SAF7849HL/M295,557 NXP Semiconductors, SAF7849HL/M295,557 Datasheet - Page 52

• Manufacturer Part Number: SAF7849HL/M295,557
• Description: IC AUD DECODER 144LQFP
• Manufacturer: NXP Semiconductors
• Type: Audio Decoderr

Specifications of SAF7849HL/M295,557

• Applications: Audio CD
• Voltage - Supply, Analog: 3 V ~ 3.6 V
• Voltage - Supply, Digital: 1.8V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 144-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 935287932557

NXP Semiconductors
SAF784X_2
Product data sheet
6.6.3 Signal conditioning
The digital codes retrieved from the ADC and PDM generator are applied to logic circuitry
to obtain the various control signals. The signals from the central aperture diodes are
processed to obtain a normalized focus error signal.
where the detector setup is assumed to be as shown in
For the single foucault focusing method, the signal conditioning can be switched under
software control such that the signal processing is as follows:
The error signal, FE
filter section.
An internal flag is generated by means of the central aperture signal and an adjustable
reference level. This signal is used to provide extra protection for the Track Loss (TL)
generation, the focus start-up procedure and the dropout detection.
The radial or tracking error signal is generated by the satellite detector signals R1 and R2.
The radial error signal can be formulated as follows:
RE
where the index ‘s’ indicates the automatic scaling operation which is performed on the
radial error signal. This scaling is necessary to avoid non-optimum dynamic range usage
in the digital representation and reduces the radial bandwidth spread. Furthermore, the
radial error signal will be made free from offset during start-up of the disc.
The four signals from the central aperture detectors, together with the satellite detector
signals generate a Track Position Indicator signal (TPI) which can be formulated as
follows:
TPI = sign [(D1 + D2 + D3 + D4)
where the weighting factor sum_gain is generated internally by the SAF784x during
initialization.
FE n
FE n
s
= (R1
=
=
2
---------------------
D1
D1 D2
+
–
---------------------
D1
D1 D2
R2)
D2
+
–
–
D2
---------------------
D3
D3 D4
re_gain + (R1 + R2)
n
, is further processed by a Proportional-Integral and Differential (PID)
+
–
One chip CD audio device with integrated MP3/WMA decoder
D4
Rev. 02 — 9 May 2008
(R1 + R2)
re_offset
sum_gain]
Figure
29.
SAF784x
© NXP B.V. 2008. All rights reserved.
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