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CX86500-66

V.92/V.34/V.32bis Modem in 28-Pin or 38-Pin TSSOP with CX20493 SmartDAA®

Conexant Systems 

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CX86500 SCXV.xx Modem Data Sheet

Hardware Description

CX86500 Modem

The CX86500 modem, packaged in a 28-pin TSSOP and 38-pin TSSOP, includes a

Microcontroller (MCU), a Modem Data Pump (MDP), internal ROM, internal RAM, and

SmartDAA interface functions.

The modem connects to host via a logical V.24 (EIA/TIA-232-E) serial DTE interface or

a parallel 16550 UART-compatible host interface (38-pin only).

The modem MCU/DSP performs the command processing, host interface functions and

telephone line signal modulation/demodulation which reduces computational load on the

host processor.

The SmartDAA Interface communicates with, and supplies power and clock to the LSD

through the DIB.

Digital Isolation Barrier

The OEM-supplied Digital Isolation Barrier (DIB) electrically DC isolates the CX86500

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 CX86500 to the LSD.

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

and status information between the CX86500 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 CX86500 through the DIB.

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

through a full-wave rectifier 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 CX86500 through the DIB_P and

DIB_N pins. These pins connect to the CX86500 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

Conexant

102287F

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