saa7803 NXP Semiconductors, saa7803 Datasheet - Page 13

• Manufacturer Part Number: saa7803
• Description: Saa7803 One Chip Cd Audio Device
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 13695
Objective data sheet
6.5 AHB core clock generation
Since these two inputs share one pair of the LF sigma-delta ADCs used in the LF path (for
inputs D1 and D2) a multiplexer is used to control the data source into the ADCs. For this
reason, D1 and D2 cannot be used at the same time as AUX_IN_L and AUX_IN_R. A
further multiplexer is used to switch the input pads from the headphone input buffer modes
to auxiliary input modes. This path has a specification of SNR = 55 dB and THD < 0.3 %
and can be used for tuner input processing. These performance figures are below that
available when the normal CD-Audio path is used i.e. SNR > 80 dB and THD < 0.01 %.
Please ensure that the signal applied to the auxiliary inputs is bandwidth limited to 20 kHz
or aliasing may occur. The auxiliary inputs do have an adjustable second order anti-alias
filter, but, please be aware that this may not provide enough stop band rejection in all
cases.
The audio data is converted to a pulse density modulated digital stream for both input
channels. This data is then low-pass filtered and decimated to produce 10-bit
representations of the analog inputs.
The auxiliary input is different from the general purpose analog inputs in that the parallel
data is converted to an I
which makes the data available to the ARM microprocessor. The I
a variable size data FIFO which means the ARM microprocessor does not have to service
the audio data with as high a priority as it would if it were directly registered. See
Two independent clock dividers are used within SAA7803, one for CD-Slim and the other
for the ARM Advanced High performance Bus (AHB) core.
description of the SAA7803 clocking, AHB fixed clock frequencies are given. A more
detailed description of the CD-Slim clocking is given in
Rev. 01 — 19 April 2005
2
S-bus format stream and then sent to the I
Figure
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
Figure 8
One chip CD audio device
10.
2
S-bus handler contains
2
gives a top level
S-bus handler block
SAA7803
Figure
13 of 74
7.