HA12215 Просмотр технического описания (PDF) - Hitachi -> Renesas Electronics

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HA12215

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

Hitachi -> Renesas Electronics 

HA12215F

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.

Time constant of detection

Figure 6(1) generally shows that detection time is in proportion to value of capacitor C13. But, with

Attack*2 and Recovery*3 the detection time differs exceptionally.

Notes 2. Attack : Non- music to Music

3. Recovery : Music to Non-music

Recovery

Attack

Recovery

Attack

Recovery

Attack

C13

R13

Detection level Input level

(1)

(2)

(3)

Figure 6 Function Characteristic of MS

Like the figure 6(2), Recovery time is variably possible by value of resistor R13. But Attack time gets

about fixed value. Attack time has dependence by input level. When a large signal is inputted, Attack time

is short tendency.

Rev.5, Oct. 1999, page 12 of 69

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