Philips SAA7345

1998 Feb 16 23

Philips Semiconductors Product speciﬁcation

CMOS digital decoding IC with RAM for

Compact Disc SAA7345

OPERATION MODES

The motor servo has the operation modes as shown in Table 9 and is controlled by the motor mode register

(address 0001).

Table 9 Operation modes.

MODE DESCRIPTION

Start mode 1 Disc is accelerated by applying a positive voltage to the spindle motor. No decisions are involved

and the PLL is reset. No disc speed information is available for the microcontroller.

Start mode 2 The disc is accelerated as in Start mode 1, however the PLL will monitor the disc speed. When the

disc reaches 75% of its nominal speed, the controller will switch to Jump mode. The motor status

signals are valid (register 0010).

Jump mode Motor servo enabled but FIFO kept reset at 50%. The audio is muted but it is possible to read the

subcode.

Jump mode 1 Similar to Jump mode but motor integrator is kept at zero. Used for long jumps.

Play mode FIFO released after resetting to 50%. Audio mute released.

Stop mode 1 Disc is braked by applying a negative voltage to the motor. No decisions are involved.

Stop mode 2 The disc is braked as in Stop mode 1, but the PLL will monitor the disc speed. As soon as the disc

reaches 12% of its nominal speed, the MOTSTOP status signal will go HIGH and switch the motor

servo to off mode.

Off mode Motor not steered.

POWER LIMIT

In Start mode 1, Start mode 2, Stop mode 1 and Stop

mode 2, a fixed positive or negative voltage is applied to

the motor. This voltage can be programmed as a

percentage of the maximum possible voltage via the motor

output configuration register (address 0110) to limit

current drain during start and stop. The following power

limits are possible:

•100% of maximum (no power limit)

•75% of maximum

•50% of maximum

•37% of maximum.

LOOP CHARACTERISTICS

The gain and cross-over frequencies of the motor control

loop can be programmed via the motor gain and bandwidth

registers (addresses 0100 and 0101). The possible

parameter values are as follows:

Gain: 3.2, 4.0, 6.4, 8.0 12.8, 16, 26.6 or 32.

Cross-over frequency, f4:−0.5, −0.7, −1.4 or −2.8 Hz.

Cross-over frequency, f3:−0.85, −1.71 or −3.42 Hz.

FIFO OVERFLOW

If FIFO overflow occurs during Play mode (e.g. as a result

of motor shock), the FIFO will be automatically reset

to 50% and the audio interpolator is activated to minimize

the effect of data loss.