• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 21 subscribers
  • Views 136 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM5122: Configuration for 3-phase interleaved operation using LM5122

shibano satonori
Prodigy 20 points

Part Number: LM5122
Other Parts Discussed in Thread: UCC28950

Hello,
I am planning to use the LM5122 for a 3-phase interleaved boost converter with DC input.
While the LM5122 datasheet (Section 8.1.3) explains the dual-phase (2-phase) interleaved configuration using a Master-Slave setup, there are no specific examples or diagrams for a 3-phase configuration.
Could you please provide guidance or a reference design on how to achieve 3-phase interleaving? Specifically, I would like to know:
  1. Clock Synchronization: How should I connect the SYNCOUT and SYNCIN pins to achieve a 120-degree phase shift between the three phases?
  2. Master/Slave Setup: Is it possible to daisy-chain three devices, or is there a recommended way to distribute the clock?
  3. Feedback/Current Sharing: Are there any specific considerations for the COMP and FB pin connections to ensure balanced current sharing among the three phases?
My target operating conditions are as follows:
  • Input Voltage (VIN): [40-60] V
  • Output Voltage (VOUT): [200] V
  • Maximum Load Current: [70] A
Thank you for your support.
 
 

 

  • 0
    TI__Mastermind 35780 points

    Hello Miyano,

    Thanks for using the e2e forum.
    Unfortunately, the LM5122 device is only able to produce a 180deg phase shift by itself. A 120deg phase shift cannot be generated internally.
    For such a case, I would recommend to work with an external clock signal.

    I also noticed some problems with the target specs. Output voltage of 200V cannot be supported by the LM5122 device.
    The abs max rating of the SW pin is 105V. This limits the possible output voltage.

    I checked our webench tool for better suitable parts. The tool proposes a full bridge topology with UCC28950.
    You can consider opening a new e2e thread with this part number as topic to get forwarded to the according experts.

    Best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    Prodigy 20 points
    Hello Niklas
    I am currently looking for an alternative to the LM5122 for a non-isolated PFC circuit.
    The UCC28950 was suggested to me as a potential alternative. However, I understand that this device is primarily a Phase-Shifted Full-Bridge (PSFB) controller.
    Could you please confirm if the UCC28950 can be effectively used in a non-isolated PFC topology as a substitute for the LM5122?
    If this is a feasible solution, I would appreciate any guidance on the circuit configuration or any specific application notes you can provide. If there are better alternatives for a non-isolated PFC application, please let me know as well.
    Thank you for your support.
  • 0 in reply to shibano satonori
    TI__Mastermind 35780 points

    Thanks for the feedback.

    Unfortunately, I am not very familiar with the UCC28950d device, so I cannot say if the device can be used as non-isolated PFC or not. This is why I recommended to open a new thread.

    From my side, I can only say that the LM5122 cannot be used, as the SW abs max value is a limiting factor.
    There would be a workaround for the switch node by using a high side diode instead of a MOSFET, so the SW pin voltage is not required anymore, but working with diodes instead of a MOSFET for a 1,4kW system would lead to low efficiency with extreme losses, so I would not recommend this approach either.

    Best regards,
    Niklas