saa7806 NXP Semiconductors, saa7806 Datasheet - Page 20

• Manufacturer Part Number: saa7806
• Description: Saa7806 One Chip Automotive Cd Audio Device
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 13697
Objective data sheet
Fig 12. Signal conditioning
6.6.5.1 Signal conditioning
ANALOG
On the sampled HF, bit recovery is done by a full digital PLL and slicer.
Before the sampled signal enters the PLL section, it is preprocessed by a signal
conditioning block. This consists of an integrate and dump block, a high-pass filter and
logic for gain control and offset control on the RF-signal in the analog section.
For good playability on defects, a defect detector is used to hold the PLL, slicer, AGC,
offset cancellation and high-pass filter during defects.
The detected bits are then sent to the demodulator for sync extraction and EFM
demodulation. For playing on damaged or out-of-spec disks, flywheels are used to make
the sync extraction more robust.
This device has a number of blocks which process the incoming 6-bit HF-signal:
All blocks can be configured under microcontroller control.
Integrate and dump block:
one sample every hf_clk period). The sample rate needs to be adapted from this xclk rate
to the lower sysclk rate. For more information on sysclk speed, see
control” on page
•
•
•
•
•
•
Integrate and dump block to adapt the frequency of the AD converter to the system
clock
Peak detection logic for amplitude measurement
Peak detection logic for DC offset measurement
Digital high-pass filter with configurable cut-off frequency
DC and gain control logic for on-board variable gain and offset control (in the analog
section)
A defect detector.
ADC
17.
DUMP
INT/
DETECTOR
PEAK
Rev. 01 — 20 June 2005
AGC
AOC
The ADC delivers one sample every xclk period (equal to
MEASUREMENT
HIGH-PASS
OFFSET
FILTER
hold
One chip automotive CD audio device
DETECTOR
DETECTOR
DEFECT
PEAK
001aab756
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
Section 6.6.3 “Clock
HF-data
to bit detection
hold signals
to bit detection
SAA7806
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