SAF7849HL/M295,557 NXP Semiconductors, SAF7849HL/M295,557 Datasheet - Page 23

• 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
The high-pass filter works on the system clock. Its bandwidth is also proportional to the
sysclk.
A formula for approximating the cut-off frequency (f
Peak Detectors:
Both peak detectors monitor the RF after it has passed an optional noise filter. This noise
filter is a LPF with a programmable high cut-off frequency. This bandwidth is programmed
via register PDBandwidth bit NOISEFILTERBW for the noise filter before the peak
detectors of AGC/AOC and measurement read back. The defect detector peak detector
has its own noise filter which is programmed via register DefectDetPeakBW bit
NOISEFILTERBW.
Peak detector with decay filter:
in
The maximum and minimum peaks of the incoming signal are measured at the inputs of
switches S1 and S2 respectively. The maximum and minimum peak signal paths both
have a decay filter with a long time-constant and matching bandwidth. The maximum peak
decay filter responds to the smallest value possible. The decay filter for the minimum peak
responds to the largest value possible.
The decay bandwidth of the measurement readback decay filter is controlled by register
PDBandwidth bit DECAYBW, the bandwidth of the defect detector is controlled via register
DefectDetPeakBW bit DECAYBW.
The following settings of the decay filters are possible: C = 1
f
C = time-constant coefficient, m = DecayBW[3:0] + 6.
Fig 12. Peak detection block with decay filter
c HPF
•
•
Figure
peak detector with decay filter: works on an immediate attack/slow-decay basis, and
is used for measuring peaks, amplitude and offset, read by software which sends
peak information to the defect detector.
peak detector based on window: works on the principle of detecting maximum and
minimum peaks within a window, and is used for the AGC and AOC control logic.
(1) Determines the time-constant coefficient.
=
12.
HPSet 5:0
----------------------------- -
2
2
The signal conditioning block has two types of peak detector:
11
HF_in
One chip CD audio device with integrated MP3/WMA decoder
Rev. 02 — 9 May 2008
f
clk sys
FILTER
NOISE
The functional schematic of this peak detector is shown
S1
S2
(1)
(1)
DECAY
FILTER
DECAY
FILTER
c
), of the high-pass filter is:
max peak
min peak
001aag316
2
m
, for m = 6 to 21, where
SAF784x
© NXP B.V. 2008. All rights reserved.
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