I'm working on a compact motor controller PCB that should control a 3-axis servo system with DC motors and magnetic absolute encoders. To mount the motors to the PCB, I'm looking for a connector with a small footprint, while still being able to handle the DC motor specs. The DC motors have a stall current of 1.6A, which will be limited by the motor driver IC to 1.2A max (25% below max, to prevent motor damage when stalling, as recommended by the vendor). The no-load current is 100mA.

My current considerations:

I do have a concern, as both connector systems are rated for 1A max per pin. In theory the motor should run at values well below 1A, and reach >1A for very short periods only when stalled, which should be prevented as much as possible (e.g. via software). Would it be a problem to use these connectors?


1 Answer 1


You should also take into consideration the wires you want to use. You can take this site as reference. There you can see from the column "Maximum amps for power transmission" that for 1.2A you should use at least AWG 21. The JST Connector is suited for AWG 28-32 wires, the Molex connector for AWG 26-32. Therefore I would say both connectors are not suited for your application.

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    \$\begingroup\$ Does that mean that I should always take into consideration the maximum rating, even though in common usage that rating should never be reached (because it can also damage the motor)? As the running current in normal use should be a few hunder mA. For the wires I plan on using 26AWG silicone wires that are rated for 3.5A, so hopefully this should be enough for the task. Thanks! \$\endgroup\$
    – Stathis
    Commented Jul 12, 2022 at 10:10
  • \$\begingroup\$ Well yes you have to take into consideration the maximum rating of your components. If you are sure those maximum ratings are not exceeded for a long period of time, you can use them. I personally would always make sure to have some margin for error. With the cables rated for 3.5A you should be on the safe side though ;) \$\endgroup\$
    – l.voe
    Commented Jul 12, 2022 at 14:38

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