DS28-L189-061 Ver la hoja de datos (PDF) - Conexant Systems

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DS28-L189-061

SmartSCM Modem

Conexant Systems 

SmartSCM Modem Data Sheet

The SCM performs the command processing and host interface functions. The crystal frequency is 28.224 MHz.

The SCM optionally connects to external OEM-supplied ROM/flash ROM and RAM over a non-multiplexed 19-bit address bus

and 8-bit data bus. GSM operation requires external 1M (128k x 8) ROM/flash ROM.

The SCM optionally connects to an external OEM-supplied serial EEPROM over a dedicated 2-line serial interface. The

capacity of the EEPROM can be 256 bytes up to 32k bytes. The EEPROM can hold information such as firmware

configuration customization, country code parameters, and cellular drivers.

The SCM performs telephone line signal modulation/demodulation in a hardware digital signal processor (DSP) which

reduces computational load on the host processor.

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

1.4.2 Digital Isolation Barrier

The OEM-supplied Digital Isolation Barrier (DIB) electrically DC isolates the SCM from the LSD and telephone line. The SCM

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 SCM to the LSD.

The DIB data channel supports bidirectional half-duplex serial transfer of data, control, and status information between the

SCM and the LSD over two lines.

1.4.3 CX20463 SmartDAA Line Side Device

The CX20463 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 SCM through the DIB.

LSD power is received from the MDP PWRCLKP and PWRCLKN pins via the DIB through a half-wave rectifying diode 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 SCM through the DIB_P and DIB_N pins. These pins connect to the SCM

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.

1.4.4 CX20437 Voice Codec

The optional CX20437 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. The VC also supports and

analog cellular operation with direct connect interface to a cellular phone (in lieu of telephone handset/headset connection).

1.5 Commands

The modem supports data modem, fax class 1 modem, fax class 1.0 modem, fax class 2 modem, voice/audio, full-duplex

speakerphone (FDSP), MNP 10/MNP 10EC, and V.80 commands, and S Registers in accordance with modem model

options. See Doc. No. 100722 for a description of the commands.

Data Modem Operation. Data modem functions operate in response to the AT commands when +FCLASS=0. Default

parameters support U.S./Canada operation.

MNP 10 Operation. MNP 10 functions operate in response to MNP 10 commands.

MNP 10EC Operation. MNP 10EC is enabled by the -SEC=1 command.

Fax Modem Operation. Facsimile functions operate in response to fax class 1 commands when +FCLASS=1, fax class 1.0

commands when +FCLASS=1.0, or to fax class 2 commands when +FCLASS=2 is installed.

1-8

Conexant

100490C

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