LMX2571: DEN-register value

May

Part Number: LMX2571

Hi,

Customer is using LMX2571 and they want to generate a carrier with 12.5 kHz channel spacing, that is 2-FSK modulated.

According to them, they have read on page 26 datasheet, in table 14, R24 Register Field descriptions for Bit 10, that the DEN should be zero.

But the combination of DEN and NUM are the power of the fractional N PLL. Is this requirement, that DEN = zero only for the moment, where the FSK_EN_F2 is set, valid? Or can you be more precise what is meant here? Because in the chapter 8.1.1, the DEN value is clearly an important part of the FSK modulation.

Thank you in advance.

Regards,
Maynard

over 4 years ago

0 Noel Fung over 4 years ago

TI__Guru** 114760 points

Hi Maynard,

Right, DEN=0 is required only when FSK is active. So you can use different DEN for the same frequency channel, DEN=0 during FSK and DEN=other value when there is no modulation.

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LMX2571: DEN-register value