• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 436 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.

Synchronizing multiple LM3150

Salah Zayouna
Intellectual 485 points
Other Parts Discussed in Thread: LM3150, LMZ31530, LMZ23610

Hi

I need to design four DC-DC converters of  5.5V/5A each. The requirement is to make them synchronized, the LM3150 is to be used specifically.

So I build the circuit, I shorted pin 7 together. The circuit is working fine but my concern is this is not confirmed ok in the datasheet. Is there any expected problem to connect pin 7 of the four ICs together? ..

The circuit is as from webench but also shorted pin 7 for the four ICs together.

Thanks

 

  • 0
    TI__Genius 16025 points

    Hi Salah,

    Synchronization means all 4 DC-DC converters would be in phase, switching at the same exact frequency. Since this controller uses the COT architecture, the On-times would be the same because the current, which is sensed based on the input voltage and fed back into RON, is the same but there is no guarantee on Off-times, which chiefly depends on the individual loads in your case. With different loads on each rail, the frequency of the individual regulators will be slightly different.

    As a result, you may notice waveforms which appear to be synchronized at any given common load but it is not true synchronization.

    Thanks,

    Anston

  • 0 in reply to Anston Lobo
    Intellectual 485 points

    Hi Anston,

    Thanks for answering. The four converters are giving exactly the same load, so I expect they all can be switched ON at the same time, but it is OK to have each one its own turn Off time .

    As you mentioned, I noticed it is not fully synchronized but it is better than free running (independently). 

    If to use one DC-DC converter, any suggestion for an interleave Buck converter, or (non interleave) can handle high current? Looking to design 400A/5V DC-DC converter. My current design is handling 60A/5V with some acceptable oscillation, but looking for more higher current.

     

  • 0 in reply to Salah Zayouna
    TI__Genius 16025 points

    HI Salah,

    There is no one DC-DC converter that can handle 5V/400A that I am aware of. You try using Webench power architect to find a solution comprising of multiple IC's and passives. 

    Or look up one of our power modules that can be paralleled together sucha s the LMZ23610 or LMZ31530.

    Thanks,

    Anston