ROHM BA7726AS, BA7726AFS Datasheet

1

Multimedia ICs

Analog compander with vocal fader
for KARAOKE

BA7726AS / BA7726AFS

The BA7726AS and BA7726AFS are analog companders for karaoke echo systems and have internal logarithmic
compression and expansion circuits, a stereo line mixer amplifier, vocal fader function, vocal detection function,
microphone ALC, microphone ON / OFF switch, and output switch. When used together with the BU9252 8-bit digital
delay, these ICs form a high-grade karaoke echo system with minimum components.

•

Features

1) Internal stereo line mixer amplifier, allowing selec­tion of through output, left output, or right output.

2) Internal vocal elimination function, suitable for vocal
faders and left and right output.

3) Echo level and loop ratio are DC-adjustable with the
internal electronic volume control (EVR).

4) Internal microphone ON / OFF switch.

5) Vocal detection.

6) Internal microphone ALC function.

7) Internal anti-popping circuit.

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Applications

Portable CD stereos with karaoke functions, VCRs, mini component stereo systems, LD players

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Absolute maximum ratings (Ta = 25°C)

Parameter Symbol Limits Unit

Power supply voltage V

CC 14 V

Power dissipation

BA7726AS

mW

BA7726AFS
Operating temperature Topr °C
Storage temperature Tstg °C

1250

∗

1

850

∗

2

Pd

– 10 ~ + 70
– 55 ~ + 125

∗

1 Reduced by 12.5mW for each increase in Ta of 1°C over 25°C.

∗

2 Reduced by 8.5mW for each increase in Ta of 1°C over 25°C.

•

Recommended operating conditions (Ta = 25°C)

Parameter Symbol Min. Typ. Max. Unit

Power supply voltage V

CC 4.5 9.0 12.0 V

2

Multimedia ICs BA7726AS / BA7726AFS

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Block diagram

123456789

32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17

10 11 12 13 14 15 16

OUTSW

VOCAL
FADER

SW

VOCAL

DET

ALC

VR

–

+

EXPAND

COMPRESS

–

+

–

+

VR

VR

BIAS

GND

VCC

LINE OUT R

LINE OUT L

L / VF / R CTRL

MUTE CTRL

LINE IN R

LINE IN L

VF LPF1

VF LPF2

LOOP GAIN CTRL

EXP DET

EXP DET CT

EXP BF IN

DLY BF OUT

L / ST / R CTRL

NO / VC CTRL

VO DET

VO DET LEVEL

ALC DET LEVEL

ALC DET

MIC AMP IN

MIC AMP NF

CMP DET

CMP DET CT

CMP OUT

CMP BF NF IN

CMP BF OUT

DLY BF NF IN

VF LPF3

ECHO LEVEL CTRL

3

Multimedia ICs BA7726AS / BA7726AFS

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Pin descriptions

Note: Pin type EF: emitter follower, P-P: push-pull, B: base

For pins marked with an asterisk (

∗

), refer to Input and output equivalent circuit.

Pin No. Pin name Function Voltage Pin type

2, 1 LINE OUT L / R Line output (L, R) 4.5V EF (P - P)

3 L / VF / R CTRL

Line output switching (LEFT / VOCAL FADER / RIGHT)

2.5V

4 MUTE CTRL Line mute control input —

6, 5 LINE IN L / R Line input (L, R) 4.5V 100kΩ

7 VF LPF1 Vocal fader mode LPF capacitor 4.5V 23.5kΩ
8 VF LPF2 Vocal fader mode LPF capacitor 4.5V 70.5kΩ
9 VF LPF3

Vocal fader mode LPF capacitor

4.5V EF (NPN), 15kΩ
10 GND Ground 0.0V —
11 ECHO LEVEL CTRL Microphone off (ground to 0.1Vcc) / echo level adjustment (0.2Vcc to Vcc) —
12 LOOP GAIN CTRL Loop attenuation ratio setting —
13 EXP DET Expand detection wave 4.5V 50kΩ

14 EXP DET CT

Expand attack / recovery time setting
Attack R = 5.6kΩ , recovery R = 85.6kΩ

—

15 EXP BF IN BF input 4.5V B (NPN)
16 DLY BF OUT LPF BF output (EXP) 4.5V EF (NPN)
17 DLY BF NF IN LPF BF negative feedback input (EXP) 4.5V B (NPN)
18 CMP BF OUT LPF BF output (CMP) 4.5V EF (P - P)
19 CMP BF NF IN LPF BF negative feedback input (CMP) 4.5V B (NPN)

20 CMP OUT Compression output 4.5V EF (NPN)
21 CMP DET CT

Compression attack / recover time setting
Attack R = 5.6kΩ, recovery R = 85.6kΩ

—

22 CMP DET Compression detection wave 4.5V 60kΩ
23 V

CC

V

CC

9.0V —
24 BIAS Bias and capacitor for ripple rejection 4.5V 23.5kΩ
25 MIC AMP NF Microphone amplifier negative feedback 4.5V 2kΩ
26 MIC AMP IN Microphone amplifier input 4.5V 100kΩ
27 ALC DET ALC attack / recovery time setting — 220Ω
28 ALC DET LEVEL ALC level setting — B (PNP)
29 VO DET LEVEL Microphone amplifier input detection level setting — B (PNP)
30 VO DET Microphone amplifier input detection attack / recover time setting — 1kΩ
31 NO / VC CTRL Line output switching (NORMAL / VOCAL CUT) —
32 L / ST / R CTRL Line output switching (LEFT / STEREO / RIGHT) 2.5V

—

—

All figures are designed values based on the measurement circuit in Fig. 1 (where Vcc = 9.0V), and are not guaranteed standards.

∗
∗

∗
∗

∗
∗

4

Multimedia ICs BA7726AS / BA7726AFS

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Input / output circuits

∗ All figures are designed values, and are not guaranteed standards.

VCC

3.3V

1.7V

3

VCC

85k

15k

11

39k

31

VCC

49.5k

33k

VCC

3.3V

1.7V

39k

0.6 × V

CC

0.8 × VCC

0.6 × VCC

0.8 × VCC

12

32

2.5V

150k

4

39k

39k 39k

39k 39k

39k

L / VF / R CTRL MUTE CTRL

LOOP GAIN CTRLECHO LEVEL CTRL

NO / VC CTRL L / ST / R CTRL

VCC