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Original question:

LM5143: The secondary LM5143's DITH pin connection in multiple phase application

LM5143: Synchronisation 4th channel out of synch

Thomas P.
Prodigy 50 points
Part Number: LM5143

Tool/software:

Hello  

We have installed two LM5143 in our design which generate different voltages in four channels.

In principle it works, runs at 800Khz target frequency and makes a stable PWM.

We connected these two ICs via the sync output and DEMB/SYNC input according to the data sheet.

However, with the second IC only one of the two switching regulators seems to synchronize correctly with the first switching regulator.

The last switching regulator channel also runs at 800Khz but asynchronously to the other one:

Can you please check this topic.

  • 0
    TI__Guru 73822 points

    Hi Thomas,

    SYNCOUT is 90° phase shifted, so the second controller should be at 90° and 270° wrt to channel 1 of the first controller. you can disable spread spectrum to correctly view the switching waveforms. Also, install the same RT resistance on both controllers. See app note SNVA870 in the product folder as a reference.

    Regards,

    Tim