PCB holes ?

[**DONOTDELETE**]

In my continuing self-defeating attempt to create my own circuit board with SMT, I'm needing to know what these hole symbols stand for:

A hole with crosshairs, a hole with a shaded center and a solid black hole.

All are shown on a two-sided PCB layout using a ground plane. (EDIT - as shown on the PCB layout for the Zetex 300 long battery life solution shown on page 9 of the ZXSC300 datasheet...end EDIT)

Is one a via? Are these standardized symbols, or does it depend on the PCB?

I've searched for answers without luck. I'll appreciate any help.

Mark

 

[**DONOTDELETE**]

It's a first! I've stumped the CPF.

Oh ... maybe something like this should become a weekly challenge ... hmmm ... let's see if that'll work.

This just became a contest. The first person to post here with the correct answer wins a brand-new, not before available, Zetex SX300 chip.

Mark

 

[Go Go Gadget Flashlight]

Mark, I believe they are simply graphic legends of hole size.

"th" means thousanths of an inch. Maybe?

 

[**DONOTDELETE**]

Gadget - thanks.

Okay, I admit to a serious case of the dumb fits! There's no other excuse for my missing the legend. Email me your address info and I'll stick the ZXSC300 in the mail (got a few direct from the manufacturer, the chip might just now be getting to distributors, but I doubt it).

I still can't figure out how to tell where the vias go (if any) nor what some of the holes are for that don't align with compenents. Any ideas?

Got the parts to build this and just don't want to waste time making the PCB only to end up with another dead board because I'm missing something so simply elemental as this that I'm ignorant about (lot of that going around lately).

Funny, after ordering all the parts for the ZX300 and 7 other DC-DC converters, they finally all come in the day after the LM2621 came! Being stubborn, I still want to build these circuits so the money & time isn't a total waste.

Mark

 

[Go Go Gadget Flashlight]

Mark, that's ok, really.

I don't think the ZTX chip would do me any good without all the other components anyway.

It is mainly geared toward a single white LED application, right?

You'll probably have to compare the schematic to the board layout to determine where vias need to be. You may even be better off to design your own board from the schematic.

Do you have any components gathered for a step-down SMD circuit? Maybe you could cut me a deal.

 

[**DONOTDELETE**]

Gadget:

Yes ... that layout is for a single LED. Wanted to build it up before doing my own PCB for the LS.

No ... sorry, all my chips/parts are for step-ups (except Linear 1308 SEPIC).

Yeah ... I figured I'd end up having to retrace the schematic to determine vias, etc. ... just being lazy I guess

. Their layout will work just fine with minor modification for the hanging tent light I'm after. I'll have to do my own for other applications.

FWIW, I cruised several of the chip manufacturer's step-down offerings last night and I couldn't find a better evaluation board than the LM3477 out there ... certainly from a price standpoint.

Natl Semi's evaluation board datasheet shows the PCB layout and it looks like you should be able to cut it down by about half in width and maybe 1/3 in height.

I think you got the last one, too. I wanted to order one, but they're "out of stock"!

Mark

 

[Go Go Gadget Flashlight]

I've talked to NatSemi.

My order was held up due to the out-of-stock issue. Supposedly, they get more today and will ship today. Check back with them if you are still interested.