![](http://datasheet.mmic.net.cn/40000/LC78631E_datasheet_1644978/LC78631E_14.png)
No. 5342-14/34
LC78631E
TJ commands
When the LC78631E receives a track jump instruction as a servo command, it first generates accelerating pulses
(period a) and next generates deceleration pulses (period b). The passage of the braking period (period c) completes
the specified jump. During the braking period, the LC78631E detects the beam slip direction from the TES and
HFL inputs. TOFF is used to cut the components in the TES signal that aggravate slip. The jump destination track
is captured by increasing the servo gain with TGL. In THLD period TOFF output mode the TOFF signal is held
high during the period when THLD is high.
Note: Of the modes related to disk motor control, the TOFF pin only goes low in CLV mode, and will be high
during start, stop, and brake operations. Note that the TOFF pin can be turned on and off independently by
microprocessor issued commands. However, this function is only valid when disk motor control is in CLV
mode.
Code
Command
RES = low
$A0
OLD TRACK JUMP
q
$A1
NEW TRACK JUMP
$11
1 TRACK JUMP IN #1
$12
1 TRACK JUMP IN #2
$31
1 TRACK JUMP IN #3
$52
1 TRACK JUMP IN #4
$10
2 TRACK JUMP IN
$13
4 TRACK JUMP IN
$14
16 TRACK JUMP IN
$30
32 TRACK JUMP IN
$15
64 TRACK JUMP IN
$17
128 TRACK JUMP IN
$19
1 TRACK JUMP OUT #1
$1A
1 TRACK JUMP OUT #2
$39
1 TRACK JUMP OUT #3
$5A
1 TRACK JUMP OUT #4
$18
2 TRACK JUMP OUT
$1B
4 TRACK JUMP OUT
$1C
16 TRACK JUMP OUT
$38
32 TRACK JUMP OUT
$1D
64 TRACK JUMP OUT
$1F
128 TRACK JUMP OUT
$16
256 TRACK CHECK
$0F
TOFF
$8F
TON
q
$8C
TRACK JUMP BRAKE
$21
THLD PERIOD TOFF OUTPUT MODE
$20
RESET THLD PERIOD TOFF OUTPUT MODE
q