ROHM BH7775K Datasheet

1

Video ICs

VCR audio signal processing system

BH7775K

The BH7775K is an audio signal processing system IC that includes a peak-noise reduction (PNR) processor, an FM
modulator / demodulator circuit, an input / output switcher, an automatic FM detector circuit, an FM band-pass filter,
a normal-audio circuit, a regulator circuit, and automatic adjusting circuits (VCO and BPF).

•

Applications

VHS Video cassette recorders

•

Features

1) Operates off dual ± power supply which allows a
large reduction in the number of coupling capacitors
required. A built-in regulator makes it easy to con­struct a power supply system.

2) A built-in 2-wire serial control decoder circuit allows
serial control of the internal mode settings.

3) Automatic adjusting VCO and BPF circuits that use
the color signal subcarrier frequency (NTSC:

3.579545MHz and PAL: 4.433619MHz) ensure sta­ble adjustment that is not effected by stress when
the chip is mounted, or variations over time.

4) 4-input switcher (turner, BS, and line 1 and 2).
Output switch with built-in STEREO / LEFT / RIGHT
switching, Hi-Fi / MIX / NORMAL switching, and BS
monitor functions.

5) The PNR processor and FM modulation / demodula­tion circuit provide reverse characteristics at record-

ing and playback. Also, carrier frequency adjustment
and FM de-emphasis / playback level adjustment
have been combined.

6) Built-in FM band-pass filter connects directly to the
playback amplifier and excels at attenuation of the
other channel. The FM recording output circuit has a
high-performance high-frequency cutoff filter that
produces a sine wave output.

7) Switching noise is reduced by a slope-control type
differential compensation circuit.

8) Built-in envelope detector circuit and noise-detecting
automatic FM detector circuit.

9) Built-in normal-audio signal processing circuit that
allows SP / LP / EP equalizer switching. Control ter­minal provided for use with the BA7755AF high-volt­age head switcher.

2

Video ICs BH7775K

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Absolute maximum ratings (Ta = 25°C)

Parameter Symbol Limits Unit

V

CC

23, 55 pin · · · · · · · · · · 6.0

V

V

EE

59 pin · · · · · · · · · · · · – 6.0

V

V

IN 7, 8, 22 pin · · · · · · · · · 6.5 V

V

IN V

Pd mW
Topr – 10 ~ + 70 °C
Tstg – 55 ~ + 125 °C

Pin other than above

· · · · 6.0

Applied voltage

Power dissipation
Operating temperature
Storage temperature

∗

When IC is stand alone, reduced by 8.0mW for each increase in Ta of 1°C over 25°C. When mounted on a

90mm × 50mm, t = 1.6mm glass epoxy board, Pd = 1.3W (reduced by 13.0mW for each increase in Ta of

1°C over 25°C).

䊊

Not designed for rediation resistance.

800

∗

•

Recommended operating conditions (Ta = 25°C)

Power supply voltage
Power supply voltage

∗

The built-in regulator in this IC outputs + 5.0V from pin 55, and - 5.0V from pin 59. The supply voltage range

given above is the voltage to be applied to UNREG V

CC and UNREG VEE pins in the measurement circuit to

obtain regulator output. Therefore, the upper limit of the voltage range is set by the externally connected
transistor that forms the regulator circuit, and not by the IC itself. Note, also, that the lower limit will change
depending on the value of the resistor connected between the collector and base of the transistor.

Parameter

UNREG-V

CC

V

+ 7.0 ~

∗

UNREG-VEE V

+ 7.0 ~

∗

Symbol Range Unit

3

Video ICs BH7775K

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Block diagram

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

DC FB L

VCO f

0 ADJ L

DAC BF OUT L

GNML

FM PB IN

MUTE CTRL

VCB

BPF f

0 ADJ

FM ALC

RHS CTRL

AUDIO HEAD SW

PULSE IN

FM REC OUT

GNMR

DAC BF OUT R

VCO f0 ADJ R

DC FB R

NA REC OUT

HEAD EQ

NA HEAD IN

GNN

NA PB NFB

PB EQ

NA PB OUT

NA PB IN

NA ALC

NA FB

Hi-Fi IN R

Hi-Fi OUT R

NR TC R

WTNG1 R

WTNG2 R

NR EMPH R

BS R IN

BS L IN

TUNER R IN

TUNER L IN

TUNER M IN

GNDD

DATA

CLOCK

ENVE OUT / ADJ FLAG

/ Hi-Fi DET

FSC IN

Hi-Fi IN L

Hi-Fi OUT L

NR TC L

WTNG1 L

WTNG2 L

NR EMPH L

VREFP

LINE2 L IN

LINE2 R IN

LINE1 L IN

LINE1 R IN

V

EE

ERM

GND

ERP

Vcc

LINE OUT L

LINE OUT R

MIX OUT

MIX ALC

NA REC FB

REC EQ

64

63

62

61

60

59

58

57

56

55

54

53

52

51

50

49

12345678910111213141516

48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33

RECAMP
REC EQ

EQ

EQ

PB

MIX

AMP

AMP

OUTPUT
SWITCH

SW

ATT

LINE
AMP

LINE
AMP

REC

INPUT

SWITCH

DATA

DECODER

PNR

MODEM

ENVE
LOPE

FM BPF

D.O.

COM.

Hi-Fi
DET

MODEM

PNR

ALC

4

Video ICs BH7775K

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Pin descriptions

I / O circuitPin voltagePin name Function

3kΩ (2.5V Min.)

BS input (L and R).
TUNER input (L, R, and M).
Serial control GND.
Serial control data input.
Serial control clock input.
FM input Lch signal component envelope output.

Hi

-Fi DET output for FM input. ADJ FLAG output for ADJ.

fsc input terminal for VCO and BPF adjustment.
Hi

-Fi input for output switcher.

PNR audio output.
PNR attack and recovery time setting. Attack

R: 530

Ω, recovery R: 6.5kΩ.

Waiting characteristic low-frequency time constant setting
Waiting characteristic high-frequency time constant setting
NR emphasis time constant setting.

(external C = 0.01

µF)

PNR operating reference potential.
VCO control current setting terminal.
VCO control DAC voltage output terminal .

PNR, MODEM and BPF GND. L and R unconnected.

FM BPF center frequency adjustment.
FM ALC time constant setting.

Note) I / O circuit; EF: emitter follower, P-P: push pull, B: base, and C: collector.

All numerical values are standardized values.

Playback FM input. 660mVP-P Typ.
No input coupling capacitor (GND to V

CC).

Line output mute control input.
MODEM and BPF V

CC.

High-voltage head switch (BA7755) control terminal.
Audio head switching pulse input.

EE: recording FM output. Sine wave output.
PB: BPF output monitor terminal.

Pin No.

2, 1 BS IN L, R 0.0V 69.8kΩ

4, 3, 5 TUNER IN L, R, M 0.0V 47.0kΩ

6 GNDD 0.0V —
7 DATA IN — B (PNP)
8 CLOCK IN — B (PNP)

10 FSC IN 0.0V 200kΩ
11, 38 Hi-Fi IN L, R 0.0V 47kΩ
12, 37 Hi-Fi OUT L, R 0.0V EF: (P-P)

14, 35 WTNG1 L, R 0.0V 10kΩ
15, 34 WTNG2 L, R 0.0V 1.1kΩ

17, 32 DC FB L, R 0.0V 11.5kΩ
18, 31 VCO f

0 ADJ L, R 2.5V EF (NPN)

19, 30 VCO DAC BF OUT L, R 1.4V EF (NPN)

22 MUTE CTRL —

23 VCB 5.0V —

26 RHS CTRL — C (NPN)

24 BPF f

0 ADJ 1.9V EF (NPN) ~ 200Ω

27 AHSWP IN — B (PNP)

28 FM REC OUT

EE: 3.3V
PB: 3.3V

EF (NPN) ~ 200Ω

9

ENVE OUT / Hi-Fi DET

/ ADJ FLAG

EE: 0.8V
PB: 1.0V

EE: 50kΩ

PB, ADJ: EF (NPN)

13, 36 NR TC L, R – 5.0V —

16, 33 NR EMPH L, R 0.0V —

20, 29 GND (GNM) L, R 0.0V —

21 FM PB IN 0.0V 50kΩ

25 FM ALC 0.0V EF (NPN) ~ 2.5kΩ

Pin function - 1 / 2

5

Video ICs BH7775K

∗

I / O circuit; EF: emitter follower, P-P: push pull, B: base, and C: collector.

All numerical values are standardized values.

Pin name Function Pin voltage

Normal line amplifier feedback.
Normal line amplifier ALC time constant setting

(attack and recovery time).
Normal line amplifier playback input.
Normal PB amplifier output.
Normal PB amplifier equalizer switch.
Normal PB amplifier feedback.
Normal audio GND.

Normal audio playback input.
Head resonance equalizer switch terminal.

Normal REC amplifier output.
Recording equalizer setting resistor terminal.
Normal REC amplifier feedback terminal.
ALC time constant setting for mixer amplifier

(attack and recovery time).
Mixer amplifier output for RF converter.
Line output
V

CC regulator.

V

CC regulator error output.

Output switch, regulator GND.
V

EE regulator error output.

VEE regulator
LINE 1 input (L and R).
LINE 2 input (L and R).

V

CC / 2 reference voltage. With power on detect

and precharge function.

I / O circuit

Pin No.

39 NA FB 0.0V 800Ω

41 NA PB IN 0.0V 105.2kΩ

42 NA PB OUT 0.0V EF (P-P) ~ 50Ω

43 PB EQ 0.0V OPEN / 25Ω

44 NA PB NFB 0.0V B (NPN)

45 GNN 0.0V —

47 HEAD EQ 0.0V 300kΩ / 29Ω

48 NA REC OUT 0.0V EF: (P-P)

49 REC EQ 0.0V 1kΩ

50 NA REC FB 0.0V B (NPN)

52 MIX OUT 0.0V EF (NPN)
54, 53 LINE OUT L, R 0.0V 330Ω

55 V

CC 5.0V —

56 ERP 5.0V C (NPN)

57 GND 0.0V —

58 ERM – 5.0V

– 5.0V

C (PNP)

59 V

EE —

61, 60 LINE1 IN L, R 0.0V 90.2kΩ
63, 61 LINE2 IN L, R 0.0V 90.2kΩ

64 VREFP

2.5V

10kΩ

40

NA ALC 0.0V EF (NPN) ~ 500Ω

46

NA HEAD IN 0.0V

REC: B (NPN)
REC: EF (P-P)

51

MIX ALC – 5.0V EF (NPN) ~ 500Ω

Pin function - 2 / 2

6

Video ICs BH7775K

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Input / Output circuits

Equivalent circuits for the control and input / output circuits - (1)

4 61

47k

– 2.0V

2.0V

[3, 5pin]

Vcc

V

EE

GND

Vcc

V

EE

GND

[60, 63,

62pin]

60.2k

30k

2.0V

– 2.0V

2

54

Vcc

V

EE

GND

Vcc

V

EE

GND

[1pin]

22.8k

47k

2.0V

– 2.0V

330

10.13k

25k

26k

30k

50

50

[53pin]

28

52

Vcc

V

EE

GND

Vcc

V

EE

GND

200

200

5p

8k

5k

200

200

47k

TUNER L, R, M (4, 3, 5pin)

BS L, R (2, 1pin)

MIX OUT (52pin)

LINE1 L / R, LINE2 L / R (61, 60, 63, 62pin)

LINE OUT (54, 53pin)

FM REC OUT (28pin)