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LT1054: Ripple performance of LT1054

Feng bin Su
Expert 8760 points
Part Number: LT1054
Other Parts Discussed in Thread: LM2776, , LM27761, TPS60403

Hi team,

My customer is using our LM2776 for their signal chain circuit but since there is a high ripple behavior at light load as below figure.

They have concern that it will influence the signal chain performance. So, they would like to consult with you whether LT1054 will have high ripple performance at light load, too.

  • 0
    Guru 317250 points

    The LM2776 reduces the switching frequency at light loads in order to safe power.

    To reduce the ripple, use a charge pump with a constant (and as high as possible) switching frequency, such as the TPS60403. The ripple can be further reduced with a LDO, such as in the LM27761.

    TI makes the LT1054 only for compatibility with the LT‍1054; why did the customer choose it?

  • 0 in reply to Clemens Ladisch
    TI__Guru* 78370 points

    Hi Feng,

    Thank you for reaching out.  Like Clemens said, the LM2776 has the PFM mode which skip cycles with resulted higher ripple voltage.  The LT1054 does not hat such PFM mode, and the ripple should be smaller.  

    Thanks,

    Youhao Xi, Applications Engineering

  • 0 in reply to Youhao Xi
    TI__Guru* 78370 points

    Hi Feng,

    Can I assume the issue is resolved and close the thread?  You are welcome to re-open it by adding a new post.

    Thanks,

    Youhao