Hi Noel
I am looking at using the LMX2571 in an FM broadcast application, modulating frequency range will be 30Hz - 57KHz.
Will the 2571 support a modulating frequency of 57KHz providing the loop filter is wide enough? I guess it probably comes down to: will the 2571 support an I2S stream at a sample rate of 192k/16bit (at least 3.072MHz clock rate).
My next question, if the above is supported, is there any way to feed I2S directly into the I2S/FSK pins without having a microcontroller in between to do a conversion on the frame sync pulse? The reason I ask is because the timing diagram in datasheet for the I2S FSK input indicates that the frame sync pulse needs to coincide with the first bit clock, where at the Philips I2S specification indicates that this frame sync bit precedes the first bit clock.
One more question, the 2571 datasheet indicates that toggling the SPI pins while the PLL is in lock may degrade the phase noise, so I have decided not to use FSK FAST mode over SPI. Can you confirm if the same is true when toggling the FSK pins in I2S mode?
Thanks for your help
Gareth