cxd2548r Sony Electronics, cxd2548r Datasheet - Page 86

• Manufacturer Part Number: cxd2548r
• Description: Cd Digital Signal Processor With Built-in Digital Servo And Dac
• Manufacturer: Sony Electronics

§4-12. Brake Circuit
Immediately after a long distance track jump it tends to be hard for the actuator to settle and for the servo to
turn on.
The brake circuit prevents these phenomenon.
In principle, this circuit cuts unnecessary portions of the tracking drive and applies the brake by utilizing the
180° offset in the RF envelope and tracking error phase relationship which occurs when the actuator traverses
the track in the radial direction from the inner track to the outer track and vice versa. (See Figs. 4-10 and 4-11.)
Concretely, this operation is achieved by masking the tracking drive using the TRKCNCL signal generated by
loading the MIRR signal at the edge of the TZC (Tracking Zero Cross) signal.
The brake circuit can be turned on and off by D18 of $1. (See Fig. 4-5.)
TRKCNCL
Register name Command D23 to D20 D19 to D16
SENS
TZC out
RF
Trace
MIRR
TZC
Edge
TRK
DRV
TRK
DRV
TE
1
0
0
TRACKING
CONTROL
FWD
JMP
REV
JMP
Fig. 4-10.
Inner track
Servo ON
0 0 0 1
Outer track
1 0
0
1
0
0
1
Fig. 4-5.
1
0
– 86 –
TRKCNCL
ANTI SHOCK ON
ANTI SHOCK OFF
BRAKE ON
BRAKE OFF
TRACKING GAIN NORMAL
TRACKING GAIN UP
TRACKING GAIN UP FILTER SELECT 1
TRACKING GAIN UP FILTER SELECT 2
SENS
TZC out
RF
Trace
MIRR
TZC
Edge
TRK
DRV
TRK
DRV
TE
0
0
REV
JMP
FWD
JMP
Fig. 4-11.
Outer track
Servo ON
Inner track
: Don't care
CXD2548R