NI PXI-5404
Phase-Locked Looping

The NI PXI-5404 has a PLL that optionally phase-locks the device clock to a Reference clock. With the NI PXI-5404, you can phase-lock to the PXI backplane clock, an external Reference clock that is brought in through the REF IN front panel connector, or a clock brought in from practically any other source. If you use an external clock, the nominal value of the frequency must be 10 MHz and the frequency must be within 100 ppm of 10 MHz. When phase-locking is disabled, the voltage from a DAC determines the frequency of the device clock. The value of this voltage provided by the DAC is established during factory calibration. The following figure shows the components and possible configurations of the phase-locking circuitry.