USB (48 MHz) connector - can I use a plastic housing?


#1

Hi,

I am designing a product that needs a USB connection to a PC.

The case is made from ABS and has some connectors already decided, they are plastic quick connect types like this, in different colours and pin counts.

I just have the USB connector to go.

I can either go for this type:

which is obviously a standard USB mini connector.
Pro’s:

  1. standard USB connector means a standard USB cable can be used
  2. includes shielding against EMI

Cons:

  1. Milling the enclosure requires high precision and the PCB must be slid sideways during assembly
    OR
  2. The connector needs to be fitted onto a tiny PCB and connected to the main PCB using a cable (FFC with ground between each wire)

Alternatively I can use something like a 4-pin connector Redel like the first picture

Pro’s:

  1. Same look as the other connectors (but different colour and pin count)
  2. Easy to mill hole in the enclosure
  3. The other connectors will use a connector board, which can then be shared if designed well

Cons:

  1. Not shielded
  2. Requires a custom cable at one end (but very simple to make, solder 4 wires…this is not a volume product, and other cables need to made anyway)

What I would like to ask the community here is this: what kind of connector can be used for a 48 MHz USB signal while observing electromagnetic compatibility regulations? Does it have to be USB with shielding, or can it be an industrial 4-pin connector? If the enclosure is plastic - does it matter if the connector is metal or plastic as a metal housing won’t be electrically connected anyway?

Thanks for any insights!


#2

Bulgin PX0443 paired with Bulgin 14192, and Bob’s your uncle.


#3

Hi, Joseph,

Thanks for the reply!

It’s a good suggestion, but unfortunately there are some issues with it. Firstly the connector is too large. I have tried it, and I had to cut the PX0443 down top and bottom in order to fit into the case. Second the mating cable only comes in 2 meters, which is really long for my need. It’s impossible to source a good looking and reliable type A connectors. Only over-moulded connectors work properly and look good. And the PX0443 is just too ugly to use with a regular mini USB cable…

I did try another alternative USB connector from Amphenol. The connector fit, but they don’t even supply the type A connector on their cable…

I think I have found an acceptable solution, though:

Still, I’d love to hear from someone if 48MHz USB can be transferred through an unshielded, plastic connector :smile: