cxa1202q-z Sony Electronics, cxa1202q-z Datasheet - Page 18

• Manufacturer Part Number: cxa1202q-z
• Description: Rec/pb Amplifier For Vcr
• Manufacturer: Sony Electronics

[Head AMP]
The playback signal from the head is amplified with low noise and high gain. For example, the equivalent input
noise level at 1MHz is 662pVrms/
In PB, the total input capacitance
head inductance, a feedback dumping is incorporated.
Connect a bypass capacitor for PB IN 1N and PB IN 2N pins between these pins and the rotary transformer
Vcc. So far as this capacitor is over 0.2µF, the low-Ievel frequency response does not deteriorate. Beside the
0.1µF good frequency response capacitor connected to pin VREG, by adding a capacitor of over 10µF,
degradation of noise level at low range can be prevented.
Take care not to allow capacitance coupling between PB output and Head AMP input.
[Medium range frequency compensation circuit + SW]
This corrects the frequency response of the PB signal. It is possible to set to and Q magnitude by means of the
external resistance value of MT F and MTQ pins (refer to the F graph). The amount of boost may be
adjusted through the external volumes of MT1 and MT2 pins (refer to the graph showing the effect of standard
response MT2 pin voltage on the amount of boost).
By controlling the control logic section, SW is changed over with the timing of RF SW (switching pulse), to
output PCM RF signals and VIDEO RF signals. Mute is applicable to VIDEO RF signals during PCM after
recording within the PCM recording area period.
[RF AGC]
The played back VIDEO RF signal are output here to achieve a constant level of 100mVp-p. The time constant
for AGC is set by means of the resistance and capacitance external to AGC TC pin.
At the input section of the detector a HPF with a cutoff frequency of about 1MHz is incorporated. This is to
permit detection within the Y signal band.
In PCM after recording, MUTE applies during the PCM recording area period to keep the gain on an
unchanged level.
[RF SW]
Signals input to RF IN A and RF IN B pins are selected by means of HCHG control signals and output via the
12-dB amplifier to RF OUT pin. This switch is utilized for SP/LP head changeover when a 4-head system is
employed.
[Dropout detection]
Dropout is detected here from RF signals of played-back VIDEO and dropout pulse is output. The time
constant is set by means of the external resistance and capacitance external to DOC TC pin.
The detection level is set in the interior with 400mVp-p input as standard to obtain optimum level.
Use an external coupling capacitance value of input of 47pF to achieve HPF function.
[Control Logic]
The IC is controlled from this section as it will save power when circuit blocks are not in use. Therefore, power
saving is automatically executed while all the power supplies are switched on. Many SWs are also available to
switch inputs or outputs with complicated timing. Internal logic circuits to control them are provided.
It is possible to achieve all possible combinations of inputs/outputs necessary for the basic operations by
means of the 13 modes shown in the Control Logic Truth Table.
L is set when the control logic pin is open.
[Standard voltage supplies in the IC]
VREG 4.2V and VG 2.5V are provided as the standard voltage supplies in the IC.
1
and
2
See the next page.
2
Hz.
will be about 75pF. To inhibit resonance between this capacitance and the
1
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CXA1202Q-Z/CXA1202R