I need to power a 55W 12v device that has a DC barrel jack

I have attached the specification of the PSU I intended to use however it has a 4 pin output of DC Output -Vo-Vo +Vo+Vo

Does this mean I would specifically need to use two 2pin JST connectors or can I use one 4 Pin JST?

 

If. you are just going to use one of the voltages available you only need two pins. There should be no problem in using a 4 pin connector for mechanical stability and strength and just leave the unused outputs not connected.

 

Depends on the size of the pins and the load you are supplying, but, yes. You are expecting about 2.5A out and 2.5A in - if the pins are tiny, then use all four terminals. If they are beefy, you can get a four-pin connector and populate only two of them to minimize components. Using a 2-pin connector can creat risk if the two pin connector is pushed into the wrong two supply pins (assuming your load may have a path to ground from some other downstream device (the risk is low but thought I'd mention it in case you have a more complex setup than you've described).

also, many barrel connectors are not built for 4+ amps so make sure you get an 5 amp or more barrel connector and 18-gauge wire. Some barrel connectors are for 0.5A and can get hot and even melt (the foil-thin solder lugs just don't like 4.5 amps).

 

Since the pins are rated for 10A maximum (with 18g wire), you can get by with just using 2 wires (2 wire connector) as long as your wire size can handle the 4A+ you plan to use.
Like others say, you can use a 4 pin shell, just don't wire the extra pins, and it will make the connector seat better, and prevent mistakes like plugging into the wrong 2 wires.

 

Thanks for the reply guys.

For simplicity, can I take a 4 pin JST connector and leave it as is(without disabling two of the ports) and just slot it straight over the 4 male pins on the PSU - IE all four pins will be delivering -Vo -Vo +Vo +Vo

I assume its much easier to find a 4 pin connector where all 4 pins are live, as opposed to modifying a 4 pin to make only 2 pins live and the other 2 just a plastic case.

 

Thanks for the reply guys.

For simplicity, can I take a 4 pin JST connector and leave it as is(without disabling two of the ports) and just slot it straight over the 4 male pins on the PSU - IE all four pins will be delivering -Vo -Vo +Vo +Vo

I assume its much easier to find a 4 pin connector where all 4 pins are live, as opposed to modifying a 4 pin to make only 2 pins live and the other 2 just a plastic case.

Yes, if you are buying a cable connector, yes, a 4 pin connector with four wires is fine. Check the price because some companies sell "2-populated" cable assemblies for some standard connector sizes - it might be cheaper.

If you are crimping pins onto wires and pushing the pins into the connector housing - then I would use only two.