CXA2509AQ View Datasheet(PDF) - Sony Semiconductor

Part Name

Description

Manufacturer

CXA2509AQ

Playback Equalizer Amplifier with Music Sensor

Sony Semiconductor 

CXA2509AQ

4. Music sensor

TAPEIN2

MSLPF

×1

R2

10k

R1

10k

R3

127k

AMP1

VGS

×1

C1 Vcc

64p

R4

100k

AMP2

Vcc

DVcc

Full-wave

rectifier

Smoother

AMP3

R11

MSOUT

R5

R6

39.1k 1k

R7

11.1k

DGND

DGND

DGND

TAPEIN1

G1FB

C2

R8

G2FB

C3

R9

MSTC

R10 C4

Fig. 5. Music sensor block diagram

The signal input from TAPEIN is added and amplified by AMP1.

This signal is then input to the LPF (R4 and C1). The LPF cut-off frequency can be adjusted by connecting the

external capacitance to MSLPF pin. The cut-off frequency is approximately 23kHz when MSLPF pin is left

open.

The detection level and HPF cut-off frequency are determined with the external resistance and capacitance

connected to G1FB or G2FB at AMP2, and the signal is converted to a current.

The signal is full-wave rectified and is converted to a voltage by the internal resistance R5.

The full-wave rectified signal is smoothed. The internal resistance (R6) and external capacitance (C4)

determine the smoothing response time. The recovery time is determined by the external resistance (R10) and

capacitance (C4).

The AMP3 comparator detects whether the smoothed signal is greater or smaller than the comparator

threshold.

The comparator has approximately 2dB hysteresis.

The table below shows the example of the constant and characteristics for the external resistance and

capacitance connected to G1FB and G2FB.

R

C

Music signal detection level

Music signal interval

detection level

Cut-off frequency

FF/REW (G1) 39kΩ 0.0047µF

–39.5dBm

–41.4dBm

870Hz

Playback (G2) 3.9kΩ 0.47µF

–59.5dBm

–61.4dBm

87Hz

Detection level

(dBm)

–39.5

–59.5

G1 (FF)

G2 (NOR)

87 870

Frequency (Hz)

Fig. 6. Music sensor circuit frequency response

– 16 –

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