Technical Note

5/15

www.rohm.com

2010.10 - Rev.A

© 2010 ROHM Co., Ltd. All rights reserved.

BD3870FS,BD3871FS,BD3872FS,BD3873FS

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Block diagram, application circuit, pin assignment (BD3870FS, BD3871FS, BD3873FS)

Unit: Resistance =Ω, Capacitor = F

Fig.2

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Pin description (BD3870FS, BD3871FS, BD3873FS)

Pin No. Pin Name

Description

Pin No. Pin Name

Description

1

VIN1

1ch volume input pin

13

SC

Serial clock input pin

2

VIN2

2ch volume input pin

14

SI

Serial data input pin

3

SEL2

2ch input selector output pin

15

VCC

Power supply pin

4

SEL1

1ch input selector output pin

16

OUT2

2ch output pin

5

A1

1ch input pin A

17

OUT1

1ch output pin

6

A2

2ch input pin A

18

BOUT1

1ch bass filter setting pin

7

B1

1ch input pin B

19

BNF1

1ch bass filter setting pin

8

B2

2ch input pin B

20

BOUT2

2ch bass filter setting pin

9

C1

1ch input pin C

21

BNF2

2ch bass filter setting pin

10

C2

2ch input pin C

22

TNF2

2ch treble filter setting pin

11

FILTER

1/2 VCC pin

23

TNF1

1ch treble filter setting pin

12

GND

Ground pin

24

CAP

Time constant setting pin for absorbing

surround switching shock sound

5.6k

5.6k

13

14

15

16

17

18

19

20

21

22

23

24

12

11

10

9

8

7

6

5

4

3

2

1

Treble1

fc=8k Hz

Treble２

fc=8kHz

Bass2

Bass1

Logic

Vcc/2

Vcc/2

Vcc/2

Vcc/2

Vcc/2

0dB

～

-87dB

-∞

50k

50k

50k

50k

50k

50k

10μ

10μ

47μ

10μ

10μ

10μ

10μ

10μ

10μ

4.7k

4.7k

A1

A2

B1

B2

C1

C2

CLOCK

DATA

LATCH

VCC

OUT2

OUT1

10μ

10μ

390k

390k

0.1μ

0.1μ 0.1μ

0.1μ

0.0022μ 0.0022μ

0.33μ