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UCC24612: UCC24612 does not work properly

Other Parts Discussed in Thread: UCC24612

We design and develop a 100KHz drive flyback converter power supply with 100V AC 50/60Hz input and 12V 6A output.

 

In order to configure the secondary-side synchronous rectification, the circuit was configured according to the application circuit example of UCC24612 using UCC24612. However, the FET drive signal of synchronous rectification is terminated in an instant, and synchronous rectification does not operate according to the specifications. Removing noise from the rectifier voltage signal with a CR filter improves the situation slightly, but the FET gate drive signal is only emitted for a short period of time.

The rectifier circuit on the negative side is configured, but it does not operate according to the specifications.

I am designing in Japan, is it possible to get support?

  • Hello,

    I am reviewing your inquiry and will get back to you shortly.

    Regards,

  • Hello,

    For the FET to stay on the Ids*Rdson of your FET needs to be greater than 10 mV.  At full load the Ids*rdson > 50 mV to drive the FET at its maximum.

    First, I would check your design to make sure that the Rdson*Ids not too low.

    Second, If it is not too low noise on the Vds could be causing the gate driver to turn-off.  You should be able to remove this by adding a snubber across the drain to source of the FET. 

    Third, having a good layout is key.  There is layout guidance and example in the data sheet.  There is also a UCC24612 EVM that has a proven layout which you can copy.  You can find it at the following link.

    https://www.ti.com/lit/pdf/sluubp3

    Regards,