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LM5157EVM-FLY: The hiccup mode of LM5157

Rannie Zhou
Intellectual 1160 points
Part Number: LM5157EVM-FLY

Hi,

In the guidebook, the waveform of hiccup mode is shown. In the hiccup mode, 64 cycles current limits are detected, the switching is stopped and restart after 32768 cycles. As the frequency is 250kHz, this time of detection should be 0.265ms. But in the guidebook, the time that I(o1) is at high level seems too large.

I also test the EVM. The waveform is shown as follow. The time of HICCUP is larger than the results in guidebook. 

  • 0
    TI__Genius 16180 points

    Hi Rannie,

    Thanks for reaching out to us via e2e.

    It is a bank holiday today. Please expect a response by Wednesday.

    Best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    TI__Genius 16180 points

    Hi Rannie,

    Sorry for the delay.
    According to the datasheet, only the cycles that actually reach the current limit are counted towards to 64 cycles until hiccup mode.
    Can you check if the current limit is reached with every cycle during the operation time?

    The first waveform you sent is rather small, so I cannot see the sensed current signal values in detail.

    Thanks and best regards,
    Niklas