ZHCSGL5C March 2017 – April 2019 LMX2594
PRODUCTION DATA.
The LMX2594 can generate a SYSREF output signal that is synchronized to fOUT with a programmable delay. This output can be a single pulse, series of pulses, or a continuous stream of pulses. To use the SYSREF capability, the PLL must first be placed in SYNC mode with VCO_PHASE_SYNC = 1.
As Figure 30 shows, the SYSREF feature uses IncludedDivide and SYSREF_DIV_PRE divider to generate fINTERPOLATOR. This frequency is used for reclocking of the rising and falling edges at the SysRefReq pin. In master mode, the fINTERPOLATOR is further divided by 2 × SYSREF_DIV to generate finite series or continuous stream of pulses.
The delay can be programmed using the JESD_DAC1_CTRL, JESD_DAC2_CTRL, JESD_DAC3_CTRL, and JESD_DAC4_CTRL words. By concatenating these words into a larger word called "SYSREFPHASESHIFT", the relative delay can be found. The sum of these words should always be 63.
SYSREFPHASESHIFT | DELAY | JESD_DAC1 | JESD_DAC2 | JESD_DAC3 | JESD_DAC4 |
---|---|---|---|---|---|
0 | Minimum | 36 | 27 | 0 | 0 |
... | 0 | 0 | |||
36 | 0 | 63 | 0 | 0 | |
37 | 62 | 1 | 0 | 0 | |
... | |||||
99 | 0 | 0 | 63 | 0 | |
100 | 0 | 0 | 62 | 1 | |
... | |||||
161 | 0 | 0 | 1 | 62 | |
162 | 0 | 0 | 0 | 63 | |
163 | 1 | 0 | 0 | 62 | |
225 | 63 | 0 | 0 | 0 | |
226 | 62 | 1 | 0 | 0 | |
247 | Maximum | 41 | 22 | 0 | 0 |
> 247 | Invalid | Invalid | Invalid | Invalid | Invalid |