MSM7731-02 データシートの表示（PDF） - Oki Electric Industry

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MSM7731-02

Dual Echo Canceler & Noise Canceler with Dual Codec for Hands-Free

Oki Electric Industry 

1Semiconductor

FEDL7731-02-04

MSM7731-02

NCSEL1, NCSEL2

These are the noise attenuation selection pins. In the “through mode” the noise canceler is halted and data is

directly output. In the “normal mode” the noise canceler operates normally. Since the noise attenuation in the

normal mode is selected after the initial mode has been released, the change of the noise attenuation during normal

operation is invalid. If the noise attenuation is changed, reset must be activated by the RDN/RST pin or the

PDN/RST bit (CR0-B7). Changing to the through mode during normal operation and returning to the normal mode

are possible. The NCSEL1 pin is ORed with the CR1-B0 bit of the control register and the NCSEL2 pin is ORed

with the CR12-B2 bit of the control register. Refer to the section “RELATIONSHIP BETWEEN PINS AND

CONTROL REGISTERS”.

Note:

Since there is a trade-off between noise attenuation and sound quality after canceling the noise, select the noise

attenuation appropriate to the sound quality.

NCSEL2

0

1

1

0

NCSEL1

0

1

0

1

NC Mode

Normal Mode

Normal Mode

Normal Mode

Through Mode

Attenuation (dB)

17

13.5

8

—

Quality

Better

Best

—

NCPAD1, NCPAD2

These are the noise canceler I/O gain adjusting pins. The gain adjustment is valid for tone control after canceling

the noise. The bigger the input level of the noise canceler is, the better the sound quality is. The NCPAD1 pin is

ORed with the CR4-B2 bit of the control register and the NCPAD2 pin is ORed with the CR5-B2 bit of the control

register. Refer to the section “RELATIONSHIP BETWEEN PINS AND CONTROL REGISTERS”.

NCPAD2

0

0

1

1

NCPAD1

0

1

0

1

GPADNC (dB)

0

6

12

18

LPADNC (dB)

0

–6

–12

–18

DEN, EXCK, DIN, DOUT

This is the serial port for the microcontroller interface. 13 bytes of control registers are provided in this IC device.

There pins are used to write and read data from an external microcontroller. The DEN pin is an enable signal input

pin, the EXCK pin is a clock signal input pin for data shifting, the DIN pin is an address and data input pin, the

DOUT pin is a data output pin. If the mirrocontroller interface is not used, set the DEN pin to a logic “1” and the

EXCK and DIN pins to a logic “0”. In addition, use the MCUSEL pin to specify the “unused” setting of the

microcontroller interface. Figure 4 shows the input timing.

MCUSEL

This pin selects whether the microcontroller interface is used or unused. A logic “0” specifies that the

microcontroller interface is used and a logic “1” specifies that it is not used. If the microcontroller interface is not

used, this pin must be set to a logic “1”. This pin is ORed with the CR0-B1 bit of the control register. Refer to the

section “RELATIONSHIP BETWEEN PINS AND CONTROL REGISTERS”.

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