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LM5143A-Q1: Problem with the sensing current (DCR method)

SAGARA Issa
Prodigy 20 points
Part Number: LM5143A-Q1
Other Parts Discussed in Thread: LM5143

LM5143-Q1 BCS15 et BSC15 (1).xlsm

we want operate in interleaved 2 phase for (12V input) and (100A, 5V in output). if we operate with only one channel we can obtain 55A in output but if we connect the both channels we can obtain basically 45A. I join the scope screenshot for one channel.

 

  • 0
    TI__Mastermind 22301 points

    Sagara,

    Thank you for your quickstart calculator.

    Looking at your Vcs1 waveform it looks like SW2 from the other phases is coupling onto current sense waveform.

    This is likely causing noise coupling and early current limiting.

    DCR current sensing should use current sense capacitance close to pins, this should help filter differential mode noise if selected correctly. 

    You can also try using a common mode capacitor (just VOUT to GND) close to current sense VOUT pin to reduce noise.

    Note the current sense VOUT should be separate trace from VOUT to FB trace. Current sense VOUT trace needs to be closely coupled to CS trace.

    Using the same VOUT trace for CS and FB will cause more current sense noise to be coupled from FB branch.

    Hope this helps,

    -Orlando