Sony CXA1897Q Datasheet

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E93930D78

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Dolby B Type Noise Reduction System with Recording/Playback Equalizer

CXA1897Q

Absolute Maximum Ratings (Ta=25°C)

• Supply voltage VCC 12 V

• Operating temperature Topr –20 to +75 °C

• Storage temperature Tstg –65 to +150 °C

• Allowable power dissipation

PD 735 mW

Operating Conditions

• Supply voltage VCC 6.5 to 10.0 V

Description

The CXA1897Q is an analog signal processing IC
for tape recorders. It achieves whole processing
operations for the recording and playback systems
which include the Dolby B noise reduction function
on a single chip. This IC supports 2 channels at
each function.

Features

• Dolby B noise reduction supports 1.7 times normal

speed.

• Recording/playback equalizer amplifier supports

1.7 times normal speed.

• Built-in comparator for AMS (automatic music

sensor)

• Built-in AGC (automatic gain control) with amplifier

for MPX filter.

• Playback equalizer outputs independently for

DECK-A and DECK-B.

• Externally adjustable recording equalizer Gp and

fp.

• Built-in Recording mute function.

• Double cassette dubbing system can be easily

configured just with this IC.

Applications

All analog signal processing in cassette deck parts
of tape recorders and compact music centers

(Sankyo Seiki mfg. Co., Ltd. YK47R-KF202 or

equivalent which has the same head type.)

Structure

Bipolar silicon monolithic IC

48 pin QFP (Plastic)

∗ These ICs are available only to the licensees of Dolby Laboratories Licensing Corporation from whom licensing and applications

information may be obtained.

∗ "Dolby" and the double D symbols are trade marks of Dolby Laboratories Licensing Corporation.

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CXA1897Q

Block Diagram

AMS
OUT

GND

D PB IN1

DOLBY NR
ON/OFF/HI

D L OUT1

Vcc

Vcc

AGC IN

GND

+

+

AMS GAIN

GND

MPX

D REC IN1

GND

D IREF

GND

RFC

AGC

+

OUT

TC

DECK A

PB FB11

PB HEAD

GND

PB INA1

PB INB1

PB INB2

PB INA2

GND

++

PB FB12

GND

++

PB OUTA2

PB FB22

PB OUTB2

GND

PB OUTB1

GND

PB OUTA1

PB FB21

373839404142434445464748

GND

GND

GND

1
2
3

10dB

AMP

IREF

AGC

IREF

AMS

4

+

10k

5

40k

6
7
8

+ +

9

10
11
12

NR

REC

EQ

PBEQ

CTL

GND

GND

MUTE

REC

EQ

RECEQ

CTL

GND

10dB

AMP

40k

NR

Vcc

GND

10k

GND

36
35

IREF

34

VG

33

+

32
31

AGC
OUT

30

D REC IN2

29

+ +

28
27
26
25

TC

GND

++

AGC TC

GNDGND GND

AGC IN

MPX

+

+

GND

REC
MUTE

GND

D PB IN2

DOLBY NR
REC/PB

D L OUT2

GND

GND

13

+

D R OUT1

GND

GND

+

DECK

REC IN

PB

REC

(120/70us)

DECK

A EQ

A/B

(N/Cr/Me)

DECK B EQ

REC OUT1

DECK B

R/P HEAD

++

REC OUT2

FP CAL

SPEED

GNDGND

PB

REC

+

GP CAL

GNDGND

REC IN

2423222120191817161514

+

D R OUT2

GND

—3—

CXA1897Q

Pin Configuration

37

PB OUTB2

38

PB OUTA2

39

PB FB22

40

PB FB12

41

PB INB2

42

PB INA2

43

PB INA1

44

PB INB1

45

PB FB11

46

PB FB 21

47

PB OUTA1

GND

3536

IREF

34

VG

33

AGC TC

32

AGC IN2

31

30

AGC OUT2

CXA1897Q

29

D RECIN2

REC MUTE

28

D PBIN2

27

MODE

26

25

D L OUT2

D TC2

D R OUT2

REC IN2

GP CAL

FP CAL

SPEED

REC OUT2

REC OUT1

B EQ

A EQ

DECK AB

REC IN1

24

23

22

21

20

19

18

17

16

15

14

48

PB OUTB1

1

Vcc

RFC

AMS OUT

32

4

AMS GAIN

AGC IN1

5

AGC OUT1

6

D RECIN1

D IREF

87

D PBIN1

9

NRSW

10

D L OUT1

11 12

D R OUT1

D TC1

13

—4—

CXA1897Q

Pin Description (Ta=25°C, Vcc=8 V, no signals)

Pin

Symbol

DC

I/O

I/O

Equivalent circuit Description

No. voltage

resistance

1 Vcc 8.0V — —

2 RFC 8.0V — —

3 AMS OUT 8.0V O —

4 AMS GAIN 2.8V — —

5 AGC IN1 4.0V I 50kΩ

32 AGC IN2

Power supply pin.

Connects the resistor and
capacitor for providing a ripple
eliminated stable voltage in
the power supply.

AMS output pin.
Connects the resistor and
capacitor which determine the
attack and recovery time
constants of the output to Vcc.

No signal supplied → High
level
Signal supplied → Low level

Connects the resistor which
determines the AMS signal
detection level.

AGC signal input pin.
The input resistance varies
from 50kΩ to 10kΩ.
AGC is applied when a signal
of –30dB or more level is input
to AGC.
(Pin 33 external 47µF //
300kΩ)

1

Vcc

Vcc

×3

×3

2

147

GND

Vcc

×250

to RFS

Vcc

3

147

×2

GND

Vcc

Vcc

4

32

5

GND

Vcc

GND

147

147

×2

10k

40k

VGS

×4

5p

10k

Vcc

—5—

CXA1897Q

Pin

Symbol

DC

I/O

I/O

Equivalent circuit Description

No. voltage

resistance

6

AGC OUT1

4.0V O 147Ω

31

AGC OUT2

7 D RECIN1 4.0V I 40kΩ

30 D RECIN2

9 D PBIN1 4.0V I 40kΩ

28 D PBIN2

8 D IREF 1.2V — —

10 NRSW 2.5V I 53kΩ

(For

OPEN)

AGC output pin.

Dolby NR recording
(encoding) input pin.

Dolby NR playback (decoding)
input pin.

Connects the 18kΩ resistor for
providing the reference
current of the Dolby NR
section internal filter.

Dolby NR ON/OFF switch.
Low : ON
Medium :OFF
High : 1.7 times normal

speed

Vcc

GND

147

4k

×2

×4

Vcc

8

Vcc

GND

147

50k

5k

5k

10

GND

Vcc

6

31

Vcc

GND

7
9

28

30

147

Vcc

GND

×2

×4

147

40k

500
500

VGS

15k

21k

10k

5k

Vcc

15k

Vcc

VGS

VGS

—6—

CXA1897Q

Pin

Symbol

DC

I/O

I/O

Equivalent circuit Description

No. voltage

resistance

11 D L OUT1 4.0V O 147Ω
26 D L OUT2

12 D TC1 0.3V — —
25 D TC2

13 D R OUT1 4.0V O 147Ω
24 D R OUT2

14 REC IN1 4.0V I 50kΩ
23 REC IN2

Dolby NR line (decoding)
output pin.

Connects the capacitors
(0.1µF) which determine the
time constants of the input
signal level detector.

Dolby NR recording
(encoding) output pin.

Recording equalizer input pin.

11
26

Vcc

147

×2

200
200

×10

Vcc

6k

12
25

GND

Vcc

×2

20k

147

700k

GND

Vcc

GND

GND

14
23

13

24

Vcc

GND

Vcc

GND

147

×10

147

×2

50k

300
300

VGS

Vcc

10k

13k

GND

Vcc

23k

1.8k

VGS

GND

—7—

CXA1897Q

Pin

Symbol

DC

I/O

I/O

Equivalent circuit Description

No. voltage

resistance

15 DECK AB — I —
16 A EQ
20 SPEED
27 MODE

17 B EQ 2.5V I 53kΩ

(For

OPEN)

18 REC OUT1 4.0V O 147Ω
19 REC OUT2

15

Playback input deck A/B
selector switch
Low : PB INA
High : PB INB

16

Deck A equalizer selector
switch.
Low : 120µs EQ
High : 70µs EQ

20

Recording/playback
equalizer speed selector
switch.
Low : Normal speed
High : High speed
(1.7 times normal speed)

27

Dolby NR mode selector
switch.
Low : Recording

(encoding)

High : Playback (decoding)

Deck B equalizer selector
switch.
Low : Normal tape, 120µs

EQ
Medium :CrO2 tape, 70µs EQ
High : Metal tape, 70µs

EQ

Recording equalizer output.

Vcc

GND

147

50k

5k

5k

GND

Vcc

17
19

Vcc

GND

147

500

GND

Vcc

500

×3

×10

×2

40k

5p

18

Vcc

Vcc

15
16
20
27

147

GND

GND