Strange problem with a switching regulator

Thread Starter

Enrique Pérez

Joined Apr 26, 2017
4
Hello Folks

I am running out of ideas. I have designed a PCB with three Traco Power switching regulators: TSR1 2450. After an initial test with the three SW Regulators mounted, the PCB was broken because an overcurrent. Then I isolated one SW regulator in a Protoboard (see Pic1) and the SW regulator regulated the voltage rightly (Vin=10V, Vout=5V).

However when I mounted again the same regulator on the board (see Pic 2), the SW regulator did not work properly and I measured the output voltage and it was the same voltage (aprox.) like the input voltage (Vin=10V, Vout=9.6V). It is like the regulator short circuits the input with the output. Anyone has any idea about what can it be happening?.

Thanks in advance.
 

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AlbertHall

Joined Jun 4, 2014
12,345
Is there a short circuit between the input and output?
If there is, remove the regulator from the board and see if the short circuit is still on the board.
 

Thread Starter

Enrique Pérez

Joined Apr 26, 2017
4
I figure out that there is a problem with the impedance of the power planes:

Pic1 with the yellow board: Z(24V-GND) = 100K. Notice that there is not short circuit but the Impedance is very low...
Pic2 without the yellow board and the SW regulator mounted directly on the PCB: Z(24V-GND) = 200Ohm.

I guess that there is design failure anyway, but I would like to know if there is anyway to increase the plane impedance to solve this problem momentarily and go on with other tests...

thanks in advance.
 

Thread Starter

Enrique Pérez

Joined Apr 26, 2017
4
The SW regulator was mounted in the wrong way on the PCB and there was a mess because that....Begginer failure :-( Now it works perfectly :)

Greetings!!
 
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