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UCD3138: Questions of UCD3138 and phase shift full bridge topology

Steven Rogers86
Intellectual 350 points
Part Number: UCD3138

Hi,

Below is C2000 PSFB SR behavior,there are three sr modes working on firmware ,so my question is does UCD3138 can implement this SR behavior like C2000?

Does it have any risk when sr mode was switching?

For sr mode 1 & 2 ,why sr mode 1 is more suitable that working on very low load than sr mode 2?thanks.

  • 0
    TI__Genius 17090 points
    Yes, the UCD3138 supports the same three modes. You do need to switch between them with software control. If you look at the UCD3138 Technical Reference Manual, Section 6.9, you will see the description of IDE support. Note that we generally don't use the DCM detection hardware. We prefer to use load based firmware switching between IDE and full width SR. You can do this by changing the IDE_EN. To disable the SR altogether, Just disable those pins somehow.

    We have a little bit of IDE in our HSFB EVM. It's not enabled, I don't know if it is complete. We don't have it in our PSFB because it doesn't work with Peak Current mode. It only works in voltage mode, because it uses the pulse width on the primary FET to calculate the ideal diode timing on the SR. As you will see in the documentation, software needs to calculate a coefficient based on Vin and Vout and feed that to the hardware.