WEBENCH® Tools/LMK03328: LMK03328RHSR

Kerry Tracey

Part Number: LMK03328

Tool/software: WEBENCH® Design Tools

I am using a LMK03328 with 10.949297MHz going into PRIREF+/- inputs. I need to output 10.4926MHz. When I run WEBENCH I get PLL Whole Part = 0, PLL Numerator = 1, and PLL Denominator = 2.0. When I enter this into TICS Pro I don't get 10.4926MHz out. FYI, VCO freq = 10.949MHz. Can I get actually get 10.4926MHz out? If so could you tell me exactly what my setting should be.

over 4 years ago

0 Vibhu Vanjari over 4 years ago

TI__Genius 11900 points

Hello Kerry,

The VCO frequency cannot be 10.949 MHz. The VCO frequency must be between 4.8-5.4 GHz.

You can pass your PRIREF/SECREF frequency through to OUT 4,5,6 or 7. You can refer to the datasheet (10.6 Register Maps) for detailed register settings or use our TICS Pro software to configure the device easily: http://www.ti.com/tool/ticspro-sw.

Here's an example, you can set OUT_5 to output PRIREF by setting R39[7:6] to 0x2.

0 Kerry Tracey over 4 years ago in reply to Vibhu Vanjari

Intellectual 450 points

I understand that the VCO frequency can not be 10.949MHz, however that's what the WEBENCH show. I not sure how I'm supposed to know what it should be or how I can determine what it should be.

LMK03328 10.949MHz webench_design PLL1.pdf

0 Vibhu Vanjari over 4 years ago in reply to Kerry Tracey

TI__Genius 11900 points

Hello Kerry,

"I understand that the VCO frequency can not be 10.949MHz, however that's what the WEBENCH show."

If you look at the block diagram on the first page of the pdf you attaced. It shows the VCO frequencies to be ~4905.28 MHz and ~4805.61 MHz.

You can obtain the required 10.4926 MHz, by dividing down (divide by 458) from the ~4805.61 MHz VCO. Please use this VCO frequency.

I suspect that there is some typo-error in generating the pdf as it later suggests the input frequency as the VCO frequency.

0 Kerry Tracey over 4 years ago in reply to Kerry Tracey

Intellectual 450 points

I think I figured it out.

N Divider fraction = 143645/250445, N Divider = 573559064865. VCO will then equal 5246.3241030964982. Out Divier 1 = 2 giving PLL2_OUT = 2623.16205154825. I then set Output Dividers to 250.

Clock & timing

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WEBENCH® Tools/LMK03328: LMK03328RHSR