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Reference Information
2-2 RF circuit description
2-2-1 RIC1(TA1236F)
TA1236F is combined with TA1253FN, TC9240F and TC90A19F as bipolar IC developed for DVD SERVO system.
Main features include DVD waveform equalizing, CD waveform equalizing, focus error signal generation, 3-beam
tracking error signal generation, laser power control, etc. after receiving the pick-up output converted into I/V.
1. Basic potentiometer
TA1236F uses a single power method and each circuit is based on V
symmetrical about GND for V
and 2V
output(pin18).
REF
2. RF signal
Fig. 2-20 shows the flow of signal generated by the pick-up.
A, B, C, D signals detected from pick-up are converted in to RF signal(A+B+C+D) via RF summing AMP.
RF signal is inputted to RFN(pin55) among input terminals and RFP(pin54) is used for AC ground.
PICK-UP
D
A
PD
C
B
Fig. 2-21 shows the waveform-equalizing block diagram for the RF signal.
It outputs to EQout(pin 46) terminal by initially changing switching AMP gain of DVD and CD, and then
adjusting the level in VCA. It controls VCA gain by means of RF gain(pin 48) and interfaces with PWM signal,
(output from RFGC terminal of TC9420F, via low-pass filter to constitute a loop for adjustment of constant
amplitude). The gain in EQout is 1.0 for DVD and 1.67 for CD.
EQout terminal is connected with EQin(pin 45) externally, and inputs into DVD EQ and CD EQ(Waveform
equalizing circuit).
2-10
because V
REF
REF
RC12
104
RC10
104
RC15
104
RC14
104
I-V AMP
REF
(pin20) terminal is needed for IC, which uses the peripheral V
SUMMING AMP
RR18
1.2K
RR20
RIC3 OPA 650
1K
2
–
3
+
RR19
1K
RR24
1K
RR22
1K
Fig. 2-20
of 2.1V. Note :
RC11
104
6
+5A
RR23
10K
RR50
5.6K
Vref
RR51
5.6K
RC22
104
Vref
Samsung Electronics
REF
55
RFN
RIC1
TA1236
54
RFP
RR33
10K
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