cxa1372bs Sony Electronics, cxa1372bs Datasheet - Page 22

• Manufacturer Part Number: cxa1372bs
• Description: Rf Signal Processing Servo Amplifier For Cd Player
• Manufacturer: Sony Electronics

DIRC (Pin 20) and 1 Track Jump
Normally, an acceleration pulse is applied for a 1-track jump. Then a deceleration pulse is given for a specified
time observing the tracking error from the moment it passes point 0, and tracking servo is turned ON again.
For the 100-track jump to be explained in the next item, as long as the number of tracks is about 100 there is
no problem. However a 1-track jump must be performed here, which requires the above complicated
procedure. For the 1-track jump in CD players, both the acceleration and deceleration take about 300 to
400µs. When software is used to execute this operation, it turns out as shown in the flow chart of Fig. 9.
Actually, it takes some time to transfer data.
The DIRC (Direct Control) pin was provided in this IC to facilitate the 1-track jump operation. Conduct the
following process to perform 1-track jump using DIRC (normal High).
(a) Acceleration pulse is output. ($2C for REV or $28 for FWD).
(b) With TZC
(c) Set DIRC to High after a specific time.
inverted, deceleration is applied.
Both the tracking servo and sled servo are switched ON automatically.
As a result, the track jump turns out as shown in the flow chart of Fig. 10 and the two serial data transfers
can be omitted.
Fig. 9. 1-track jump not using DIRC (Pin 20)
$2C transfer latch
$25 transfer latch
$28 transfer only
Timer (0.3ms)
TZC
Latch
YES
(or TZC ), set DIRC to Low. (SENS Pin 27 outputs "TZC"). As the jump pulse polarity is
?
NO
Fig. 8. Pulse waveform and tracking error of 1-track jump
TR: REV
SL: OFF
TR: FWD
SL: OFF
TR: ON
SL: ON
Pulse waveform
Tracking error
Execute
Execute
Execute
– 22 –
Acceleration
Fig. 10. 1-track jump with DIRC (Pin 20)
Deceleration
$2C transfer latch
Timer (0.3ms)
DIRC = H
DIRC = L
TZC
YES
?
NO
TR: FWD
SL: OFF
TR: REV
SL: OFF
TR: ON
SL: ON
CXA1372BQ/BS
Execute