2
CX-961
1. CIRCUIT DESCRIPTIONS
This unit is roughly divided into the preamplifier stage, servo unit, power supply unit and loading control unit. This
LSI (large scale integrated circuit) implements eight automatic adjustments according to the combination of the
preamplifier stage and servo unit used.
Besides, because this system conforms to the single power supply (+5 V) specifications, the reference voltages of
servo systems (preamplifier, servo DSP and pickup) are all Vref (2. 1 V).
1.1 Preamplifier (TA2150FN; IC201)
The preamplifier processes output signal from the
pickup, then generates signals to the servo unit,
demodulator unit and control unit at the next stage, and
controls power for the pickup’s laser diode. The signal
from the pickup is I-V converted by the preamplifier
built into the pickup’s photodetector, then added by the
RF amplifier to obtain such signals as RF, FE and TE.
Reference voltage Vref (2.1 V) is output from pin 19 of
this IC and 2 Vref (4.2 V) is supplied as the reference
voltage which determines the D range of the servo DSP
A/D input.
Fig.1:TA2150FN CIRCUIT
