Datasheet BA7726AS, BA7726AFS Datasheet (ROHM)

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.

•

Applications

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

•

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

•

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

•

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

•

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

5

Multimedia ICs BA7726AS / BA7726AFS

•

Electrical characteristics (unless otherwise noted, Ta = 25°C, Vcc = 9.0V)

Parameter Symbol Min. Typ. Max. Unit Conditions

Supply current I

CC 5.5 8.4 12.7 mA No input

Line through output level V

OLL – 9.0 – 8.0 – 7.0 dBV VIN = – 20.0dBV

Line through output distortion THD

LL — 0.026 0.2 %

Line through max. output level V

OMLL + 7.8 + 10.0 — dBV

Line through noise level V

ONLL — – 100 – 85 dBV

MIC OFF (V

ECHO = 0.1 × VCC)

Interchannel crosstalk CT

LL — – 85 — dBV

MIC OFF (V

ECHO = 0.1 × VCC)

Mute level MT — – 100 – 85 dBV

MUTE (V

MUTE = H)

MIC OFF (V

ECHO = 0.1 × VCC)

Through mode output level V

OLLV – 1.0 0.0 + 1.0 dBV VIN = – 12dBV

V

OLL1 – 1.0 0.0 + 1.0 dB

V

OLL2 —–35–28 dB

Microphone through output level

VOML – 9.9 – 8.4 – 6.9 dBV VIN = – 38dBV

Microphone through
equivalent input noise

V

ONML — – 117 – 102 dBV

Microphone input crosstalk CT

ML — – 92 – 77 dBV

MIC OFF (V

ECHO = 0.1 × VCC)

ALC level V

OAML + 5.1 + 6.6 + 8.1 dBV V28 = 2.9V

Compress output level V

OMC – 5.5 – 3.5 – 1.5 dBV VIN = – 38dBV

Compress characteristics CMP — + 5.2 — dB

V

IN = – 43dBV → – 33dBV

Output level differential

Expand output level V

ODL – 9.4 – 7.4 — dBV VIN = – 4dBV

Expand characteristics EXP — + 19.4 — dB
Echo EVR attenuation ratio — – 50 – 40 dB

Loop output level V

ODC – 4.4 – 2.4 — dBV VIN = – 4dBV

Loop EVR attenuation ratio — – 29 — dB

〈LINE THROUGH〉 INPUT : LINE IN, OUTPUT : LINE OUT

〈VOCAL CUT MODE〉 INPUT : LINE IN, OUTPUT : LINE OUT

〈MIC THROUGH〉 INPUT : MIC AMP IN, OUTPUT : LINE OUT

〈COMPRESS〉 INPUT : MIC AMP IN, OUTPUT : CMP BF OUT

〈EXPAND〉 INPUT : DLY BF IN, OUTPUT : LINE OUT

〈Loop〉 INPUT : DLY BF IN, OUTPUT : CMP BF OUT

∆V

ODC

∆VODL

LOOP GAIN = Min. (VLOOP = 0.2 × VCC)

V

IN = – 4dBV and when VIN = Vodc

ECHO LEVEL = Min. (V

ECHO = 0.2 × VCC)

V

IN = – 4dBV and when VIN = Vodl

V

IN = – 9dBV → + 1dBV, Output level differential

(V

LSTR = H, VLVFR = OPEN, VNOVC = OPEN)

V

IN = – 12dBV (dual ch.in.),VOCAL FADER

(V

LSTR = H, VLVFR = OPEN, VNOVC = OPEN)

V

IN = – 12dBV (single ch. in.),VOCAL FADER

MIC OFF (V

ECHO = 0.1 × VCC)

Vocal suppression ratio 1

Vocal suppression ratio 2

∗

1 Unless otherwise noted, mode settings are as follows.

∗

2 All parameters conform to the Measurement circuit diagram.

MUTE (V

MUTE = GND), STEREO (VNOVC = GND, VLSTR = OPEN, VLVFR = OPEN)

ECHO LEVEL = Max. (V

ECHO = VCC), LOOP GAIN = Max. (VLOOP = VCC)

Signal frequency : 1kHz,

∗

1 : B.W. = 0.4 ~ 30kHz, ∗2 : DIN AUDIO

VIN = – 20.0dBV

∗

1

No input, Rg = 1kΩ

∗

2

V

IN – 12dBV, Rg = 1kΩ

∗

2

V

IN = – 12dBV, Rg = 1kΩ

∗

2

THD = 1%

∗

1

Rg = 1kΩ

∗

2

V

IN = – 30dBV

∗

2

6

Multimedia ICs BA7726AS / BA7726AFS

Parameter Symbol Min. Typ. Max. Unit Conditions

[ Control holding voltage ]

〈MUTE CTRL (4pin)〉

Mute holding voltage (4pin) VMUTE – L GND — 0.5 V

V

MUTE – H 4.5 — 5.0 V

Normal mode holding voltage V

NOVC – L GND — 0.3 × VCC V

V

NOVC – H 0.5 × VCC —VCC V

Left mode holding voltage V

LSTR – L GND — 0.5 V

Stereo mode holding voltage V

LSTR – M 2.2 — 2.8 V

Right mode holding voltage V

LSTR – H 4.5 — 5.0 V

Left mode holding voltage V

LVFR – L GND — 0.5 V

V

LVFR – M 2.2 — 2.8 V

Right mode holding voltage V

LVFR – H 4.5 — 5.0 V

V

ECHO – L GND — 0.1 × VCC V

V

ECHO – H 0.2 × VCC —VCC V

〈NO / VC CTRL (31pin)〉

VOCAL CUT mode holding voltage

〈L / ST / R CTRL (32pin)〉

〈

L / VF / R CTRL (3pin)〉

VOCAL FADER mode holding voltage

〈ECHO LEVEL CTRL (11pin)〉

MIC OFF holding voltage
MIC ON holding voltage

Mute holding voltage (4pin)

7

Multimedia ICs BA7726AS / BA7726AFS

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

–

+

–
+

VLVFR

VMUTE

VECHO

VLSTR

VNOVC

V

CC 9V

2.2µ
4700p

10k

+

2.2µ
4700p

+

10k

1k 1k

0.1µ

0.1µ

0.015µ

0.068µ

0.1µ+0.47µ

100k

33µ

1k

+

6.8k

3.3k

+

2.2M

47µ

1k

0.1µ

+1µ+

22µ

A

+

0.1µ

0.47µ

+

100µ

5600p

18k

47k

3900p

18k

39k
220p

47k

3900p

5600p

18k

1µ

1µ

+

+

18k

10k

1k

220p

39k

COMPRESS

EXPAND

VLOOP

8.2k

VR

VR

VR

LINE OUT R

LINE OUT L

LINE IN R

LINE IN L

MIC AMP IN

CMP BF OUT

DLY BF IN

–

+

Fig. 1

•

Measurement circuit

8

Multimedia ICs BA7726AS / BA7726AFS

•

Circuit operation

(1) MUTE CTRL (pin 4)

• Controls line muting.

2) L / ST / R CTRL (pin 32)

• Controls LINE OUT output in the NORMAL mode.

(2) OUTPUT CTRL (pins 3, 31, 32)

• LINE OUT output is controlled with pins 3, 31 and 32.
(Microphone mixing is controlled with pin 11.)

1) NO / VC CTRL (pin 31)

• Used to select the NORMAL and VOCAL CUT modes.

LH

MUTE MUTE

VMUTE (4pin)

LH

NORMAL

NORMAL : Normal output mode. Controlled by pin 32.
VOCAL CUT : Used to erase or attenuate vocals in

multiplexed karaoke recordings and
normal stereo music recordings.
Controlled by pin3.

VOCAL CUT

V

NOVC (31pin)

VLSTR (32pin)

L M (OPEN) H

LEFT STEREO RIGHT

RIGHT : LINE IN R input is output to LINE OUT L / R.

STEREO : LINE IN L / R input is output to LINE OUT L / R without modification

LEFT : LINE IN L input is output to LINE OUT L / R.

3) L / VF / R CTRL (pin 3)

• Controls LINE OUT output in the VOCAL CUT mode.

RIGHT : For recordings in which the right channel is karaoke

and the left channel is for vocals (with karaoke).

LEFT : For recordings in which the left channel is karaoke

and the right channel is for vocals (with karaoke).

VLVFR (3pin)

L M (OPEN) H

LEFT RIGHT

VOCAL FADER : Attenuates the vocals from normal stereo recordings.

VOCAL FADER

∗ When Vnovc = L, VLVFR = DON 'T CARE

When Vnovc = H, V

LSTR = DON 'T CARE

(3) ECHO LEVEL CTRL and MIC ON / OFF SW (pin 11)

• Between Vcc and 0.2 × Vcc: Controls echo signal
mixing ratio

Between Vcc and GND : Turns microphone input
sound (pin 26) to LINE OUT on and off

V

CC

~ 0.2 × V

CC

0.1 × V

CC

~ GND

V

ECHO

(11pin)

MIC ON and ECHO LEVEL CTRL MIC OFF

– 100

0

– 50

0

0.5 1.0

VECHO (11pin) P.P ratio : VECHO / VCC

MIC AMP IN ~ LINE OUT

(VIN = – 38dBV, f = 1kHz)

DLY BF IN ~ LINE OUT

(V

IN = – 4dBV, f = 1kHz)

LINE OUT Attenuation. : ATT (dB)

Fig. 2 LINE OUTattenuation ratio vs. Vecho (11pin)

partial pressure ratio

∗

These figures are for standard samples and

are not guaranteed standards.

(4) LOOP GAIN CTRL (pin 12)

• Adjusts the loop gain (pins 17 and 18).

0

0

0.5 1.0

V

CC = 9.0V

–50

–25

VLOOP (12pin) P.P ratio : VECHO / VCC

DLY BF IN

~

CMP BF OUT

(V

IN = – 4dBV, f = 1kHz)

CMP BF OUT Attenuation. : ATT (dB)

Fig. 3 CMP BF OUT attenuation ratio vs. Vloop

(pin 12) partial pressure ratio

∗

These figures are for standard samples and

are not guaranteed standards.

9

Multimedia ICs BA7726AS / BA7726AFS

(5) LPF

• Use the internal operational amplifier and an
attached capacitor and resistor to configure a tertiary
LPF for anti-aliasing and smoothing.

Cutoff frequency

LPF constant

Pass band gain

R

1 R2 R3 C1 C2 C3

2kHz 22kΩ 56kΩ 47kΩ 6800pF 4700pF 270pF 0.6dB
3kHz 18kΩ 47kΩ 39kΩ 5600pF 3900pF 220pF 0.7dB
4kHz 15kΩ 39kΩ 33kΩ 4700pF 3300pF 180pF 0.8dB

LPF constant examples (V

CC

= 9.0V)

∗

CMP OUT (pin 20) output is positively correlated with Vcc. When Vcc is a voltage other than 9.0V, set the pass band gain so that maximum CMP side LPF output

(input to BU9252) is 5Vp-p. Make sure that the EXP side LPF constant does not exceed the load drive capability (minimum = 0.3mA, typical 0.5mA).

20 19 18 17

16

–
+

–

+

R1

R2

C3

R1

R3

C2

C1

C3

R3

R2

R1

C2

C1

R1

TO BU9252

FROM BU9252

Fig. 4 LPF

(6) Vocal fader function

• After the synchronous component of the left and
right channels is eliminated, LPF output is added to
the signal, which is then output (see figure below).
The vocal component is difficult to remove from cer­tain types of sources.

56789

LINELINE

C2

C1

LPF

+

–

IN LIN R

TO OUTSW

Fig. 5 Vocal fader block

LPF constant examples

Cutoff frequency

LPF constant

C

1 C2

100Hz 0.022µF 0.1µF
150Hz 0.015µF 0.068µF
200Hz 0.01µF 0.047µF

∗

C1 and C2 are only necessary when using the vocal fader function.

(7) ALC level

• When Vcc is 9.0V, ALC level can be set roughly

between -4dBV and +9dBV, and is determined by the
voltage impressed on pin 28 (V

28, set with resistive

division between Vcc and the ground). ALC level is
calculated with the following equation, although slight
error occurs as V

28 approaches VCC.

0

0

V

CC = 9.0V

510

Set within this range

+ 10

+ 5

–5

–10

Pin 28 voltage: V28 (V)

ALC LEVEL : VOAML (dBV)

at LINE OUT (f = 1kHz)

Fig. 6 ALC level vs. pin 28 voltage

∗

These figures are for standard samples and

are not guaranteed standards.

VOAML ⱌ

1.0 ⬉ V

28 ⬉ 0.85 × (VCC – 1.0), at LINE OUT

1

2 × 2

× (V

CC – V28) [Vrms],

10

Multimedia ICs BA7726AS / BA7726AFS

(8) Microphone input detection function

• This function detects the signal input to MIC AMP IN

(pin 26) and outputs it to pin 30.

Pin 30 output

No signal input to MIC AMP IN (pin 26) GND

Signal input to MIC AMP IN (pin 26) V

CC – 1.0V

• The detection level is determined by the voltage

impressed on pin 29 (V

29, set with resistive division

between Vcc and the ground) and is calculated with
the following equation, although slight error occurs
as V28 approaches ground.

0

V

CC = 9.0V

510

Set within this range

–70

–20

at MIC AMP IN (f = 1kHz)

Pin 29 voltage: V29 (V)

Fig. 7 Microphone amplifier input detection level vs.

pin 29 voltage

∗

These are figures for standard samples and

are not guaranteed standards.

Microphone amplifier input

detection level : V

ODET

(dBV)

•

Application example

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

SW

DET

ALC

VR

–

+

EXPAND

COMPRESS

–

+

VR

VR

+ +

0.1µ

0.1µ

0.015µ

0.068µ

0.1µ

+

0.47µ

+

+

0.1µ

+1µ+

+

0.1µ

0.47µ

5600p

18k

47k

3900p

18k

39k

220p

47k

3900p

5600p

18k

1µ

+

18k

220p

39k

47µ

BA7726AFS

ECHO

LEVEL

56k
10k

10k

2.7k

0.1µ

+

987654321

10 11 12 13 14 15 16 17 18

1µ

+

1000p

+

10µ

0.1µ

ADRRESS COUNTER

MAIN TIMING

and

S

H

BU9252F

L / ST / R

f = 455kHz

L / VF / R

8 × 2k SRAM

2.2µ

2.2µ

MIC AMP IN

NO / VC CTRL

VCC 9V

VOCAL

VCC 5V

TEST

CIRCUIT

8bit

A / D

8bit

D / A

LINE OUT R

LINE OUT L

MUTE CTRL

LINE IN R

LINE IN L

MIC ON / OFF

LOOP GAIN

FADER

–

+

Fig.8

VODET ⱌ 0.03 × (

0.5 ⬉ V

29 ⬉ 0.85 × (VCC – 1.0), at MIC AMP IN

1

2 × 2

× V

29) [Vrms],

11

Multimedia ICs BA7726AS / BA7726AFS

•

Operation notes

(1) LINE OUT (pins 1 and 2) signal processing

• Be sure to attach a capacitor for phase correction to
the LINE OUT pins.

12

+ +

4700p

4700p

LINE OUT R

LINE OUT L

Fig. 9

(2) Setting the loop gain

• Set the LPF constant and pin 12 control voltage so
that the loop gain (1st echo wave / 2nd echo wave)
does not exceed 1. Be particularly careful of peak­ing near the LPF cutoff point.

(3) ALC function and microphone amplifier input

detection function

• Refer to items 7 and 8 in “Circuit description.” When
these functions are not used, be sure to ground pins
27 and 28 (the ALC function) and pins 29 and 30
(microphone amplifier input detection function).

•

External dimensions (Units: mm)

4.7 ± 0.3

0.51Min.

8.4 ± 0.3

3.2 ± 0.2

32

1

16

17

0.5 ± 0.1

0.3

± 0.1

28.0 ± 0.3

0° ~ 15°

10.16

1.778

SDIP32 SSOP-A32

BA7726AFSBA7726AS

0.15

0.15 ± 0.1

0.3Min.

7.8 ± 0.3

5.4 ± 0.2

1.8 ± 0.1

0.11

1

32

0.36 ± 0.1

16

17

13.6 ± 0.2

0.8