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  • TI Thinks Resolved

LMX2572: Partial Assist Question

Prodigy 140 points

Replies: 1

Views: 78

Part Number: LMX2572

Hello - 

We've been successfully using this part for almost 2 years now.  I am now interested in trying to speed up the calibration time.  So I thought I'd give "Partial Assist" a try (section 8.1.4.1 in the datasheet).  I have found experimentally that writing VCO_SEL r20[13:11] causes the rb_VCO_SEL r110[7:5] to be incorrect.  Aka, I can only verify my partial assist settings if I don't write VCO_SEL.  Is that expected?  Is there some other write that's needed to make rb_VCO_SEL accurate assuming Partial Assist?

Without writing VCO_SEL, it looks like my calculations (table 135 plus eq5 and eq6) are pretty close to the "rb" values.  So I'm not worried about the table or the calculations.  

Thanks

Chris H

  • Hi Chris,

    What is the VCO_SEL you have assigned and the read back VCO_SEL value? Is the desired VCO frequency located in the boundaries of two adjacent VCO core?

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