Sony SS-HQ1 Application Notes page 220

Internal phase comparison
The EXT-HD signal and the MCK-frequency-divided HD (MCK-HD) signal are phase-compared inside the
CXD3172AR, and the result of the comparison is output through PCOMP (pin 42). The PCOMP signal is
applied to the LPF (H-PLL) and fed back to the VCXO circuit on the MCK side to form the horizontal direction
PLL. The polarity of the PCOMP signal may be switched using PCMPINV (CAT7_Byte2_bit4).
An active or passive filter can be selected, to match the specifications of the external LPF. Note that we
recommend an active filter since active filters have better performance.
Fig 12.2-27 shows the PCOMP output waveform when the lock is on. Fig 12.2-28 shows the PCOMP output
waveform when the lock is off. (These waveforms are the results of measurements made using our evaluation
board.) Apply a trigger to EXT-HD and look at the PCOMP output waveform to check whether the lock is on.
Ch1
Ch2
Ch1:2.00V / DIV
Ch2:1.00V / DIV 20.0us / DIV
Ch1
Ch2
Ch1:2.00V / DIV
Ch2:1.00V / DIV 20.0us / DIV
[TRIGGER]
Fig 12.2-27 PCOMP output waveform (locked)
[TRIGGER]
PCOMP Waveforms Instability
Fig 12.2-28 PCOMP output waveform (unlocked)
EXT-HD
S1 input
PCOMP
output
214
- SS-HQ1 Application Notes -
Ver.1.0.0 January 7, 2005
EXT-HD
S1 input
PCOMP
output