www.rohm.com

2015.06 - Rev.D

© 2015 ROHM Co., Ltd. All rights reserved.

Technical Note

6/8

BH3544F,BH3547F,BH3548F

●

Application circuit

5

6

7

8

3

4

OUT2

BIAS

IN2

47µ

1µ

90k

90k

6dB

6dB

BIAS

MUTE

TSD

2

1

OUT1

MUTE

IN1

GND

1µ

1µ

100k

330µ

10

VMUTE

H : Active

L : Mute

330µ

R5

C5

C6

C7

C8

C1

C2

C3

R3

R2

µ

+

+

+

+

Fig. 15

●

Description of external components

1) Input coupling capacitors (C3, C5)

These are determined according to the lower cutoff frequency fc. Moreover, since lowering the capacitance can cause

the occurrence of pop noise, when changing this, determine it after adequate checking.

Since the input impedance is 90kΩ, these are found by the expressions below, although drift, temperature

characteristics, and other considerations are necessary. (Layered ceramic capacitors are recommended.)

C3(C5)=1/(2π× 90kΩ×fc)

2) Bias capacitor (C6)

When VCC=5V, 47μF is recommended. Since lowering the capacitance too much can cause worsening of electrical

characteristics or the occurrence of pop noise, when changing this, determine it after checking this adequately.

3) Mute pin pop noise countermeasures (R2, C2)

Since BH3544F,BH3548F have an impedance of 190kΩ against GND and the BH3547F has 200kΩ, it may be

impossible to cancel mute mode if R2 is made too large.

4) Output coupling capacitors (C1, C7)

put in for output protection or current restriction), these are found by the expression below.

5) Input gain adjustment resistances (R3, R5)

Externally attached resistances (R3, R5) make input gain adjustment possible. The gain found by the expression

below can be set.

When input gain is not accommodated, these resistors have no use.