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LM25122-Q1: LM25119 4 phase design

Jimmy wang
Prodigy 30 points
Part Number: LM25122-Q1
Other Parts Discussed in Thread: LM5122, LMC555

Hi Suppot members.

I have a 4-phase LM251122 application, which is Vin=25~33V, Vout=48.5V/22A. @235kHz, but still got some confusions.

1.when doing 4-phase operations, does it make any output difference(efficiency/power transient time....) between daisy chain and four individual clock(which is 90 deg shift)?

I agree that every channel Fsw will be different in these two solutions, and daisy chain's BOM cost might be lower than the induvidual clock. just would like to know if if there is another privilege I didnt see.

2. For the individual "clock", Can I have the most common/best solutions that been officially suggested for my setup.

I have seen the LM5122 applecations "Power Reference Design for 450W Automotive Audio Amplifier" which is using LMC555 &LM2936MP &CD3017BM96. Are they the best solution for me?

http://www.ti.com/product/LM5122/toolssoftware#TIDesigns    ==>from here

3. I haven't find a solution(IC) for 4 phase daisy chain clock. can anybody give me a official suggestion?

  • 0
    TI__Guru* 78270 points
    Hi Jimmy,

    Thank you for usign the LM25122. To answer your questions:

    1. You shouldn't see output difference because daisy chain just saves 2 clock signals but the 4phase interleaving operation either in daisy chain or using 4 individual clocks does not change. The daisy chain can simplify the design if the clock is generated from a microprocessor and the savings of two signals from the microprocessor become valuable because the number of GPIOs may be limited.

    2. the app note solution with LMC555 is a common way but not the only way. I would suggest to copy the clock to save time.

    3. Like illustrated in the datasheet, a simple D-Flip Flop should do the work. Note you still need an clock input to split it into two 180 degree shifted clocks. I suggest you to use the LMC555 as mentioned in 2.

    Thanks,
    Youhao Xi, Applications Engineering
  • 0 in reply to Youhao Xi
    Prodigy 30 points
    Soulds clear to me. Thanks Youhao