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MSM7580

ITU-T G.721 ADPCM TRANSCODER

Oki Electric Industry 

¡ Semiconductor

MSM7580

PIN AND FUNCTIONAL DESCRIPTIONS

GND

Ground, 0 V.

SIP1, SOP1

PCM serial data input (SIP1) and output (SOP1) for Channel 1.

SOP1 is an open-drain output, which goes into a high impedance state after a continuous 8-bit

serial data output.

SIP2, SOP2

PCM serial data input (SIP2) and output (SOP2) for Channel 2.

SOP2 is an open-drain output, which goes into a high impedance state after a continuous 8-bit

serial data output.

PAD/ MUTE

Control input for the selection of PAD or MUTE mode.

When digital "1" is input, the PAD mode is selected and when digital "0" is input, the MUTE mode

is selected.

THR1, THR2

Control pins for the data through modes.

THR1 and THR2 are for Channel 1 and Channel 2, respectively. The data-through mode is

selected when digital “1” is applied to THR1 and THR2. In this mode, 8-bit serial input data

applied to SIA1 and SIA2 (ADPCM data input) is passed to the PCM serial data output pins,

SOP1 and SOP2, without any data modification. SOP1 and SOP2 go to the high impedance state

after the output of 8-bit data has been applied to SIA1 and SIA2.

Conversely 8-bit serial input data applied to SIP1 and SIP2 (PCM data input) is passed to

ADPCM serial data output pins, SOA1 and SOA2, without any data modification.

SOA1 and SOA2 go to the high impedance state after the output of 8-bit data has been applied

to SIP1 and SIP2.

Since ADPCM and PCM data interfaces have the mutually independent signal input pins for

synchronizing signals the time slots for data input and output can be exchanged between them.

Some timing at which data may be deleted or duplicated as described in "Notes on Usage" should

not be used.

MUTE1, MUTE2

Setting a digital "1"at these pins sets the PCM output to the idle pattern state regardless of the

ADPCM input data, when the MUTE mode is selected by the PAD/MUTE pin.

When the PAD mode is selected, the PCM output has a 12 dB loss.

Normally, these pins are set to a digital "0".

When the data through mode is selected, the function of these pins is invalid.

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