ROHM BH7800K Datasheet

1

Video ICs

Single chip Hi-Fi audio signal
processor

BH7800K

The BH7800K incorporates the functions for a VHS audio signal processing system on a single chip. The circuits on
the chip are a peak-noise reduction processor (PNR), an FM modulator / demodulator circuit, an I / O switcher, an
automatic FM detector circuit, an FM bandpass filter, and a regulator circuit.

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 two-line SSB (Synchronized Serial Bus) control
decoder circuit is provided, allowing the various IC
modes to be set using serial control.

3) A four line input switcher is included (tuner, BS, and
line 1 / 2). The output switcher can switch between
STEREO, LEFT, and RIGHT, and Hi-Fi, MIX, and
NORMAL, and a BS MONITOR function is also pro­vided.

4) The PNR processor and FM modulator / demodula­tor circuit have reversed characteristics at recording
and playback. In addition, the adjustment for carrier
frequency and FM deviation / playback level are
common.

5) The built-in bandpass filter excels at attenuation of
other channels, and can be directly coupled to the
playback amplifier. The FM recording output block
has a high-performance low-pass filter to produce
sine wave output.

6) Slope-control-type FM-switching-noise compensa­tion circuit.

7) Envelope detector circuit and noise-detector-type
automatic FM detector circuit.

8) VCO that uses the color signal sub-carrier frequency
f

SC (NTSC: 3.59545MHz, PAL: 4.433619MHz) and

auto-adjusting BPF circuit ensure stable adjustment
with no fluctuation due to mounting stress or time.

•

Absolute maximum ratings (Ta = 25°)

Parameter

Applied voltage

Storage temperature

V

CC

VEE

VIN

Tstg

18, 36pin ··························· 6.0
39pin ······························ – 6.0
5, 6, 32pin ························

···

6.5

Pins other than the above 6.0

– 55 ~ + 125

V

Symbol Limits Unit

V
V

VIN V

Power dissipation Pd

850

∗

mW

Operating temperature Topr – 10 ~ + 70 °C

°C

∗

Reduced by 8.5mW for each increase in Ta of 1°C over 25°C when mounted on a 70mm × 70mm, t = 1.6mm glass epoxy board.

•

Features

•

Applications

VCRs

2

Video ICs BH7800K

•

Block diagram

33 32 31 30 29 28 27 26 25 24 23

1

INPUT

SWITCH

MIX

AMP

PNR

ENVE

LOPE
Hi-Fi

DET

MODEM

ALC

DATA

DECODER

MODEM

FM

BPF

VCO BPF

AUTO

ADJUST

D.O
COM.

FM

OUT

SW

2 3

REG

4 5 6 7 8 9 10 11

TUNER R IN

TUNER L IN

TUNER M IN

HiFi ALC

SCL

SDA

GNDD

FSC IN

NR TC L

WTNG L

NR EMPH L

LINE2 R IN

MUTE CTRL

NORMAL OUT

LINE L OUT

LINE R OUT

MIX OUT

MIX ALC

NORMAL IN

NR TC R

WTNG R

NR EMPH R

DC FB R

FM REC OUT

AUDIO HEAD SW
PULSE IN

FM ALC

VCCM

VCO FO ADJ

BPF ADJ

GNDM

ENVE OUT / ADJ FLAG

/ Hi-Fi DET

FM PB IN

DC FB L

LINE2 L IN

VREFP

V

CC

ERP

GND

V

EE

LINE1 R IN

LINE1 L IN

ERM

BS R IN

BS L IN

34

35

36

37

38

39

40

41

42

43

44

22

21

20

18

17

16

15

14

13

12

LINE

AMP

AMP

LINE

OUTPUT
SWITCH

PNR

19

3

Video ICs BH7800K

•

Pin descriptions

Pin No. Pin name FormatVoltageFunction

2, 1, 3 TUNER IN L, R, M 150kΩ0.0VTuner input (L, R, M)

4 Hi-Fi ALC EF (NPN) ~ 200Ω0.0VALC time constant setting for Hi-Fi audio
5 SCL B (PNP)—CLOCK input for SSB control
6 SDA B (PNP)—

—

DATA input for SSB bus control
7 GNDD GND for serial control
8 FSC IN 200kΩ0.0V

9, 25 NR TC L, R —

—
—

—

– 5.0V

fSC input for VCO and BPF adjustment

12, 22 DC FB L, R 23kΩ0.0VPNR operating reference potential point

15 GNDM —0.0VGND for PNR, MODEM and BPF
16 BPF f0 ADJ EF (NPN) ~ 200Ω1.9VCenter frequency adjustment for FM BPF
17 VCO f0 ADJ EF (NPN)2.5VVCO control current setting
18 VCCM —5.0VVCC for MODEM and BPF
19 FM ALC EF (NPN) ~ 2.5kΩ0.0VFM ALC time constant setting
20 AHSWP IN B (PNP)—Audio head switching pulse input

26 NORMAL IN 100kΩ0.0VNormal input

28 MIX OUT EF (NPN)0.0VMixer amplifier output for RF converter

30, 29 LINE L, R OUT 330Ω0.0VLine output

31 NORMAL OUT EF (P-P)0.0VNormal output
32 MUTE CTRL 3kΩ ( > 2.5V)—Line output mute control input

34, 33 LINE2 L, R IN 150kΩ0.0VLine2 input (L, R)

36 VCC —5.0VVCC regulator
37 ERP C (NPN)5.0VVCC regulator error output
38 GND —0.0VI / O switch GND
39 VEE —– 5.0VVEE regulator

41, 40 LINE1 IN L, R 150kΩ0.0VLINE1 input (L, R)

42 ERM C (PNP)– 5.0VVEE regulator error output

44, 43 BS IN L, R 150kΩ0.0VBS input (L, R)

PNR attack and recovery time setting

Attack R: 530Ω, Recovery R: 6.5kΩ

10, 24 WTNG L, R 0.0VWaiting characteristic, treble time constant (external C = 0.0047µF)
11, 23 NR EMPH L, R 0.0V

NR emphasis time constant setting

(External C = 0.0047µF)

13 FM PB IN 100kΩ0.0V

Playback FM input 1320mV

P-P Typ.

Input coupling capacitor (GND ~ V

CC)

21 FM REC OUT EF (NPN) ~ 200Ω3.3V

EE: recording FM output , sine wave output

PB: FM BPF output monitor

27 MIX ALC EF (NPN) ~ 500Ω– 5.0V

ALC time constant setting for mixer amplifier

Attack and recovery time setting

35 VREFP 10kΩ2.5V

V

CC / 2 reference voltage (power on detect and pre-charge functions)

14 / ADJ FLAG

/ Hi-Fi DET

ENVE OUT

EE: 50kΩEE: 0.8V

PB, ADJ: EF (NPN)PB: 1.0V

FM Lch signal component envelope output

/ Hi-Fi DET output / ADJ FLAG output for ADJ

Note: EF: emitter follower, P-P: push pull, B: base, and C: collector.
All numerical values are standardized values.

4

Video ICs BH7800K

•

Input / output circuits

TUNER L / R / M IN (2, 1, 3pin) BS L / R IN (44, 43pin) LINE1 L / R IN (41, 40pin) LINE2 L / R IN (34, 33pin)

LINE L / R OUT (30, 29pin) MIX OUT (28pin)

FM REC OUT (21pin) FM PB IN (13pin)

VCC

VEE

GND

1

3k

(2, 3, 33, 34, 40,

41, 43, 44pin)

– 2.0V

2.0V

150k

VCC

VEE

GND

25k 330

30

(29pin)

11.56k

26k

30k

50

50

VCC

VEE

GND

200

21

8k

200

VCC

VEE

GND

200

5k

47k

200

28

3p

VCC

VEE

GND

2k25k 25k

13

12.5k

3.5V

100k

20p

PB