Info!! Reducing Vibrations On Opened Upwards Frame Ability Supplies

We larn a lot of questions on how to cut noise, both output & EMI (ElectroMagnetic Interference), on opened upwards frame ability supplies.  Usually it is a final result of a failure to soil the production correctly.  With an enclosed ability supply, encased inwards a metallic box, it is uncomplicated every bit all the connections are made for the user past times the chassis.  Connect upwards the input in addition to output wiring in addition to everything plant fine.  With an opened upwards frame (pcb type) it is a piddling different.

TDK-Lambda’s ZPSA opened upwards frame ability supply

First a expect at what nosotros are aiming to do.  Below is a simplified diagram of the racket decoupling capacitors inwards a typical ability supply.  The Y capacitors on the left provide a depression impedance path for high frequency racket to ground.  This avoids electrical racket (EMI) exiting the ability provide in addition to interfering amongst other devices on the air-conditioning input.   The capacitors on the right accept the same function, but inwards this example stops electrical racket from appearing on the output of the ability provide in addition to interfering amongst the load.  In some cases, simply 1 capacitor is sufficient.

You tin sack consider 2 blueish Y capacitors on the ZPSA photograph, roughly 1 of the mounting holes.

Looking at the underside of the ZPSA pcb, nosotros tin sack consider the locations of those capacitors.

The cherry arrow shows the Y capacitors CY2 in addition to CY3 are connected to a mutual draw that leads to the bottom left mounting hole.  This hole is inwards fact a plated through hole in addition to the mounting screw in addition to standoff volition brand a connexion amongst that trace.
The blueish arrow shows the output to soil capacitor CY1, 1 time to a greater extent than connected to a copper draw leading to the bottom right mounting hole.

Note that inwards the example of the ZPSA, at that topographic point is no pcb draw betwixt those 2 holes.  (The spill out 2 mounting holes produce non accept whatsoever traces going to them, then nosotros tin sack ignore them electrically.)

Looking at our schematic again, nosotros ask a connexion from chassis soil to both the input in addition to output capacitor traces to cut the electrical noise.  This nosotros produce past times mounting the ability provide on a grounded metallic plate, amongst metallic standoffs in addition to screws.

Follow these guidelines in addition to the opened upwards frame ability provide volition come across the EMI in addition to output racket specifications.

Power Guy