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UCC28070: Is there any way to sense each inductor current at FET source side using a sense resistor?

Kazuya Nakai59
Guru 21885 points
Part Number: UCC28070


 Hello guys,

 One of my customers is considering using UCC28070 for PFC portion of their new power supply module.

 Also they are going to use a SiC module for switching FET and rectifier diode. 

 But the internal FET drain is connected to anode of the rectifier diode internally.

 Therefore the current sense transformer can not be set between the FET drain side and anode side of the rectifier diode. 

 The customer question is the follow.

 Q. Is there any way to sense each inductor current using a sense resistor at FET source side?

 Could you please give me your reply? 

 Best regards,

 Kazuya.

  • 0
    TI__Genius 9140 points

    Hi Kazuya,

    it is possible to place the current sense resistor on the source side from controller.

    But you need to take specil care about the layout of the driving circuit of the sic mosfet . And avoid additional voltage from the current sense resistor to sic mosfet and FC controller GDA,GDB.

    also if only a current sense resistor  is added, the power loss should be high , make sure you can handle the power loss and accept the efficiency loss.

    if you use a current sense resistor+operational amplifier to increase the signal for the CSA and CSB, it should be better for efficiency.

    keep in mind make sure the current sense resistor sampling has the same scale as that used with current transformer.

  • 0 in reply to David Huang33
    Guru 21885 points

     Hi David,

     Thank you very much for your reply.

     I understood.

     Have you ever seen any reference circuit of FET source sensing?

     Or do you have any information for such current sensing way?

     Thank you again and best regards,

     Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Genius 9140 points

    Hello Kazuya,

    someone told me that TIDA-0130 use the current resistor+amplifier  solution, But I can find it on the TI website.

    you can refer to below captured of the sampling of current .

  • 0 in reply to David Huang33
    Guru 21885 points

     Hello David,

     Thank you very much for your reply.

     I see. Your reply is very helpful for the customer and me.

     I will ask them to use a module which FET drain is separated from anode of rectifier diode internally.

     Thank you again and best regards,

     Kazuya.