Sony CXA1878Q Datasheet

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

Description

The CXA1878Q is a bipolar IC with a built-in Dolby B-C type noise reduction system (NR), Dolby S type select switch, recording/playback equalizer, electronic volume, and bias control circuit.

Use of this IC in combination with two CXA1417S/Q completes a Dolby B-C-S type NR stereo system.

Features

• Dolby B-C type NR

• Built-in filter required for recording/playback equalizer

amplifiers

• Recording mute function

(requiring only an external time constant circuit to

implement soft mute)

• Fade in/out DC controllable

• NORM/CrO2/METAL tape mode switching function

• NORM/HIGH tape speed switching function

• DC controllable for recording level calibration

(approximately ±6dB variable)

• DC controllable for high frequency equalizer

amplifier gain (approximately ±4dB variable)

• Playback deck A/B select switch

• Recording volume control

• Bias control circuit

• Meter circuit

CXA1878Q

64 pin QFP (Plastic)

Structure

Bipolar silicon monolithic IC

Absolute Maximum Ratings

• Supply voltage VCC 17 V

• Operating temperature Topr –20 to +75 °C

• Storage temperature Tstg –65 to +150 °C

• Allowable power dissipation PD 1020 mW

Operating Conditions

Supply voltage (VCC • VEE) ±6.5 to 8.0 V

Applications

Recording/playback equalizer amplifier for stereo

analog cassette decks

(Applicable to ALPS ELECTRIC CO., LTD.

HADKH55 series heads)

∗ 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.

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 –

E95933A5Z-PK

GP CAL 32

VEEDGND 31

30

REC BAL

REC VOL

28

29

METER2

METER1

27

26

B EQ

DECK A/B

(A/B)

24

25

2/METAL)

(NORM/CrO

A EQ

(120µ/70µ)

23

CC

DV 22

VCC 21

MODE SW

(REC/PB)

20

CXA1878Q

REC CAL

33

(OFF/B/C) NR SW

34

(S/BC/CAL) S SW

35

AMS OUT

36

AMS TC

37

AMS FB

38

AMS

BS FB

39

MT C2

40

CAL IN

4142

REC MUTE

REC OUT2

43

NR RECOUT2

44

REC IN2

S IN2

NR OUT2

NR TCL2

NR TCH2

LINE OUT2

NR RECIN2

REC-EQ

45

46

47

48

49

50

51

D GND

VOLUME

52

53

NR

54

PB

GND

PASS

MUTE

LINE

CONT

VOLUME

S

DOLBY

REC

OFF

DECK

55

B/C

CAL

B-C NR

METER

ON

CAL

OFF

MOA

PB

CAL

ON

PB EQ

B

56

METER2

METER1

CXA1878Q

GND

MUTE

ON

A

57

58

MUTE

GND

ON

A

GND

59

CAL

OFF

MOA

PB

ON

PB EQ

S

B/C

CAL

DOLBY

B-C NR

METER

ON

REC

CAL

B

DECK

60

OFF

PASS

MUTE

LINE

61

PB

GND

NR

62

VOLUME

63

METAL NORM CrO2

REC-EQ

64

(NS/HS)

19

18

17

16

15

14

13

12

VEE

11

10

9

8

7

6

5

4

3

2

1

SPEED

BIAS N

BIAS C

BIAS M

MT C1

IREF

S IN1

(ON/MUTE)

METER SW

PASS SW

(OFF/AMS/BS)

AMS SW

NR IREF

REC OUT1

NR RECOUT1

REC IN1

NR OUT1

NR TCL1

NR TCH1

LINE OUT1

NR RECIN1

(NR/MUTE/PASS)

VOL IN2

VOL OUT2

PB OUT2

NR PBIN2

Block Diagram and Pin Configuration

PB INB2

GND

PB INA2

– 2 –

PB INA1

PB INB1

PB OUT1

NR PBIN1

VOL IN1

VOL OUT1

CXA1878Q

Pin Description

Pin No.

1

51

2

50

Symbol

NR RECIN1 NR RECIN2

LINE OUT1 LINE OUT2

Typical pin voltage

DC AC

0.0V

–26dBv

–4dBv

(Ta = 25°C, VCC = 7.0V, VEE = –7.0V, DVCC = 5.0V)

I/O Z (in) Equivalent circuit Description

GND

40k

51

1

300

2

50

300

I

40kΩ

O

—

1.5k

Recording equalizer amplifier input

3.4k

Line output

3

49

4

48

NR TCH1 NR TCH2

NR TCL1 NR TCL2

VEE

+0.4V

VEE

+0.4V

—

3

49

48

330k

13k

36k

13.5k

4

480k

Time constant for the HLS

Time constant for the LLS

– 3 –

CXA1878Q

No.

5

47

6

46

Symbol

NR OUT1 NR OUT2

S IN1 S IN2

Typical pin voltage

DC AC

0.0V

–6dBm

(–7dBv)

–6dBm

(–7dBv)

I/O Z (in) Equivalent circuit Description

192

47

5

192

20k

6

46

40k

O

—

I

40kΩ

12k

1.5k

Dolby S type NR output

GND

Dolby S type NR input

7

REC IN1

45

REC IN2

8

NR RECOUT1

44

NR RECOUT2

0.0V

–24dBv

–6dBm

(–7dBv)

GND

9.5k

Recording equalizer amplifier input

Dolby NR recording signal output

44

8

45

7

50k

GND

211

22.5k

1.5k

I

50kΩ

O

—

– 4 –

GND

CXA1878Q

No.

9

43

10

Symbol

REC OUT1 REC OUT2

IREF

Typical pin voltage

DC AC

VEE

–3dBv

—

0.0V

+1.2V

I/O Z (in) Equivalent circuit Description

200

43

9

200

O

—

50k

Recording equalizer amplifier output

Reference current setting for built-in recording/playback equalizer amplifier

∗

The reference current

—

192

10

can be set by connecting a resistor

6k

between this pin and VEE.

11

12 40

NR IREF

MT C1 MT C2

VEE

+1.2V

0.0V

—

O

—

12 40

11

14k

8k

40k

Reference current setting for built-in Dolby NR

∗

The reference current can be set by connecting a resistor between this pin and VEE.

300

DC cut capacitance

300

– 5 –

CXA1878Q

Pin No.

13 14 15

16

Symbol

BIAS M BIAS C BIAS N

AMS SW

Typical pin voltage

DC AC

—

2.5V

when

—

open

I/O Z (in) Equivalent circuit Description

O

—

13 14 15

100k

Recording bias control voltage output

AMS mode control

∗

Mode select switch for AMS/BS amplifier High: BS mode Medium: AMS mode

50k

I

—

16

5k

Low: AMS/BS OFF mode [BS mode = Music signal interval detection during playback]

24k

DGND

[AMS mode = Music signal detection during FF/REW]

17

18

PASS SW

METER SW

2.5V when open

—

5k

I

—

50k

17

5k

DGND

H : PASS M : MUTE L : NR ON

Meter mode control

PASS mode control

∗

10k

—

I

18

Meter amplifier output ON/OFF select switch High: Meter output

OFF (mute)

DGND

Low : Meter output ON

– 6 –

CXA1878Q

Pin No.

19

20

Symbol

SPEED

MODE SW

Typical pin voltage

DC AC

—

I/O Z (in) Equivalent circuit Description

Tape speed selection

10k

—

19

10k

I

∗

Normal speed/ double speed selection High: Double speed Low : Normal speed

DGND

Recording/playback

2k206k

I

—

mode control

∗

Recording/playback mode selection High: Recording mode Low : Playback mode

2122VCC

DVCC

23

A EQ

24

B EQ

7.0V

5.0V——

2.5V when open

—

I

—

I

—

Positive power supply Reference power

supply for mode control

Deck A playback equalizer amplifier control

∗

23

I

—

10k

120µs/70µs selection High: 70µs Low : 120µs (Built-in equalizer

DGND

amplifier flat)

Control of deck B playback equalizer amplifier mode, recording equalizer

I

—

24

10k

amplifier mode, and recording bias mode

∗

NORM/CrO2/METAL selection High : METAL

DGND

Medium : CrO2 Low : NORM

– 7 –

CXA1878Q

Pin No.

25

26 27

Symbol

DECK A/B

METER1 METER2

Typical pin voltage

DC AC

—

1.6V

—

–1.1dBv

I/O Z (in) Equivalent circuit Description

Playback deck A/B select control

∗

I

—

10k

25

Playback equalizer amplifier input selection High: PB INB

DGND

60k

O

—

26 27

10k

Low : PB INA

Level meter amplifier output

28

29

30

REC VOL

REC BAL

DGND

—

2.5V when open

0.0V

—

I

100kΩ

29

28

70k 30k

DV

60k

40k

CC/2

GND

8k

21k

8k

Recording volume level control

High: Output signal

level increased

Low : Output signal

level reduced

Recording volume balance control

High: Only VOL OUT2

output level reduced

Low : Only VOL OUT1

output level reduced

∗

Neither VOL OUT1 nor 2 output levels are attenuated at the control voltage of 2.5V.

Connect to GND.

– 8 –

CXA1878Q

No.

31

32

33

Symbol

VEE

GP CAL

REC CAL

Typical pin voltage

DC AC

–7.0V

2.5V

when

—

open

2.5V

when

—

open

I/O Z (in) Equivalent circuit Description

Negative power supply Recording equalizer

amplifier high frequency calibration

∗

Controlled with DC voltages of 0 to 5V. High: High frequency

54k

I

54kΩ

32

level gain increased

Low : High frequency

level gain reduced

∗

Leave this pin open when not using the high frequency calibration function.

Recording equalizer amplifier calibration

∗

Controlled with DC voltages of 0 to 5V. High: Recording level

54k

I

54kΩ

33

gain increased

Low : Recording level

gain reduced

∗

Leave this pin open when not using the recording calibration function.

34

35

NR SW

S SW

2.5V

when open

2.5V

when open

—

2k 6k

I

50kΩ

34

50k

DV

CC/2

NR control

High: C type Medium: B type Low: NR OFF

Dolby S type selection

2k 6k

I

50kΩ

35

50k

∗

Select the calibration mode with this pin. High: CALIBRATION Medium: B-C type Low: S type

CC/2

DV

– 9 –

CXA1878Q

No.

36

37

Symbol

AMS OUT

AMS TC

Typical pin voltage

DC AC

0.0V

—

I/O Z (in) Equivalent circuit Description

37

36

1k

DGND

10k

10k 10k

40k

AMS amplifier output

Time constant for the AMS

O

—

38

39

AMS FB

BS FB

0.0V

—

39

38

2p

100k

2p

100k

Feedback during AMS mode

Feedback during BS mode

– 10 –

CXA1878Q

Pin No.

41

42

Symbol

CAL IN

REC MUTE

Typical pin voltage

DC AC

—

–26dBv

—

0.0V

I/O Z (in) Equivalent circuit Description

GND

10k

I

10kΩ

41

1.5k

Calibration signal input

Recording mute ON/OFF selection

∗

30k

The recording mute is controlled with DC voltages of 0 to 5V.

I

—

42

GND

High: Recording mute OFF Low : Recording mute ON

∗

Soft mute and fader functions can be set by changing the time constant of the external time constant circuit.

64 52

63 53

VOL OUT1 VOL OUT2

VOL IN1 VOL IN2

0.0V

–10dBv

500

O

I

50kΩ

64 52

500

63 53

5p

6.5k

Recording volume amplifier output

Recording volume amplifier input

– 11 –