HA12215 Просмотр технического описания (PDF) - Hitachi -> Renesas Electronics

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HA12215

Audio Signal Processor for Cassette Deck (Dolby B-type NR with Recording System)

Hitachi -> Renesas Electronics 

HA12215F

BIAS (N) R21

Pin 33

BIAS (C) R20

Pin 32

BIAS (M) R19

Pin 31

Vbias

R22

VEE

Figure 10 External Components of Bias Block

Automatic Level Control

ALC is the input decay rate variable system. It has internal variable resistors of pin 55 (pin 44) by

RECOUT signal that is inputted to pin 9 (pin 34).

The operation is similitude to MS, detected by pin 13.

The signal input pin is pin 56 (pin 43). Resistor R1, R2 and capacitor C2, external components, for the

input circuit are commended as figure 12. There are requested to use value of the block diagram figure for

performance maintenance of S/N, T.H.D. etc.

Figure 11 shows the relation with R1 front RIN point and ROUT.

ALC operation level acts for the center of +4.5 dB at tape position TYPE I, IV and the center of +2.5 dB at

tape position TYPE II, to standard level (300 mVrms).

Then, adopted maximum value circuit, ALC is operated by a large channel of a signal.

ALC ON/OFF can switch it by pin 15. Please do ALC ON, after it does for one time ALC OFF inevitably,

for ALC time to start usefully (when switching PB → PASS, when switching PB → PASS), in order to

reset ALC circuit.

300mV

TYPE I, IV

TYPE II 4.5dB

2.5dB

RIN

Figure 11 ALC Operation Level

Rev.5, Oct. 1999, page 15 of 69

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