MSM7731-01 データシートの表示（PDF） - Oki Electric Industry

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MSM7731-01

Multifunction PCM CODEC (Voice Signal Processor)

Oki Electric Industry 

¡ Semiconductor

MSM7731-01

ECSEL

This is the echo canceler mode selection pin. A logic "1" selects the single echo canceler mode

and a logic "0" selects the dual echo canceler mode. Since this pin is ORed with the CR0-B0 bit

of the control register, set the pin to a logic "0" when controlling by the control register. If the

pin setting is changed, reset must be activated by either the PDN/RST pin or the PDN/RST bit

(CR0-B7). If the single echo canceler mode is selected, echo canceler control on the line-side is

unnecessary.

LTHR/ATHR

This is the "through mode" control pin for the echo canceler. In the "through mode", SinL/A and

RinL/A data is directly output to SoutL/A and RoutL/A respectively while each respective

echo coefficient is maintained. A logic "0" selects the normal mode (echo canceler operation) and

a logic "1" selects the "through mode." Since this pin is ORed with the CR4-B7 and CR5-B7 bits

of the control register, set the pin to a logic "0" when controlling the "through mode" by the

control register. Because data is shifted into this pin in synchronization with the rising edge of

the SYNC signal, hold the data at the pin for 250 ms or longer. For further details, refer to the

electrical characteristics.

LHD/AHD

This pin turns ON or OFF the function to detect and cancel the howling that occurs in an acoustic

system such as a handsfree communication system. A logic "0" turns the function ON and a logic

"1" turns the function OFF. Since this pin is ORed with the CR4-B4 and CR5-B4 bits of the control

register, set the pin to a logic "0" when controlling by the control register. Because data is shifted

into this pin in synchronization with the rising edge of the SYNC signal, hold the data at the pin

for 250 ms or longer. For further details, refer to the electrical characteristics.

LHLD/AHLD

This pin controls the updating of adaptive FIR filter coefficients for the echo canceler. A logic

"0" selects the normal mode (coefficient updating) and a logic "1" selects the fixed coefficient

mode. Since this pin is ORed with the CR4-B2 and CR5-B2 bits of the control register, set the pin

to a logic "0" when controlling by the control registers. Because data is shifted into this pin in

synchronization with the rising edge of the SYNC signal, hold the data at the pin for 250 ms or

longer. For further details, refer to the electrical characteristics.

LATT/AATT

This pin turns ON or OFF the ATT function to prevent howling by means of attenuators

(ATTsL/A, ATTrL/A) provided in the RinL/A inputs and SoutL/A outputs of the echo

canceler. If input is only to RinL/A, the ATTsL/A for SoutL/A is activated. If input is only to

SinL/A, or if there is input to both SinL/A and RinL/A, the ATTrL/A for RinL/A input is

activated. The ATT value of each attenuator is approximately 6 dB. A logic "0" turns ON and

a logic "1" turns OFF the ATT function. Since this pin setting is logically ORed with the CR4-

B1 and CR5-B1 bits of the control register, set the pin to a logic "0" when controlling by the control

register. Because data is shifted into this pin in synchronization with the rising edge of the SYNC

signal, hold the data at the pin for 250 ms or longer. For further details, refer to the electrical

characteristics.

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