HA12215F Просмотр технического описания (PDF) - Renesas Electronics

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HA12215F

Audio Signal Processor for Cassette Deck (Dolby B-type NR with Recording System)

Renesas Electronics 

HA12226F/HA12227F

The Sensitivity Adjustment of Music Sensor

Adjusting MS Amp gain by external resistor, the sensitivity of music sensor can set up.

REP

VCC

D VCC

PB (L)

−6dB

C16 R13

1000p 330k

+ C13

0.33µ

8.2k

LPF

25kHz

MAI

MA MSIN MS

RL

100k

OUT

DET

−

+

MS AMP

DET

50k

MS OUT

GND

Microcomputer

GND

PB (R)

Figure 4 Music Sensor Block Diagram

The Sensitivity of Music Sensor

A standard level of MS input pin 25.9 mVrms, therefore, the sensitivity of music sensor (S) can request it, by lower

formulas.

A = MS Amp Gain*1

B = PB input Gain × (1/2)*2

C = Sensed voltage

S = 20log

C

[dB]

25.9 ⋅ A ⋅ B

20log (A × B) = D [dB]

S = 14 − D [dB]

C = 130 [mVrms] (Intenally voltage in a standard)

PB input Gain = 21.3 [dB]

Notes: 1. When there is not a regulation outside.

2. Case of one-sided channel input.

But necessary to consider the same attenuation quantity practically, on account of A(B) have made frequency

response.

GV

37.7dB

f1

=

2π

⋅

1

C16

⋅

50k

[Hz]

f2 = 25k [Hz]

f

f1

f2

Figure 5 Frequency Characteristic of MSIN

Occasion of the external component of figure 4, f1 is 3.18 kHz.

Rev.6.00 Jun 15, 2005 page 12 of 83

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