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 selec-
tion 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 = 25C)
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 = 25C)
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
1
2
3
4
5
6
7
8
9
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
V
CC
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
100k
7
VF LPF1
Vocal fader mode LPF capacitor
4.5V
23.5k
8
VF LPF2
Vocal fader mode LPF capacitor
4.5V
70.5k
9
VF LPF3
Vocal fader mode LPF capacitor
4.5V
EF (NPN), 15k
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
50k
14
EXP DET CT
Expand attack / recovery time setting
Attack R = 5.6k
, recovery R = 85.6k
--
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 = 5.6k
, recovery R = 85.6k
--
22
CMP DET
Compression detection wave
4.5V
60k
23
V
CC
V
CC
9.0V
--
24
BIAS
Bias and capacitor for ripple rejection
4.5V
23.5k
25
MIC AMP NF
Microphone amplifier negative feedback
4.5V
2k
26
MIC AMP IN
Microphone amplifier input
4.5V
100k
27
ALC DET
ALC attack / recovery time setting
--
220
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
--
1k
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.
V
CC
3.3V
1.7V
3
V
CC
85k
15k
11
39k
31
V
CC
49.5k
33k
V
CC
3.3V
1.7V
39k
0.6
V
CC
0.8
V
CC
0.6
V
CC
0.8
V
CC
12
32
2.5V
150k
4
39k
39k
39k
39k
39k
39k
L / VF / R CTRL
MUTE CTRL
LOOP GAIN CTRL
ECHO LEVEL CTRL
NO / VC CTRL
L / ST / R CTRL
V
CC
5
Multimedia ICs
BA7726AS / BA7726AFS
Electrical characteristics (unless otherwise noted, Ta = 25C, 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
V
IN
= 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
V
CC
)
Interchannel crosstalk
CT
LL
--
85
--
dBV
MIC OFF (V
ECHO
= 0.1
V
CC
)
Mute level
MT
--
100
85
dBV
MUTE (V
MUTE
= H)
MIC OFF (V
ECHO
= 0.1
V
CC
)
Through mode output level
V
OLLV
1.0
0.0
+ 1.0
dBV
V
IN
= 12dBV
V
OLL1
1.0
0.0
+ 1.0
dB
V
OLL2
--
35
28
dB
Microphone through output level
V
OML
9.9
8.4
6.9
dBV
V
IN
= 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
V
CC
)
ALC level
V
OAML
+ 5.1
+ 6.6
+ 8.1
dBV
V
28
= 2.9V
Compress output level
V
OMC
5.5
3.5
1.5
dBV
V
IN
= 38dBV
Compress characteristics
CMP
--
+ 5.2
--
dB
V
IN
= 43dBV
33dBV
Output level differential
Expand output level
V
ODL
9.4
7.4
--
dBV
V
IN
= 4dBV
Expand characteristics
EXP
--
+ 19.4
--
dB
Echo EVR attenuation ratio
--
50
40
dB
Loop output level
V
ODC
4.4
2.4
--
dBV
V
IN
= 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
V
ODL
LOOP GAIN = Min. (V
LOOP
= 0.2
V
CC
)
V
IN
= 4dBV and when V
IN
= Vodc
ECHO LEVEL = Min. (V
ECHO
= 0.2
V
CC
)
V
IN
= 4dBV and when V
IN
= Vodl
V
IN
= 9dBV
+ 1dBV, Output level differential
(V
LSTR
= H, V
LVFR
= OPEN, V
NOVC
= OPEN)
V
IN
= 12dBV (dual ch.in.),VOCAL FADER
(V
LSTR
= H, V
LVFR
= OPEN, V
NOVC
= OPEN)
V
IN
= 12dBV (single ch. in.),VOCAL FADER
MIC OFF (V
ECHO
= 0.1
V
CC
)
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 (V
NOVC
= GND, V
LSTR
= OPEN, V
LVFR
= OPEN)
ECHO LEVEL = Max. (V
ECHO
= V
CC
), LOOP GAIN = Max. (V
LOOP
= V
CC
)
Signal frequency : 1kHz,
1 : B.W. = 0.4 ~ 30kHz,
2 : DIN AUDIO
V
IN
= 20.0dBV
1
No input, Rg = 1k
2
V
IN
12dBV, Rg = 1k
2
V
IN
= 12dBV, Rg = 1k
2
THD = 1%
1
Rg = 1k
2
V
IN
= 30dBV
2
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