SAF7849HL/M295,557 NXP Semiconductors, SAF7849HL/M295,557 Datasheet - Page 11

• 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
6.1.2 HF acquisition
The HF data (EFM) signal is obtained by summing the signals from the three or four
central diodes of the OPU and filtering and converting the signals to a digital
representation via a 6-bit HF ADC.
path.
The four diode signals D1, D2, D3 and D4 are summed in the first RF amplifier. The gain
of the first amplifier is controlled by register AGCGain[7:4].
A second gain stage has been added to lessen the gain bandwidth requirements of a
single gain stage operational amplifier and also to act as dynamic Automatic Gain Control
(AGC). The gain of this amplifier is set by register AGCGain[3:0] and can be changed
on-the-fly from the ARM microprocessor. The gain range accommodates 12 dB of gain
needed to boost the signal when the laser tracks across a fingerprint defect on the disc.
CD-R, CD-RW, and finger prints, not only reduce the AC signal amplitude compared to a
perfectly pressed disc but also reduces the DC pedestal voltage. The high-pass filter will
remove all DC present at the input, but offsets will be added by the second and third gain
stages. A 5-bit plus-sign DAC controlled by register OffsetComp[5:0] adds a current to
compensate for this offset. The current reduces in linear dB steps and follows the AC gain.
Fig 4.
register
RFControl2[1]
HF_MON
RFControl2[5]
register
HF acquisition block diagram
D1
D2
D3
D4
decoded to [31:0]
OffsetComp[5:0]
RFControl2[3]
20 k
20 k
20 k
20 k
20 k
20 k
20 k
register
register
RFControl2[1]
One chip CD audio device with integrated MP3/WMA decoder
Rev. 02 — 9 May 2008
register
register AGCGain[7:4]
0 dB ... 24 dB
RF AMP1
H
RFControl2[2]
single-ended-to-
register
Figure 4
4
G
differential
converter
80 k
80 k
A
E
HIGH-PASS
D
shows a simplified block diagram of the HF
FILTER
D
E
C
RFControl1[3:0]
noise_filt_sel
B
FILTER
register
NOISE
B
A
67.7376 MHz
register
RFControl1[6:4]
register AGCGain[3:0]
from PLL
G
H
0 dB ... 12 dB
RFControl2[0]
RFControl2[4]
RF AMP2
register
register
SAF784x
© NXP B.V. 2008. All rights reserved.
rf_adc_out[5:0]
to channel decoder
67.7376 MHz
sys_clk
C
001aag308
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