PLL calculation with FMzPLL or HalcoGen?

Burim Aliu

Intellectual 510 points

Other Parts Discussed in Thread: HALCOGEN

I am using the HalcoGen to configure the internal PLL of the TMS570 to 80 MHz

But with the same parameters the FMzPll Calculator gives as output 380 Mhz

Now my question is, which of them is correct?

Regards

Burim

PS: Halcogen version is 2.09 and FMzPLL calculator is v3.4

over 14 years ago

0 QJ Wang over 14 years ago

TI__Guru**** 200126 points

Hi Burim,

Both HALCoGen and FMzPLL are correct. If you check the PLL1 and PLL2 they generated, they should be the same. In HalCogen, the dividers and multiplier used in the diagram are the value written to the registers, but FMzPLL the real the divier and multiplier in the diagram. For example, writting 119 to PLL_MUL in HalCoGen diagram will generate f(VCO_CLK) = f(INT CLK)*(119+1). If you write 119 to FM2PLL diagram, 118 will be written to PLL1CTL register, and the f(VCO_CLK) = f(INT CLK)*(119).

Any question, please let us know.

Regards,

0 Burim Aliu over 14 years ago in reply to QJ Wang

Intellectual 510 points

Hi,

Thank you for the answer

Regards

Burim

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PLL calculation with FMzPLL or HalcoGen?