Figure 5. Synchronized Reference Signal Characteristics - Seagate Elite 9 Product Manual

Elite 9 Product Manual, Rev. C
Rotational position locking
Note. Mode Select page 04h, byte 17, bits 0 and 1.
RPL Description
00b Spindle synchronization is disabled (default value)
01b The target operates as a synchronized-spindle slave
10b The target operates as a synchronized-spindle master
11b The target operates as a synchronized-spindle master control
(not supported by the disc drive)
The VIC 2 LSI on the master drive provides the reference signal (SSREF+).
The index signal generates a 90 Hz signal. The signal is normally
false/negated (nominal 0V) and makes a transition to the true/asserted
(nominal +5V) level to indicate the reference position during the revolution
period. Master and slave drives use the trailing (falling) edge of the
reference signal to phase-lock their spindles. A maximum of 10 seconds
is allowed for a slave to synchronize with the reference signal. Figure 5
shows the characteristics of the reference signal.
1
SSREF +
0
T = 0.0083 seconds (± 1.0% max)
± 10 microseconds cycle-to-cycle variance
± 20 microseconds phase error while synchronized

Figure 5. Synchronized reference signal characteristics

T
1.0 microsecond min.
1.37 microseconds max.
17