SNAU296 December 2023 LMK5C33414A
To use the DCO shift controls on a given APLL, enter the DCO ppb step value into the DCO Step Size (ppb) box shown below. The entered step size is used to calculate a numerator deviation and a 2 s complement numerator deviation. To perform the shift, the increment or decrement button must be pressed. An increment writes the numerator deviation to the DPLLx_FREE_RUN control, which results in a positive frequency shift in the amount specified by the DCO Step Size (ppb). An decrement writes the 2 s complement numerator deviation to the DPLLx_FREE_RUN control, which results in a negative frequency shift in the amount specified by the DCO Step Size (ppb).
The slew rate at which the adjustment occurs is set on the DPLLx_HOLD_SLEW_STEP control. Make sure the DPLLx_HOLD_SLEW_STEP is NOT equal to 0, otherwise the adjustment does not occur. The recommended DPLLx_HOLD_SLEW_STEP value is 63 (maximum value). A value of 63 results in the fastest adjustment.