saa7825 NXP Semiconductors, saa7825 Datasheet - Page 20

• Manufacturer Part Number: saa7825
• Description: Cd Audio Decoder, Digital Servo And Filterless Dac With Integrated Pre-amp And Laser Control
• Manufacturer: NXP Semiconductors

Philips Semiconductors
7.10.1.2
The onboard DAC can also be set to accept serial data
inputs from an external source, e.g. an Electronic Shock
Absorption (ESA) IC. This is known as loopback mode and
is enabled by setting shadow register 7 to 0000. This
enables the serial data output pins (SCLK, WCLK, DATA
and EF) so that data can be routed from the SAA7825 to
an external ESA system (or external DAC).
The serial data from an external ESA IC can then also be
input to the onboard DAC on the SAA7825 by utilising the
serial data input interface (SCLI, SDI and WCLI).
In this mode, a wide range of data formats to the external
ESA IC can be programmed as shown in Table 7.
However, the serial input on the SAA7825 will always
expect the input data from the ESA IC to be 16-bit 1f
the same data format, either I
output format (set by decoder register 3).
Table 7 DAC interface formats
Note
1. In this mode the first 16 bits contain data, but if any of the fade, attenuate or de-emphasis filter functions are activated
2003 Aug 13
REGISTER 3
CD audio decoder, digital servo and filterless
DAC with integrated pre-amp and laser control
then the first 18 bits contain data.
1010
1011
1110
0010
0110
0000
0100
1100
0011
0111
1111
Loopback external data into onboard DAC
FREQUENCY
SAMPLE
4f
4f
4f
2f
2f
2f
f
f
f
f
f
s
s
s
s
s
s
s
s
s
s
s
2
S-bus or EIAJ, as the serial
NUMBER OF
16/18
BITS
16
16
16
18
16
18
18
16
18
18
(1)
s
and
20
7.10.2
Audio data from the SAA7825 can be sent to an external
DAC, identical to the SAA732X series, in ‘loopback’ mode
(i.e. shadow register 7 is set to 0000).
The SAA7825 is compatible with a wide range of external
DACs. Eleven formats are supported and are given in
Table 7. Figures 13 and 14 show the Philips I
the EIAJ data formats respectively. When the decoder is
operated in lock-to-disc mode, the SCLK frequency is
dependent on the disc speed factor ‘d’.
All formats are MSB first and 1f
of the WCLK and the data can be inverted; selectable by
decoder register 7. It should be noted that EF is only a
defined output in CD-ROM and 1f
When using an external DAC (or when using the onboard
DAC in non-loopback mode), the serial data inputs to the
onboard DAC (SCLI, SDI and WCLI) should be tied to
ground.
SCLK (MHz)
2.1168
2.1168
2.1168
2.1168
2.1168
8.4672
8.4672
8.4672
4.2336
4.2336
4.2336
E
XTERNAL
n
n
n
n
n
n
n
n
n
n
n
CD-ROM (EIAJ)
DAC
Philips I
Philips I
Philips I
EIAJ 16 bits
EIAJ 18 bits
EIAJ 16 bits
EIAJ 18 bits
EIAJ 16 bits
EIAJ 18 bits
16/18 bits
FORMAT
CD-ROM
(I
18 bits
18 bits
2
INTERFACE
S-bus)
2
2
2
S-bus
S-bus
S-bus
(1)
s
is 44.1 kHz. The polarity
s
modes.
Objective specification
INTERPOLATION
SAA7825
2
yes
yes
yes
yes
yes
yes
yes
yes
yes
S-bus and
no
no