BA7726 データシートの表示（PDF） - ROHM Semiconductor

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BA7726

Analog compander with vocal fader for KARAOKE

ROHM Semiconductor 

Multimedia ICs

(8) Microphone input detection function

• This function detects the signal input to MIC AMP IN

(pin 26) and outputs it to pin 30.

No signal input to MIC AMP IN (pin 26)

Signal input to MIC AMP IN (pin 26)

Pin 30 output

GND

VCC – 1.0V

• The detection level is determined by the voltage

impressed on pin 29 (V29, set with resistive division

between Vcc and the ground) and is calculated with

the following equation, although slight error occurs

as V28 approaches ground.

VODET Լ 0.03 × (

1

2×

2

× V29) [Vrms],

0.5 Ϲ V29 Ϲ 0.85 × (VCC – 1.0), at MIC AMP IN

•Application example

BA7726AS / BA7726AFS

Set within this range

– 20

VCC = 9.0V

at MIC AMP IN (f = 1kHz)

– 70

0

5

10

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.

39k

+

+

++

+

18k 47k 220p

32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17

OUTSW

VOCAL

DET

ALC

VR

–

VOCAL

FADER

COMPRESS

VR

–

–

SW

VR

EXPAND

3900p

18k

1000p

1µ

+

1µ

+

8bit

A/D

S

and

H

+

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

++

+

+

0.015µ

56k

BA7726AFS

0.068µ

10k

10k

2.7k

LOOP GAIN

ECHO

LEVEL

BU9252F

0.1µ

Fig.8

10

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