CX81801-74 Просмотр технического описания (PDF) - Conexant Systems

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CX81801-74

SmartV.XX Modem

Conexant Systems 

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CX81801-7x/8x SmartV.XX Modem Data Sheet

The CX81801 optionally connects to external OEM-supplied ROM/flash ROM and RAM

over a non-multiplexed 19-bit address bus and 8-bit data bus.

Digital Isolation Barrier

The OEM-supplied Digital Isolation Barrier (DIB) electrically DC isolates the CX81801

from the LSD and telephone line. The modem is connected to a fixed digital ground and

operates with standard CMOS logic levels. The LSD is connected to a floating ground

and can tolerate high voltage input (compatible with telephone line and typical surge

requirements).

The DIB transformer couples power and clock from the CX81801 to the LSD.

The DIB data channel supports bidirectional half-duplex serial transfer of data, control,

and status information between the CX81801 and the LSD over two lines.

CX20493 SmartDAA Line Side Device

The CX20493 SmartDAA Line Side Device (LSD) includes a Line Side DIB Interface

(LSDI), a coder/decoder (codec), and a Telephone Line Interface (TLI).

The LSDI communicates with, and receives power and clock from, the SmartDAA

interface in the CX81801 through the DIB.

LSD power is received from the MDP PWRCLKP and PWRCLKN pins via the DIB

through a full-wave rectified bridge and capacitive power filter circuit connected to the

DIB transformer secondary winding.

The CLK input is also accepted from the DIB transformer secondary winding through a

capacitor and a resistor in series.

Information is transferred between the LSD and the CX81801 through the DIB_P and

DIB_N pins. These pins connect to the CX81801 DIB_DATAP and DIB_DATAN pins,

respectively, through the DIB.

The TLI integrates DAA and direct telephone line interface functions and connects

directly to the line TIP and RING pins, as well as to external line protection components.

Direct LSD connection to TIP and RING allows real-time measurement of telephone line

parameters, such as the telephone central office (CO) battery voltage, individual

telephone line (copper wire) resistance, and allows dynamic regulation of the off-hook

TIP and RING voltage and total current drawn from the central office (CO). This allows

the modem to maintain compliance with U.S. and worldwide regulations and to actively

control the DAA power dissipation.

CX20442 Voice Codec

The optional CX20442 Voice Codec (VC), packaged in a 32-pin TQFP, supports

voice/full-duplex speakerphone (FDSP) operation with interfaces to a microphone and

speaker and to a telephone handset/headset.

AT Commands

The SmartV.XX Modem supports AT commands for data mode, fax class 1 or 1.0,

voice/audio, full-duplex speakerphone (FDSP), V.80 commands, and S Register. See

Doc. No. 102184 for a description of the commands.

Conexant

102199B

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