LC78622NE
• Track jump modes
The table lists the relationships between acceleration pulses (the a period) , deceleration pulses (the b period), and
the braking period (the c period).
Standard track jump mode
b
New track jump mode
Command
a
c
a
b
c
1 TRACK JUMP IN (OUT) #1 233 µs
233 µs
60 ms
233 µs
233 µs
60 ms
60 ms
0.5 track
jump period
0.5 track
jump period
The same
time as “a”
1 TRACK JUMP IN (OUT) #2
1 TRACK JUMP IN (OUT) #3
233 µs
60 ms
0.5 track
jump period
This period does
not exist.
0.5 track
jump period
The same
time as “a”
This period does
not exist.
233 µs
233 µs
60 ms; TOFF is
low during
the C period.
60 ms; TOFF is
low during
the C period.
0.5 track
jump period
0.5 track
jump period
The same
time as “a”
1 TRACK JUMP IN (OUT) #4
1 track
jump period
The same
time as “a”
2 TRACK JUMP IN (OUT)
4 TRACK JUMP IN (OUT)
16 TRACK JUMP IN (OUT)
32 TRACK JUMP IN (OUT)
64 TRACK JUMP IN (OUT)
128 TRACK JUMP IN (OUT)
None
None
None
60 ms
60 ms
60 ms
60 ms
60 ms
60 ms
2 track
jump period
2 track
jump period
The same
time as “a”
466 µs
60 ms
60 ms
60 ms
60 ms
60 ms
9 track
jump period
7 track
jump period
9 track
jump period
The same
time as “a”
18 track
jump period
14 track
jump period
18 track
jump period
14 track
jump period
36 track
jump period
28 track
jump period
36 track
jump period
28 track
jump period
72 track
jump period
56 track
jump period
72 track
jump period
56 track
jump period
TOFF goes high during the period
when 256 tracks are passed over.
The a and b pulses are not output.
TOFF goes high during the period
when 256 tracks are passed over.
The a and b pulses are not output.
256 TRACK CHECK
60 ms
60ms
60 ms
60 ms
TRACK JUMP BRAKE
There are no a or b periods.
There are no a and b periods.
Note: 1. As indicated in the table, actuator signals are not output during the 256 TRACK CHECK function. This is a mode in which the TES signal is counted
in the tracking loop off state. Therefore, feed motor forwarding is required.
2. The servo command register is automatically reset after one cycle of the track jump sequence (a, b, c) completes.
3. If another track jump command is issued during a track jump operation, the content of that new command will be executed starting immediately.
4. The 1 TRACK JUMP #3 mode does not have a braking period (the C period). Since brake mode must be generated by an external circuit, care is
required when using this mode.
5. While there was no braking period (the C period) in the LC78620E/21E for the new track jump command “2 TRACK JUMP IN (OUT)”, this has been
changed in this LSI, which has a C period of 60 ms.
The THLD signal is generated by the LA9230M, LA9231M, or LA9240M, and the tracking signal is held during the JP pulse period.
No. 6015-15/31
SANYO [ SANYO SEMICON DEVICE ]
