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5.1.2 PHOTO DIODE SIGNAL PROCESSOR
TDA3808
The TDA88'8 is a bipolar integrated circuit designed for use
in compact tisc players with a single spot read out system.
It amplifies he photo-diodes signals and processes the error
signals for the focus- and radial control circuitry.
Also built-imthe laser supply, focusnormalizing circuit and
focus startirg circuit.
ABBREVIATON PIN
DESCRIPTION
NBR
DEC
28
Decoupling input (Internal bypass)
HF IN
26
HF current input to HF amplifier
D1 - D4
22 -
Current inputs to DC and LF photo
25
diode amplifier.
RE1
21
'Radial Error signal 1 ( summation of
amplified currents D3 and D,.)
RE2
20 _~— Radial Error signal 2 { summation of
amplified currents D, and Do.)
GCLF
19
Gain control input for AC and LF
amplifiers. Current output from LF
amplitude detector.
LM
18
Laser Monitor diode input
LO
17
~ Laser amplifier current output
FE lag
16
Focus Error signal output for LAG
network.
FE
15
Focus Error signal output.
Low Pass filter.
Neg. Supply for FE and FE lag
output stage.
CLPF (LPF)
14
VBB (Vext)
13
bewece
PCS 66 391
DODS (DODS)
12
TL(TL)
1
HFD (PLLH)
10
FS(FOC Start)
9
BGC
8
BEQ
7
SV/RD(SVRD)
6
SC
5
DET
4
HFout
3
Vp
2
GCHF
1
Drop Out Detection Suppression
input
Track Lost output
High Frequency Detector output
Focus normalizing circuit starting
current.
DC and LF gain control ref.input.
Equalizer reference current input.
On/Off control for laser supply and
focus circuit. Ready Signal, starting
up procedure succesful.
Starting up capacitor input.
HF detector voltage input.
HF amplifier and equalizer voltage
output.
Positive supply voltage
Gain Control input of HF amplifier.
Current output from HF amplitude
detector
TO DECODER
TO MICROCONTROLLER
FROM MICROCONTROLLER:
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