Sony CXA1797Q Datasheet

CXA1797Q

Dolby B-C Type Noise Reduction System with Recording Equalizer Amplifier

Description

The CXA1797Q is an audio signal processing LSI

designed for use in cassette decks.

Functions include Dolby B-C noise reduction, recording equalizer amplifier, meter circuit (logarithmic), bias control circuit, and playback switching circuit. Serial control of these functions is possible.

64 pin QFP (Plastic)

Features

• Few external parts

• Serial control of each functions possible

• Dolby B-C noise reduction

• Dolby S noise reduction select switch

• Recording equalizer amplifier

• Recording volume control

• Playback input select switch

• Meter circuit (logarithmic wave detection)

• Bias control circuit (left and right independent)

Applications

Cassette decks

Absolute Maximum Ratings (Ta=25°C)

• Supply voltage VCC +12 V

(between VCC and VEE)

• Operating temperature Topr –20 to +75 °C

• Storage temperature Tstg –65 to +150 °C

• Allowable power dissipation

PD 1.02 W

Recommended Operating Conditions

Supply voltage VCC ±5.25 to ±6.0 V

Structure

Bipolar silicon monolithic IC

∗This IC is 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.

Sony reserves the right to change products and specifications without prior notice. This information does not convey any license by any implication or otherwise under any patents or other right. Application circuits shown, if any, are typical examples illustrating the operation of the devices. Sony cannot assume responsibility for any problems arising out of the use of these circuits.

—1—

E94X42-TE

Block Diagram

C10

CXA1797Q

-EQ

PB

[ DECK-B ]

REC/PB HEAD

Bias

OSC

L2

C20

220p

C19 R62

-4dBv

REC O UT

(B)

VSG

Gm5

40k

R51

-8dBv

×1

200p

C14

(A)

GND

Gm2

10.3k

-9.6dBv

R39

GND

2.2µ

22k

0.68µ

3.9k

C11

R30

R29

2.2µ

8.2k

R28

C9

10k

R37

REC

-4. 7dB v 50k

REC-E Q IN

R31

VGS

-23dBv

Dolby

(-6dBm)

REC O UT

S IN

Dolby

S-N R

MOA

OUT

(-6dBm)

MOA

PB

REC

REC/PB

2.2µ

2k

-26dBv

R18

R17

GND

TO LINE IN

10k

600

GND

-6dBv

OSC

REC I N

Dolby

C6

6.2k

Filt er

MPX

3.3k

R13

-14dBv

∗Source Impedance 10kΩ

(-30dBm)

40k

R16

VGS

(C)

-26dBv (-25dB m )

VOL OUT

-10dBv

6.5k

RVA

R11

R8

BUF OUT

6.5k

-10dBv

×1

50k

R7

LINE IN

-10

dBv

C3

2.2µ 180k

R3

22k

R2

GND

L-ch

LINE IN

REC

PB

10mH

DV

REC/PB

CC

GND

10k

4.7µ

50k

R55

REA

(C)

+6dBv

×1

VGS

Gm4

100p

C16

24k

R50

8k

R49

VGS

(C)

2.8k R38

(A)

GND

BPF

C15

×1

20k

R46

R47

-6dBv

(0dBm)

Gm3

VGS

(C)

-7dBv

(-6dBm)

SSW

BC/S

S-NR

B/C

NR

12k

22.5k

R27

REC

R26

REC/ P B

PB 40k R22

VGS

(-6dBm)

MOA

REC

REC/PB

1.5k

1.5k R23

R24

VGS

(C)

PB

VGS

REC

(C)

REC/ P B

R20

PB

OFF/ON

B/C

BC/S

REC/PB

NOR/CAL

A/B

OFF/ON

120µ/70µ

OFF/ON

NORM/HIGH

OFF/ON

Dolby-NR

METER

PB-DECK

LINE-MUTE

Tape-EQ

METAL

SPEED

VGS

(C) (B)

Gm1

VGS

REC-MUTE

CONTROL

VGS(C)

R-ch

BALANCE

DAT A

CLK

REC LEV E L

LAT CH

50k

R4

CC

50k

DV

R1

for R-ch

GND

100p

(C)

R63

50k

GND

R61

50k

R56

50k

GH CAL

FQ CAL

REC CAL

BIAS OUT

CC

V

Bias

BVG

CALIBR AT ION

GND ( A )

600 22k 130k

22k

R57 R58 R59 R60

VEE

BIAS-C

BIAS-N

BIAS-M

2

NORM

EQ

CrO

150

METAL

VEE

1.25v

0dB= 2. 4v

R54

MTR

R53

METER OUT

C17

76k

100p

4k

R52

DGND

17k

R44

10k

R40

-1dBv

METE R

R34

8.5k R45

7.5k

Gain 12dB up

2.5k

-1dBv

(C)

R32

VGS

R35

LINE

METER AC

(0dBm)

-1dBv

LINE OUT

8k

R33

(B)

-7dBv

(-6dBm)

SSW

BC/S

S-NR

B/C NR

ANTS

LLS VF

R25 12k

R21

22.5k

R19

1.5k

VGS

(C)

HLS VF

Dolby B/ C-NR

SSK

VGS

Dolby

TC2

Dolby

TC1

(-30dBm)

-31dBv

Dolby PB IN

PB OUT

-21dBv

PRE

B DECK

XRESET

BIAS

A DECK

CC

V

VCC

CC

DV

VEE

REC/PB IREF

GND(VG)

R6

27k

VEE

GND

PB IN1

DGND

-21dBv

DOLBY IREF

20k

R5

C2

EE

CC

V

GND

PB

DV

-EQ

50k

DECK A / B

50k

R10

R9

VGS

2.2µ

VGS

(C)

PB IN2

-21dBv

C1

2.2µ

GND

HEAD

PB Only

to Control IC

[ DECK-A ]

VM

10k

GND

-6dBv

Fr om LI NE O UT

∗Load I m pedanc e 47k ohm

to METER IC

3.3µ

C18

GND

DGND

HAEDPHONES

for R-ch

1.0µ C13

R42

4.7µ

C12

R36

GND

R48

220

GND

Amp

HP

10k

R43

GNDGND

4.7k

100k

R41

7.5k

for R-ch

GND

-6dBv

L-ch

R-ch

LINE OUT

0.068µ

C8

0.1µ

EE VEE

C7

V

2.2µ

C5

10k

R15

R12

4.7k

(C)

390p

5.6mH

L1

C4

GND

22k

R14

GND

—2—

CXA1797Q

CC

DV

V

32

31

METE R O UT2

33

S TC

34

RECMUTE TC

35

BIAS2 OUT

36

BIAS2 NORMAL

37

BIAS2 CrO2

38

BIAS2 METRL

REC ED O UT2

METE R TC2

REC EQ IN2

REC OUT2

DOLBY S IN2

DOLBY OUT2

LINE OUT2

DOLBY TCL2

DOLB Y TCH2

REC IN2

VOLUME OUT2

BUFFE R O UT2

BIAS-SW

39

40

41

42

ME TAL

120µ/70µ AMUT E

REC-EQ

SPEED

43

44

45

46

47

48

49

50

VOLUME

51

52

53

FQ CA L

REC CAL

30

29

BALANCE

GH CAL

28

27

REC LEVEL

26

DGND

25

CLK

DATA

24

LATCH

23

22

CONT

PB

S

B/C

METER2

METER1

B/CNM

B/C NR

DOLB Y

CAL

MOA

REC

VC5

PB

REC

LMUTE

LINE

PB

S

B/C

B/CNA

B/C NR

DOLBY

CAL

PB

REC

MOA

VCS

REC

PB

LMUTE

LINE

CXA1797Q

B

A

B

DECK

54

55

56

57

58

A

GND

59

DECK

60

61

62

120µ/70µ AMUT E

63

XRESET

21

ME TAL

SPEED

EE

V

20

METE R O UT1

B/C TC

NR TC

BIAS1 OUT

BIAS1 NORMAL

BIAS1 CrO

BIAS1 METAL

REC EQ OUT1

METE R TC1

BIAS-SW

19

18

17

16

15

2

14

13

12

11

REC-EQ

10

9 8

7 6

5 4

3 2

VOLUME

1

REC EQ IN1

REC OUT1

DOLBY S IN1

DOLBY OUT1

LINE OUT1

DOLBY TCL1

DOLB Y TCH1

REC IN1

VOLUME OUT1

BUFFE R O UT1

64

Pin Configuration

GND

PB IN B1

DOLBY IREF

PB IN A1

PB OUT1

VOLUME IN1

DOLBY PBIN1

PB IN A2

PB IN B2

PB OUT2

VOLUME IN2

DOLBY PBIN2

REC/PB IREF

—3—

CXA1797Q

Pin Description (Ta = 25°C, dual-power supply configuration, VCC = 5.5 V, VEE = 5.5 V, DVCC = 5.0 V)

Pin No. DC AC

1

51

2

50

Symbol

BUFFER OUT1 BUFFER OUT2

VOLUME OUT1 VOLUME OUT2

Typical pin voltage

0.0V

–10dBv

I/O Z (in) Equivalent circuit Description

VCC

500500

O

—

VEE

VCC

6.5k

147

500 500

Recording volume input buffer output

Recording volume output

3

REC IN1

49

REC IN2

4

DOLBY TCH 1

48

DOLBY TCH2

0.0V

VEE

+0.4V

–26dBv (–25dBm)

—

VEE

V

CC

VCT

147

40k

13k

VCC

36k

330k

40kΩ

I

—

Recording input

VEE

Time constant for the HLS

—4—

VEE

CXA1797Q

No. DC AC

5

47

6

46

Symbol

DOLBY TCL1 DOLBY TCL2

LINE OUT1 LINE OUT2

Typical pin voltage

VEE

+0.9V

0.0V

—

–1dBv

(0dBm)

I/O Z (in) Equivalent circuit Description

VCC

—

O

—

VCC

147

13.5k480k

8k

VEE

300300

147

Time constant for the LLS

Line output

7

DOLBY OUT1

45

DOLBY OUT2

8

DOLBY S IN1

44

DOLBY S IN2

0.0V

–7dBv

(–6dBm)

–7dBv

(–6dBm)

O

—

23.5kΩ

VCC

VEE

147

22k

12k

200

147

200

Dolby S NR output

V

CC

Dolby S NR input

—5—

1.5k

VCT

VEE

CXA1797Q

No. DC AC

9

43

10 42

Symbol

REC OUT1 REC OUT2

REC EQ IN1 REC EQ IN2

Typical pin voltage

0.0V

–7dBv

(–6dBm)

–23dBv

I/O Z (in) Equivalent circuit Description

VCC

O

—

VEE

200200 147

VCC

Recording output

Recording

50kΩ

I

147

50k

VCT

VEE

equalizer amplifier input

11

METER AC1

41

METER AC2

12

REC EQ OUT1

40

REC EQ OUT2

0.0V

—

–4dBV

—

O

—

V

CC

VEE

8.5k

50k

200200

147

300300

VCC

DC cut capacitance

VEE

Recording equalizer amplifier output

—6—

CXA1797Q

Pin No. DC AC

13 39 14 38 15 37

16 36

Symbol

BIAS MTL1 BIAS MTL2 BIAS CrO1 BIAS CrO2 BIAS NORM1 BIAS NORM2

BIAS OUT1 BIAS OUT2

Typical pin voltage

VEE

+1.25V

—

I/O Z (in) Equivalent circuit Description

VCC

Recording bias

—

I

147

control voltage setting

VEE

VCC

Recording bias

O

—

147

control voltage output

17

NR TC

18

B/C TC

34

S TC

19

METER OUT1

33

METER OUT2

—

2.4V

—

I/O

O

17kΩ

—

VEE

CC

V

VEE

VCC

DGND VEE

4k

100p

76.6k

14717k

150

Time constant for selecting NR mode Time constant for selecting B/C mode Time constant for selecting S and B/C modes

Meter output (sensitivity: 65 mV/dB)

—7—

CXA1797Q

No. DC AC

20 32

21 22 23

Symbol

VEE VCC

XRESET LATCH CLK

Typical pin voltage

–5.5V +5.5V

—

I/O Z (in) Equivalent circuit Description

Negative power supply (Connect to ground when using

—

I

a single power supply) Positive power supply

VCC

Reset signal input

—

I

2k

2.5V DGND reference

(active low) Load signal input Clock input

DGND

VEE

24

DATA

25

DGND

26

REC LEVEL

—

0V

—

I

—

100kΩ

4k

VCC

DGND

147

VCC

VEE

60k

2.5V DGND reference

Data input

Logic and CAL reference

Recording volume adjustment

—8—

40k

DGND

VEE

CXA1797Q

Pin No. DC AC

27

28 29

Symbol

REC BALANCE

GH CAL FQ CAL

Typical pin voltage

2.5V

—

I/O Z (in) Equivalent circuit Description

VCC

Recording volume balance adjustment

High-frequency

I

100kΩ

VCC

VEE

147

70k

30k

DREF

gain adjustment of recording

54kΩ

I

147 54k

equalizer amplifier Peak frequency Q adjustment of recording

VEE

equalizer amplifier

30

31

REC CAL

DVCC

2.5V

+5.0V

—

CC

V

Recording

54kΩ

I

VEE

CC

V

147 54k

equalizer amplifier gain adjustment

Logic power supply

—

I

30k30k

DREF

(DREF = 1/2 (DVCC + DGND) is CAL reference.)

VEE

DGND

DVCC

—9—

CXA1797Q

No. DC AC

35

52 64

Symbol

RECMUTE TC

LINE IN2 LINE IN1

Typical pin voltage

—

0.0V

—

–10dBv

I/O Z (in) Equivalent circuit Description

CC

V

Time constant for

I/O

17kΩ

selecting RECMUTE mode

17k 147

VEE

VCC

50kΩ

I

147

Recording volume input

53

DOLBY PBIN2

63

DOLBY PBIN1

54

PBOUT2

62

PBOUT1

0.0V

–31dBv

(–30dBm)

–21dBv

50k

VCT

40kΩ

I

O

—

40k

147

VCC

VCT

300

147

300

VEE

V

CC

Playback input

VEE

Head select output of playback equalizer amplifier

—10—

VEE