Datasheet BA3838F, BA3837F, BA3837 Datasheet (ROHM)

1

Multimedia ICs

Vocal fader IC

BA3837 / BA3837F / BA3838F

The BA3837, BA3837F and BA3838F are ICs with an internal secondary active LPF for vocal cancellation functions
and mixing amplifier functions with high degrees of vocal cancellation. Three control pins are used to switch between
modes: the key controller input mode, through mode, vocal fader mode, sound multiplexing mode and mute mode.
By offering these functions on a single chip, these ICs can significantly reduce the number of external components.

•

Applications

Karaoke functions on stereo systems, portable stereos and VCRs

•

Features

•

Absolute maximum ratings (Ta = 25°C)

1) Single-chip IC with vocal fader, to erase vocals from
commercially available recordings.

2) Internal secondary active LPF for high degrees of
vocal cancellation (high synchronization rejection).

3) Three control pins for switching between 4 modes:
through, vocal fader, sound multiplexing and mute.

4) Key controller input and internal switches.

5) Low noise and low distortion.

6) Internal microphone mixing amplifier.

7) Available in two packages: DIP 16-pin and SOP 16­pin (BA3838F is available in SOP 16-pin only).

Parameter Symbol Limits Unit

18 V

DIP16

Pd mV

SOP16

Topr °C
Tstg °C

V

CC

1000

∗

1

550

∗

2

– 40 ~ + 85
– 55 ~ + 125

Power supply voltage
Power

dissipation
Operating temperature

Storage temperature

∗

1 Reduced by 10 mW for each increase in Ta of 1°C over 25°C.

∗

2 Reduced by 5.5mW for each increase in Ta of 1°C over 25°C.

•

Recommended operating conditions (Ta = 25°C)

Parameter Symbol Min. Typ. Max. Unit

V

CC 5.4 — 10 V

V

CC 5.4 — 13 V

V

CC 4.0 — 15 V Ta = 25

°C

Ta = – 40°C ~ + 85°C
Ta = – 40°C ~ + 60°C

Conditions

Power supply voltage

∗

1

Power supply voltage

∗

1

Power supply voltage

∗

2

∗

2 BA3838F

∗

1 BA3837 and BA3837F

2

Multimedia ICs BA3837 / BA3837F / BA3838F

•

Block diagram

16 15 14 13 12 11 10 9

123456 78

LOGIC

SW2

SW1

R

L + R

L – R

L

+

+

–

–

+

–

+

+

–

–

+

–
+

–
+

V

CC MIC LOUT FK TK LIN BIAS GND

C B A ROUT LP LP LP RIN

3

Multimedia ICs BA3837 / BA3837F / BA3838F

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Pin descriptions

1V

CC

2 MIC IN

3LOUT

4FK

5TK

Pin No.

BA3837 / BA3837F

BA3838F

51k

20k

20k

51

k

400

5

5

4

3

2

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

1
2

V

CC

1
2

V

CC

V

CC

Pin name Equivalent circuit Function

Mixing input pin for microphone sound

Lch output pin

Input pin for key controller signals

Output pin for key controller signals

4

Multimedia ICs BA3837 / BA3837F / BA3838F

LIN

8

9 RIN

10 LPF1

LPF2

6

7

11

BIAS

GND

Pin No.

6

7

9

10

11

10

11

51k

51k

51k

51k

10.4k

10.4k

10.4k

10.4k

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

1
2

V

CC

1
2

V

CC

Pin name Equivalent circuit

L signal input pin

Signal bias circuit pin

R signal input pin

Function

LPF time constant pin

LPF time constant pin

5

Multimedia ICs BA3837 / BA3837F / BA3838F

12

13 ROUT

14 CONTA

15 CONTB

16 CONTC

LPF3

Pin No.

12

20k

13

20k

20k

15

16

14

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

V

CC

Pin name Equivalent circuit

LPF output pin

R output pin

Mode switching pin A

Mode switching pin B

Mode switching pin C

Function

6

Multimedia ICs BA3837 / BA3837F / BA3838F

Parameter Symbol Min. Typ. Max. Unit Conditions

I

Q

1.6 2.4 3.3 mA

V

om

2.3 2.8

—

G

VT

10 14 17 dB

G

VF

10 14 17 dB

G

VM

5 8 11 dB

CT 54 70

—

dB fIN =

1kHz

MU 73 80

—

dB fIN =

1kHz

SV 28 33

—

dB

THD

—

0.02 0.07 %

V

N

—

15 22

R

IN

35 50 65 k

Ω

VthH 4.7

——

V

VthL

—

—

0.3 V

∆

DC

—

726 mV

µ

Vrms

Vrms

—
—

—

Quiescent current
Maximum output voltage
L / R gain
Low frequency gain
Microphone gain
Crosstalk
Mute attenuation
Vocal suppression rate
Total harmonic distortion
Noise level
Input impedance

Output switching DC differential

Control pin threshold (high)
Control pin threshold (low)

䊊

Not designed for radiation resistance.

Through mode
THD

=

1%, through mode
Through mode
fin

=

50kHz, vocal fader mode

Vocal fader mode
Through mode, BW

:

400Hz - 30kHz

R

g

=

0, DIN AUDIO

LIN, RIN, MICIN, FK

Maximum output voltage differential between L, R and TK modes

0 : 0V 1 : 5V

A B C LOUT ROUT TK

0 0 0 MUTE MUTE MUTE
0 0 1 VF VF VF
0 1 0 L L L
0 1 1 L R L
1 0 0 MUTE MUTE MUTE

•

•

•

•

1 0 1 KC KC VF
1 1 0 KC KC L
1 1 1 KC KC L + R

—
—
—
—

Mute
Vocal fader mode
Sound multiplexing mode
Through mode
Mute
Vocal fader mode
Sound multiplexing mode
L + R

Key controller modeMode

VF : vocal fader output
KC : signal passed through key controller

1. L / R input and output in the through mode are synchronous with a gain of 14dB.

2. L / R input and TK output in the key controller mode are synchronous with a gain of 8dB.

3. FK input and L / R output in the key controller mode are synchronous with a gain of 6dB.

4.MIC input and L / R output are negative phase with a gain of 8dB.

(1) Microphone output is not muted during muting (ABC = 000 or 100).
(2) Gain and relative phase: See block diagram.

Mode table (A = pin14, B = pin15, C = pin16)

•

Electrical characteristics

BA3837 / F (unless otherwise noted, Ta = 25°C, Vcc = 10V, f

IN = 1kHz, VIN = 150mV, RL = 100kΩ)

7

Multimedia ICs BA3837 / BA3837F / BA3838F

BA3838F (unless otherwise noted, Ta = 25°C, Vcc = 10V, fIN = 1kHz, VIN = 150mV, Rl = 100Ω)

Parameter Symbol Min. Typ. Max. Unit Conditions

I

Q

1.9 2.7 3.6 mA

V

om

2.3 2.8

—

Vrms

G

VT

10 14 17 dB

G

VF

10 14 17 dB

G

VM

5 8 11 dB

CT 54 70

—

dB fIN =

1kHz

SV 28 33

—

dB

THD

—

0.02 0.07 %

V

N

—

15 22µVrms

R

IN

35 50 65 kΩLIN, RIN, MICIN, FK

VthH 4.7

——

V

VthL

——

0.3 V

∆

DC

—

746mV

—

—
—

Quiescent current
Maximum output voltage
L / R gain
Low frequency gain
Microphone gain
Crosstalk
Vocal suppression rate
Total harmonic distortion
Noise level
Input impedance
Control pin threshold (high)

Output switching DC differential

䊊

Not designed for radiation resistance.

Control pin threshold (low)

Through mode
THD

=

1%, through mode

fin

=

50kHz, vocal fader mode

Vocal fader mode

Maximum output voltage differential between L, R and TK modes

R

g

=

0, DIN AUDIO, through mode

Through mode

Through mode, BW

:

400Hz - 30kHz

0 : 0V 1 : 5V

A B C LOUT ROUT TK

0 0 0
0 0 1 VF VF VF
0 1 0 L L L
0 1 1 L R L
1 0 0

•

1 0 1 KC KC VF

•

1 1 0 KC KC L

•

1 1 1 KC KC L + R

•

KC

RRKCR

R

—
—
—
—

1. Gain of L / R input and output in the through mode: 14 dB (synchronous)

2. Gain of L / R input and TK output in the key controller mode: 8dB (synchronous)

3. Gain of FK input and L / R output in the key controller mode: 6dB (synchronous)

4. MIC input and L / R output are negative phase with a gain of 8dB.

∗

Gain and relative phase: See block diagram.

VF : vocal fader output
KC : signal passed through key controller

Vocal fader mode

Through mode

Vocal fader mode

L + R

Sound multiplexing mode (ROUT)

Sound multiplexing (LOUT)

Sound multiplexing (R)

Sound multiplexing mode (L)

Mode Key controller mode

Mode table (A = pin14, B = pin15, C = pin16)

8

Multimedia ICs BA3837 / BA3837F / BA3838F

A

A

A

A

V

V

4.7V

0.3V

100k

AUDIO
ANALYZER

MEASUREMENT

600Ω

OSC

51k

MIC

FK

L

10µ

+

10µ 10µ 10µ 22µ

C1 C2 C3 C4

++ ++

C7

0.22µ

0.047µ
C5

C6

10µ

+

16 15 14 13 12 11 10 9

12 34567 8

C B A Rout LP LP LP RIN

V

CC MICIN Lout FK TK LIN BIAS GND

R

Fig. 1

•

Measurement circuit (BA3838F)

9

Multimedia ICs BA3837 / BA3837F / BA3838F

µ – CON

51k 51k 51k

1µ 1µ 1µ

+++

0.22µ

0.047µ

10µ

+

TAPE, CD
LD, etc.

10µ

+

+

22µ

Key

– con

10µ

+

POWER

AMP

MICROPHONE

MICROPHONE

+

16 15 14 13 12 11 10 9

12345678

Fig. 2

•

Application example (BA3838F)

•

Operation notes

(1) The example in the diagram “Application example”

is recommended with confidence. However, be
sure to comply with these precautions and verify
characteristics during actual use. Also, when
changing an attached circuit constant, be sure to
allow sufficient margins by taking into account both
static and transient characteristics, including varia­tion in these ICs and the attached components.

(2) The low pass filter cutoff frequency is determined

by the internal circuitry and by C

6 and C7 in Fig. 1.

With the constant used in Fig. 1, the cutoff fre­quency (fc) is roughly 150Hz. This cutoff frequen­cy can be changed by changing C

6 and C7. When

C

6 is multiple a, and C7 is multiple b, respectively,

the cutoff frequency is calculated thus:

(3) For the gain and relative phase of the input pin

(LIN, RIN, MICIN and FK) inputs and output pin
(LOUT, ROUT and TK) outputs, refer to “Gain and
relative phase,” on page 2 / 10.

(4) Electrical characteristics are measured at a load

resistance (R

L) of roughly 100kΩ. As using an

extremely low load resistance (below 10kΩ) will
result in slight variation in maximum output voltage
and total harmonic distortion, caution must be
used when designing connections with the subse­quent stage.

(5) The pin 7 bias voltage is roughly Vcc / 2. Because

this is also the input and output pin voltage, select
coupling capacitor polarity according to relative
potential and the characteristics of the compo­nents to which the coupling capacitor is to be con­nected.

(6) When outputting L + R from LOUT and ROUT in

an application in which the key controller is left
unconnected, attach a 10µF electrolytic capacitor
between pins 4 and 5, with pin 5 being positive (L
+ R mode: ABC = 111).

(7) Connecting a capacitance load to pin 5 (TK) of

BA3837 / F can worsen noise characteristics.
When connecting a capacitance load higher than
10µF, insert 1kΩ in series (Figs. 1 and 2). The pin
5 output impedance is roughly 5Ω (1kHz). In the
BA3838F it is roughly 400Ω (1kHz).

(8) The vocal fader works by canceling out the syn-

chronous component of the signal, leaving the low
components in place. Consequently, the vocal
fader may not be very effective with certain
recordings.

(9) In cases where output DC differential can cause

noise when switching between modes, use a time
constant for the timing of control pin switching, or
take some other measure.

(10) Operating supply voltage may vary according to

ambient temperature. Using this IC outside the
recommended supply voltage range may result in
increased crosstalk or mute attenuation.

10

Multimedia ICs BA3837 / BA3837F / BA3838F

QUIESCENT CURRENT : IQ (mA)

POWER SUPPLY VOLTAGE : VCC (V)

0 2 4 6 8 101214161820

4

3

2

1

5

Fig. 3 IQ vs. VCC characteristics
(BA3837 / F)

QUIESCENT CURRENT : IQ (mA)

POWER SUPPLY VOLTAGE : VCC (V)

02468101214161820

4

3

2

1

5

Fig. 4 IQ vs. VCC characteristics
(BA3838F)

FREQUENCY : f (Hz)

VOCAL COMRESSION RATIO : SV (dB)

10 100 1K

10K 100K

40

20
14

0

– 20

– 40

– 60

Fig. 5 SV vs. frequency

characteristics

•

Electrical characteristic curves

The value of Q is: Q =
(Currently, Q ⱌ 1)

12C7

C6

150

ab

(Hz)

fc =

11

Multimedia ICs BA3837 / BA3837F / BA3838F

TOTAL HARMONIC DISTORTION : THD (%)

INPUT LEVEL : VIN (dBV)

L,R OUTPUT

– 40 – 30 – 20

– 10 0

10

10

1

0.1

0.01

0.001

Fig. 6 THD vs.

V

IN characteristics

•

External dimensions (Units: mm)

DIP16

BA3837

SOP16

BA3837F / BA3838F

0.51Min.

0.3

± 0.1

916

81

6.5

± 0.3

3.2 ± 0.2

4.25 ± 0.3

0.5

± 0.1

19.4 ± 0.3

2.54

0° ~ 15°

7.62

0.4 ± 0.11.27

0.15

0.15 ± 0.1

0.3Min.

4.4 ± 0.2

6.2 ± 0.3

0.11

1.5 ± 0.1

1

16

10.0 ± 0.2

8

9