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LM5146-Q1: Datasheet clarification

Gerald
Genius 9575 points
Part Number: LM5146-Q1

Hi Team,

May I ask for help? my customer found a mistake in datasheet and I would like to ask if you can also check this in your side?

Below is our customer statement/comment:

"I guess there is a mistake in the Table 9-2 in SNVSB32B.
According to equation 82 in SLUP340 the first pole of compensator network is defined by RFF (RC2 in SNVSB32B) and CFF (CC3 in SNVB32B). But in SNVB32B first pole is defined by RC1 and CC2.
According to equation 83 in SLUP340 the second pole of the compensator network is defined by RCOMP (RC1 in SNVSB32B) and CHF (CC2 in SNVSB32B). But in SNVB32B first pole is defined by RC2 and CC3.
Table 9-4 in SNVSB32B also includes wrong equations for calculating CC2 and RC2.
Excell Calculator for this chip calculates this components correctly by the way."

We will be thankful for your response.

Kind regards,

Gerald 

  • 0
    TI__Guru 57555 points

    Hello

    Thank you for bringing this to our attention.

    We will investigate this issue.

    The calculator tool is your best resource for designing this regulator.

    Thanks

  • 0
    TI__Mastermind 49317 points

    Hi Gerald,

    Table 9-2 looks correct. There are two poles - one set by Rc1 and Cc2 that typically goes at Fsw/2, the other set by Rc2 and Cc3 that cancels the Cout ESR zero.. The expressions match what's indicated in the figure attached to Table 9-2 as follows (click on the image for a high res version):

    Table 9-4 also aligns with this.

    The error is actually in the text preceding Table 9-4. It should be: ωp1 = ωsw/2 and ωp2 = ωESR. I will fix this in the next update cycle.

    Regards,

    Tim