LA3220 データシートの表示（PDF） - SANYO -> Panasonic

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LA3220

2-Channel Equalizer Amplifier with ALC

SANYO -> Panasonic 

LA3220

The rectification circuit, which obtaines ALC control voltage, should be a voltage doubler with superior compres-

sion ratio. Also, for low voltage 6V sets, etc., a germanium diode is recommended for D1, D2.

2. Closed loop gain VG (f=1kHz)

Closed loop voltage gain is gotten at (f=1kHz) VG ≈ 20log Z1/Z3

If Z1=7.2kΩ

Z3=56Ω

VG=20log 7.2 × 103 /56 becomes=42dB.

Therefore, equalizer response is determined by these constants.

So, playback amp gain is :

a. 20log R1/R3 in low frequency regions

b. 20log Z2/Z3 in high frequency regions

Recording amp gain is

VG=20log R1/R3

3. External constants

External constants are related to the operation starting time

of the amp.

The operation starting time is designed to be within 0.2s,

but in this case it is necessary that the differential TR1

and TR2 is the same in time constant. The condition is :

C1 (R1//R2)=R5 · C3

Example : If C1=220µ, R1//R2=5kΩ, R5=51kΩ

then C3 is 22µF

· C1 is a decoupling capacitor, and its capacity changes the ripple rejection rate. (If capacity is large, ripple rejection

rate is large.) It is also related to the amp operation starting time, and when R5, C3 time constant is large, C1 must also

be made large. The recommended value is 220µF.

· C2 is an input capacitor, and more than 4.7µF is recommended.

· C3 is an NF capacitor, and determines the low region cut-off frequency. If C3 is increased, operation starting time

lengthens. 10µF is recommended. The recommended constants therefore are :

R5 (RF) C1 (CD) C2 (IN) C3 (NF)

51k to100kΩ 220µF

4.7µF

22µF

200kΩ

330µF

10µF

10µF

We do not recommended more than 200kΩ for R5 which lengthens amp operation starting time.

4. Notes on Use

1) Oscillation

When the amp closed loop gain is lowered, oscillation will occur, so

when using it with under 40dB gain, connect 10pF between pin 3 and

pin 2, and 0.033µF (mylar) + 10Ω to the load end. When closed loop

gain is below VG=30dB, it should not be used.

2) Radio Interference Prevention

Connect about 1000pF between input pin (pin 5) and the ground.

3) Maximu Rating

VCC max is VCC=14V, and it should not go over this. The recommended power supply voltage is 5V to 13V.

4) Load Impedance

The total load impedance as seen from the output terminal should not be less than 680Ω.

5) A shrt between pins will cause breakdown or deterioration.

6) A load short will cause breakdown or deterioration.

No.912–5/8

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