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UCC21520: Relay to connect and disconnect transformers at the switch node of SMPS

Bright Robert
Intellectual 340 points
Part Number: UCC21520


Tool/software:

Hi,

I want to ask question regarding using relay (G5Q-1A4-DC12) at the switch node of half bridge circuit to connect and disconnect individual transformers contacted in parallel to the circuit. See the attached image below. The transformers are connected via relay to the floating side and in between the two capacitors that form a half bridge circuit as shown in the attached image. The relay is just to turn ON/OFF the transformer that is not required during operation. The switching frequency of the gate driver circuit is 25kHz to 39kHz. 

1) Is the relay appropriate in the switch node?

2) Is there any better approach of achieving this requirement?

Half Bridge circuit v1.pdf

Kind regards,

Bright

  • 0
    TI__Genius 9056 points

    Hi Bright,

    I cannot comment on the relays since I have not seen an application of relays in half bridges but it seems like it should not be an issue unless it is causing issues with the gate driver. 

    If you have any problems with the gate driver in this application, feel free to ask!

    Regards,

    Hiroki

  • 0 in reply to Hiroki Honda
    Intellectual 340 points

    Hi Hiroki,

    Thank you for your reply. 

    I found the answer. I can use it to switch the transformers ON/OFF but the relay  must be turned either ON/OFF before the turning on the switching circuit and must be rated to the correct AC voltage. 

    Kind regards,

    Bright