SAA7372 Datasheet, PDF (20/60 Pages) NXP Semiconductors – Digital servo processor and Compact Disc decoder CD7

Philips Semiconductors
Digital servo processor and Compact Disc
decoder (CD7)
Product specification
SAA7372
7.12 The VIA interface
The SAA7372 has five pins that can be reconfigured for different applications (see Table 8).
Table 8 Pin applications
PIN NAME
PIN
NUMBER
V1
62
V2
63
V3
42
V4
41
V5
40
TYPE
input
input
output
output
output
CONTROL
REGISTER
ADDRESS
1100
−
−
1100
−
−
1101
−
−
−
1101
−
−
CONTROL
REGISTER
DATA
xxx1
xxx0
−
xx0x
x01x
x11x
0000
xx01
xx10
xx11
01xx
10xx
11xx
FUNCTION
external off-track signal input
internal off-track signal used, input may be read
via decoder status bit; selected via register 2
input may be read via decoder status bit;
selected via register 2
KILL output for right channel
output = 0
output = 1
4-line motor drive (using V4 and V5)
Q-to-W subcode output
output = 0
output = 1
de-emphasis output (active HIGH)
output = 0
output = 1
7.13 Spindle motor control
7.13.1 MOTOR OUTPUT MODES
The spindle motor speed is controlled by a fully integrated
digital servo. Address information from the internal
±8 frame FIFO and disc speed information are used to
calculate the motor control output signals. Several output
modes, selected by register 6, are supported:
• Pulse density, 2-line (true complement output),
(1 × n) MHz sample frequency
• PWM output, 2-line, (22.05 × n) kHz modulation
frequency
• PWM output, 4-line, (22.05 × n) kHz modulation
frequency
• CDV motor mode.
7.13.1.1 Pulse density output mode
In the pulse density mode the motor output pin (MOTO1)
is the pulse density modulated motor output signal. A 50%
duty factor corresponds with the motor not actuated,
higher duty factors mean acceleration, lower mean
braking. In this mode, the MOTO2 signal is the inverse of
the MOTO1 signal. Both signals change state only on the
edges of a (1 × n) MHz internal clock signal. Possible
application diagrams are illustrated in Fig.13.
7.13.1.2 PWM output mode (2-line)
In the PWM mode the motor acceleration signal is put in
pulse-width modulation form on the MOTO1 output. The
motor braking signal is pulse-width modulated on the
MOTO2 output. The timing is illustrated in Fig.14. A typical
application diagram is illustrated in Fig.15.
1998 Feb 26
20