MSM7503 Просмотр технического описания (PDF) - Oki Electric Industry

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MSM7503

Multi-Function PCM CODEC

Oki Electric Industry 

¡ Semiconductor

MSM7503

TPAI, TPAO

The transmit pre-amplifier (A) input and output.

TPAI is the input and TPAO is the output. TPAI should be connected to the microphone of

handset via an AC-coupling capacitor if the DC offset appears at a transmit signal (offset from

SGT). The transmit path from TPAI to TPAO is always active regardless of processor control.

During the whole system power down mode, TPAO is at an analog ground level. The gain

between TPAI and TPAO is fixed to 20 dB.

SGT

Transmit path signal ground.

SGT outputs half the supply voltage. During the whole power down mode, SGT output is in a

high impedance state.

SGC

Bypass capacitor connecting pin for a signal ground level.

Insert a 0.1 mF high performance capacitor between SGC and AG.

VA, VD

+5 V power supply.

VA is for an analog circuit and VD is for a digital circuit. Both VA and VD should be connected

to the +5 V analog path of the system.

CAI, CAO

CODEC analog input and output.

CAI is the analog input of CODEC to be connected to the TO pin. If the DC offset voltage on the

TO signal is great, CAI should be connected via AC-coupling capacitor. At this time, insert an

about 100 kW bias resistor between CAI and SGT.

CAO is the analog output of CODEC. CAO should be connected to R1I via AC-coupling

capacitor.

A bias resistor is not required to R1I. During the whole system or CODEC power down mode,

CAO is at the SG voltage level.

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