LA3410 データシートの表示（PDF） - SANYO -> Panasonic

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LA3410

VCO Non-Adjusting PLL FM MPX Stereo Demodulator with FM Accessories

SANYO -> Panasonic 

LA3410

(2) PLL loop filter constants

(a) The capture range of the LA3410 depends pri-

marily on input pilot level and PLL loop filter

constants C9 and R8 as shown in Fig. 4-A.

It is necessary to set C9 and R8, with the in-

put pilot level considered, so that the capture

range becomes wide but the stereo distortion

is kept rather low. The transfer function of the

loop filter is given by :

Lag

filter

F

(S)=

1

SC9R0+1

Lag Lead filter F (S)= SC10R8+1

SC10 (R0+R8)+1

R0 : IC internal resistance

and the response is given by Fig.4-B. The cap-

ture range may be made wide by the follow-

ing methods.

¡ Set 3 high to make the band width wide (De-

crease C9).

™ Increase the high frequency gain F (∞) so long

as the characteristic of the Lag Lead filter is

not lost (Increases R8).

Fig. 4-C shows the capture range characteris-

tic when C9 and R8 are varied. When R8 is

increased, the capture range will increase to a

certain point. R8 must be set in this range.

When R8 is increased, the STEREO-L, R dis-

tortion may worsen at low frequencies (100

to 400Hz). In this case, connect a capacitor of

200 to 1000pF across pin 3 and GND to im-

prove the STEREO-L, R distortion (Refer to

Fig. 5).

(3) Fig. 4-D shows the capature range characteris-

tic when C10 is varied. The adequate value of

C10, which depends on C9 and R8, is 0.33 to

3.3µF. If the value of C10 is decreased too

much, the capture range will decrease as seen

from Fig. 3 ; and if increased too much, the

stereo start time after VCO STOP release will

be made late.

No.1407–6/13

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