-pin TSOP I, and 28-pin
reverse TSOP I packages" and I thought I had opted for "28-pin (300-mil) narrow SOIC"

But the IC doesn't fit in the adapter it is too wide!  What sort of adapter would I need for these?

I found this... https://www.cypress.com/file/117446/download (https://www.cypress.com/file/117446/download) which calls it SNC 28.300 rather than SOIC-28... but I don't find much when I google SNC... is it a non-standard footprint?  Is it basically too wide for all standard ZIF sockets??

Thanks in advance
Title: Re: Square Pegs and Round Holes: SOIC Adapter
Post by: OM222O on August 01, 2020, 08:18:52 pm
sounds like you have the 600 mil version (CY62256NLL-70PXC check the package marking), which is twice as wide. I'm not sure how much they cost, but easiest solution: order new chips with the correct footprint.

If you bought a huge reel and don't have production PCBs, then redesign the PCB. If you have bought a reel AND have the production PCBs, just put them aside, redesign the PCB so it fits both footprints, then use them for the later revisions which accommodate the larger footprint as well. this way no chips are unused.
Title: Re: Square Pegs and Round Holes: SOIC Adapter
Post by: NivagSwerdna on August 01, 2020, 09:00:56 pm
They are 300 mil body but very wide pins... must be a wide SOIC 28 version that I wasn't aware of... I have found some 11.9mm wide adapters... which is close.. (although they seem to be unobtainium...

https://www.waveshare.com/ots-28-1.27-23.htm (https://www.waveshare.com/ots-28-1.27-23.htm)