cx20493-35/app Conexant Systems, Inc., cx20493-35/app Datasheet - Page 18

• Manufacturer Part Number: cx20493-35/app
• Description: With Cx20493 Smartdaa?
• Manufacturer: Conexant Systems, Inc.

1.5.2
1.5.3
1.5.4
1.6
1-10
CX81801-7x/8x SmartV.XX Modem in 128-Pin LQFP with CX20493 in 32-Pin LQFP Data Sheet
Digital Isolation Barrier
CX20493 SmartDAA Line Side Device
CX20442 Voice Codec
AT Commands
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.
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.
The optional CX20442 Voice Codec (VC), packaged in a 32-pin LQFP, supports
voice/full-duplex speakerphone (FDSP) operation with interfaces to a microphone and
speaker and to a telephone handset/headset.
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.
Data Mode Operation. Data functions operate in response to the AT commands when
+FCLASS=0. Default parameters support U.S./Canada operation.
Conexant
102247B