LMX2571: Frequency Deviation Limitation in some Frequency

Hi there,

We know there is an overflow issue in LMX2571. We modify CHDIV1, CHDIV2, Multiplier and Prescaler to avoid the problem. But there are few frequency that we can not avoid. Is there any suggestion?

We use the internal VCO, and the setting is below,

Output Frequency: 87.2875 MHz

Reference Oscillator: 13 MHz (fixed in our design)

OSCin: 1

Multiplier: 1

R Counter: 1

DEN: 2^20

Prescaler: 4

CHDIV1: 7

CHDIV2: 8

The frequency deviation we want is 3.6 KHz.

The fraction part of N counter is 2016. The frequency step in FSK SPI FAST Mode to meet the 3.6KHz deviation is 4065. It will occur the overflow issue.

We do not want to use the frequency offset to solve this problem, because the receiver is using the same frequency. If we add frequency offset in the transmitter, the receiver will not receive the signal.

Thanks,

Ward