HA12179F Просмотр технического описания (PDF) - Hitachi -> Renesas Electronics

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HA12179F

Audio Signal Processer for Car Deck and Cassette Deck (Dolby B-type NR with PB Amp)

Hitachi -> Renesas Electronics 

HA12179F

Input Block Diagram and Level Diagram

R34

5.1k R35

5.1k

EQ OUT

C24

0.1µ

TAI

R38

330k

R39

180

R36

30mVrms

12k EQ OUT-M (–28.2dBs)

R37

18k

EQ AMP.

C25

0.01µ NFI

–+

RIN

VREF

0.6mVrms

(–62.2dBs)

FIN

HA12179F : 387.5mVrms (–6.0dBs)

PBOUT

INPUT AMP

+

–

NR circuit

RECOUT

300mVrms

(–8.2dBs)

Note: The each level shown above is typical value when offering PBOUT level to PBOUT pin. (EQ AMP.)

Gv = 40 dB, f = 1 kHz

Figure 3 Input Block Diagram

Adjustment of Playback Dolby Level

After replace R34 and R35 with a half-fix volume of 10 kΩ, adjust RECOUT level to be Dolby level with

playback mode.

Note on Connecting with Tape Head to IC

This IC has no internal resistor to give the DC bias current to equalizer amp., therefore the DC bias current

will give through the head. This IC provides the Vref buffer output pin for Rch and Lch separately (has

two Vref terminal). In case of use that the Rch and Lch reference of head are connected commonly, please

use one of Vref terminals of IC (47 pin or 52 pin) for head reference.

If both 47 pin and 52 pin of IC are connected, rush current give the great damage to IC. The application

circuit is shown in figure 4.

Rev.1, Apr. 1994, page 12 of 40

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