Pin Function
Pin No. Pin name
1 SIF INPUT
LA75525AVA
Function
SIF input. The input impedance is about 1kΩ. Since buzzing and
buzz beating can occur if interference enters this input pin, care
must be taken when design the pattern layout for this pin. Note
that the video and chrominance signals are especially likely to
interface with the audio signal. Also, the VIF carrier signal can
also cause interference.
By SW1, Gain at the time of Intercarrier and Split system is
switched.
Equivalent circuit
VCC
200Ω 1kΩ
200Ω 1kΩ
2 FM BIAS
FILTER
FM detector bias line filter input.
Used to improve the FM detector signal-to-noise ratio.
C1 should be at least 0.47µF, and 1µF is recommended.
If the FM detector is not used, connect pin 2 to ground through a
2kΩ resister. This stops the FM detector VCO.
SW1
1
3.6V
5kΩ
5kΩ
2
C1
4kΩ
7kΩ
3 SIF CARRIER SIF carrier output.
OUTPUT
A 200Ω resister is inserted in series with an emitter-follower
output.
200Ω
3
4
VCC
5 VIDEO OUT
6 EQ FILTER
7 EQ INPUT
Use the shortest distance possible when decoupling
Capacitors VCC and ground.
Equalizer circuit. This circuit is used to correct the video signal
frequency characteristics.
Pin 7 is the EQ amplifier input.
Notes on equalizer amplifier is designed as a gain of about 0dB.
when user for frequency characteristics correction, a capacitor,
inductor, and resistor must be connected in series between pin 6
and ground.
Approach used in the equalizer amplifier If Vi the input signal and
VO is the output signal, then:
R1
2
+
1(Vi
+
Vin)
=
VO
×
G
Where G is the voltage-follower amplifier gain.
Assume:
Vin: Imaginary short
G ≈ 0.
Vin ≈ 0.
Then:
AV
=
VOG
Vi
=
R1
Z
+1
R1 is the IC internal resistance, and is 1kΩ. In the application
design, simply select Z to correspond to the desired
characteristics. However, since the EQ amplifier gain will be
maximum at the resonant point defined by Z, care is required to
assure that distortion dose not occur.
VCC
2kΩ
1kΩ
5
6
C
L
50kΩ
R
200Ω
7
Continued on next page.
No.A1256-6/10