188.8.131.52 SYSREF Procedure
To use SYSREF, do the these steps:
- Put the device in SYNC mode using the procedure already outlined.
- Figure out IncludedDivide the same way it is done for SYNC mode.
- Calculate the SYSREF_DIV_PRE value such that the interpolator frequency (fINTERPOLATOR) is in the range of 800 to 1500 MHz. fINTERPOLATOR = fVCO/IncludedDivide/SYSREF_DIV_PRE. Make this frequency a multiple of fOSC if possible.
- If using continuous mode (SYSREF_PULSE = 0), ensure the SysRefReq pin is high.
- If using pulse mode (SYSREF_PULSE = 1), set up the pulse count as desired. Pulses are created by toggling the SysRefReq pin.
- Adjust the delay between the RFoutA and RFoutB signal using the JESD_DACx_CTL fields.