Position of mounts and pinouts - 20W Adjustable DC-DC Buck Converter with Digital Display

Support Product Questions
1

Hi, I’m designing a PCB board and will be mounting some of these buck converters on it that I have purchased from your store.
I was just wondering if you would be able to give measurements for the board dimension, pin-holes, mounting holes and the holes the screw terminals are in that are reasonably accurate as I don’t trust measuring it with the image and ruler markings provided haha, sorry.

Thanks in advance!

2

Hi Cameron,

Welcome to the forum :slight_smile:

I’ve taken some measurements of a module we have in stock using some Vernier callipers which should get you a fairly close rundown of the dimensions.

The board I have is 65mm long by 38.9mm wide. Since these are manufactured as panels which are broken down into individual PCBs there is some roughness on the lower edge where the module is separated from its neighbour, so it’s probably safe to expect around +/- 1mm of tolerance there.
The height off the desk to the tallest point is 16mm (the top of the trimming potentiometer adjustment).

The mounting holes are just a touch larger than 3.5mm diameter and centred about the same distance off the edge of the PCB.

The terminal blocks are positioned in the centre of the PCB and are themselves 10.5mm wide with a pin pitch of 4.7mm (distance between the centre of each pin in the terminal block).

It seems the current version of this module we’ve received is slightly different in shape and size from the last revision we received from our supplier. So I’ll get those photos updated on the website and update the dimensions in our description shortly.

dc-dc converter dimensions
dc-dc converter dimensions1141×742 189 KB

3

Hi Trent

Are you sure about that?? In my experience this style of terminal block has a pin pitch of 0.2" or 5.08mm. The overall length being the number of pitches + 1 X pin pitch (which would actually be the number of terminals X pin pitch) which in this case would be 10.16mm.

Or have the powers that be snuck another “standard” on us.
Cheers Bob
PS. You did zero the callipers first didn’t you. I know mine needs a bit of a clean occasionally or it can tell fibs at times.

4

Hey Bob,

I spoke to Trent about this and he agrees it is super strange, the measurement was done by measuring the 2 pins on the underside of the board (assuming they would be central to each hole in the terminal block). So its possible that it may not be dead on, but in order to minimise the math (and capability for human error) he went with that route instead.

I can assure you Trent’s an absolute legend with his Vernier’s, it just seems this product may be that special outlier that is trying to set a new trend.

Cheers,
Blayden

5

Hi Blayden, Trent
To save any errors trying to find the centre of the pins I usually measure to the outside of 2 adjacent pins then subtract the diameter of one of them.

You can usually lock pairs of this type together so the overall width HAS to be a multiple of the pitch. Trent’s measurement certainly does not meet this criteria. But if they are not the lockable type this could be anything except in a case where you did mount them side by side then a multiple of the pitch would be minimum or the holes would not fit on any recognised grid.
Cheers Bob

6

Hi Bob,

Thanks for keeping me honest, having looked at the square front face of the terminal block originally I thought it would be pointless trying to properly measure the centre of a not quite square hole and figured the through hole pin spacing, measured centre to centre would be very close to the pin pitch anyway.
I just grabbed another unit to remeasure and saw that on this unit one through hole pin has been bent over, likely causing the reason for the error in my measurement yesterday.

2023-09-15_16-57-39_IMG_2703
2023-09-15_16-57-39_IMG_27031920×2560 103 KB

I’ve remeasured a unit using your proposed method and the round(ish) holes in the top of the terminal.
The distance from the two outer edges is 8.5mm and the diameter of one hole was 3.47mm

By your method I calculated 5.03mm pin pitch, likely within measurement error of the 5.08mm you said was a standard.

image
image587×786 41.2 KB

7

Hi Trent

Fits the “standard” universal 0.1" grid.
0.1" = 2.54mm X 2 = 5.08mm X 2 = 10.16mm which should be the overall length of the terminal block.

I believe the 0.1" and multiples / sub multiples is still a universal standard grid although connector manufacturers seem to have dreamed up a lot more I think in the ongoing quest for ultimate miniaturisation.
Cheers Bob