No. 6329-16/40

LC78628E

Code

Command

RES = low

$A0

Previous Track Jump Mode

q

q

$A1

New Track Jump Mode

$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

q

$8C

TRACK JUMP BRAKE

$21

JP pulse period TOFF output mode

$20

Reset the JP pulse period TOFF output mode

q

q

• Track jump commands

c

b

a

JP–(+)

JP+(–)

(Braking period)

(JP pulse width)

TGL

A12812

When the LC78628E 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 LC78628E 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 JP pulse period TOFF output mode, TOFF goes high during the period that JP pulses are

generated.

Note: Of the modes related to disc motor control, the TOFF pin goes low only 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 valid only when disc motor control is in CLV mode.