maxim SMDs

Community PCB Design
1

Is it just me, or do Maxim SMD’s have weird dimensions?

2

Which ones, and what did you check them against? I’ve used a few of their SMD parts and didn’t notice anything strange about them.

Leon

3

leon_heller:
Which ones, and what did you check them against? I’ve used a few of their SMD parts and didn’t notice anything strange about them.

Leon

I’m working with a MAX6818. Most chips I’ve worked with are on a 150 or 300 mil grid, but this one is on either a 208 or 209 mil grid (different specs from different sources). I guess I have to wait until I have the part in hand and then break out the micrometer.

4

It’s metric; I’ve got the footprint in my Pulsonix library. I can give you the dimensions if you are stuck.

You should be able to find it on the IPC web site.

Leon

5

Specs are right in the datasheet and on Maxim’s site.

Package:

http://pdfserv.maxim-ic.com/package_dwgs/21-0056.PDF

Landing pattern:

http://pdfserv.maxim-ic.com/land_patterns/90-0094.PDF

0.65mm pin spacing does seem a little odd.

Who uses hardware debouncers anymore?

6

0.65 mm pin spacing is quite common, in fact.

That land pattern doesn’t look correct to me. The pad spacing should be 0.65 mm, the same as the package, not 0.66 mm. The pad sizes look wrong, as well. It says it conforms to IPC, but it’s quite different from the one I found with the PCB Matrix LP Viewer.

Leon

7

Really? I guess I just don’t notice the spacing much, since there’s usually already a pad layout I can steal from another part somewhere for these, but it seems to me the SSOP parts I use now are usually 0.5mm.

This should be a common package then. Usually, I would just find a package that looks the same and then to verify, print it out 1:1 and place the part on the paper to check if it’s okay.

8

TheDirty:
Specs are right in the datasheet and on Maxim’s site.

Who uses hardware debouncers anymore?

The project I’m working on requires some extremely time-sensitive code and I can’t spend precious milliseconds debouncing up to 16 inputs over and over again. I figured by using a hardware debouncer I can externalize all that nonsense and get on with what I need to do in the code, and I only have to read the inputs when there is a change.

leon_heller:
0.65 mm pin spacing is quite common, in fact.

Then I guess I better get used to it. Thanks for the feedback!