CXD3003 datasheet(82/137 Pages) SONY

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CXD3003R

• 2N-track jump

When $4C ($4D for REV) is received from the CPU, a FWD (REV) 2N-track jump is performed in

accordance with Fig. 4-11. The track jump count N is set with register 7. Although N can be set to 216

tracks, note that the setting is actually limited by the actuator. COUT is used for counting the number of

jumps when N is less than 16, and MIRR is used with N is 16 or more.

Although the 2N-track jump basically follows the same sequence as the 10-track jump, the one difference is

that after the tracking servo is turned on, the sled continues to move only for "D", set with register 6.

• Fine search

When $44 ($45 for REV) is received from the CPU, a FWD (REV) fine search (N-track jump) is performed

in accordance with Fig. 4-12. The differences from a 2N-track jump are that a higher precision is achieved

by controlling the traverse speed, and a longer distance jump achieved by controlling the sled. The track

jump count is set with register 7. N can be set to 216 tracks. After kicking the actuator and sled, the traverse

speed is controlled based on the overflow G. Set kick D and F with register 6 and overflow G with register 5.

Also, sled speed control during traverse can be turned off by causing COMP to fall. Set the number of

tracks during which COMP falls with register B. After N tracks have been counted through COUT, the brake

is applied to the actuator and sled. (This is performed by turning on the tracking servo for the actuator, and

by kicking the sled in the opposite direction during the time for kick D set with register 6.) Then, the tracking

and sled servos are turned on.

Set overflow G to the speed required to slow up just before the track jump terminates. (The speed should

be such that it will come on-track when the tracking servo turns on at the termination of the track jump.) For

example, set the target track count N –

α for the traverse monitor counter which is set with register B, and

COMP will be monitored. When the falling edge of this COMP is detected, overflow G can be reset.

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