si2401 Silicon Laboratories, si2401 Datasheet - Page 12

• Manufacturer Part Number: si2401
• Description: V.22bis Isomodem With Integrated Global Daa
• Manufacturer: Silicon Laboratories

Si2401
4. Functional Description
The Si2401 is a complete modem chipset with
integrated direct access arrangement (DAA) that
provides a programmable line interface to meet global
telephone line requirements. Available in two 16-pin
small-outline packages, this solution includes a DSP
data pump, modem controller, codec, and DAA.
The modem accepts simple modem AT commands and
provides connect rates up to 2400 bps full-duplex over
the Public Switched Telephone Network (PSTN) with
V.42 hardware support through HDLC framing. To
minimize handshake times, the Si2401 can implement a
V.22-based fast connect. The modem also supports the
V.23 reversing protocol and standard alarm formats
including SIA.
This device is ideal for embedded modem applications
due to its small board space, low power consumption,
and global compliance. The Si2401 solution integrates a
silicon DAA using Silicon Laboratories’ proprietary third-
generation DAA technology. This highly-integrated DAA
12
V.21
V.22
V.22bis
V.23
V.23
Bell 103
Bell 212A
Security
SIA—Pulse
SIA Format
*Note: The Si2401 only adjusts its DCE rate from 2400 bps to 1200 bps if it is connecting to a V.22-only (1200 bps only)
*
modem. Because the V.22bis specification does not outline a fallback procedure, the host should implement a
fallback mechanism consisting of hanging up and connecting at a lower baud rate. Retraining to accommodate
changes in line conditions that occur during a call must be implemented by terminating the call and redialing.
Configuration
*
Modulation
Table 7. Selectable Configurations
DPSK
DPSK
DTMF
Pulse
QAM
FSK
FSK
FSK
FSK
Rev. 1.0
Frequency (Hz)
1080/1750
1200/2400
1200/2400
1300/2100
1300/1700
1170/2125
1200/2400
1170/2125
can be programmed using the Si3010 to meet
worldwide PTT specifications for ac termination, dc
termination, ringer impedance, and ringer threshold.
The DAA can also monitor line status for parallel
handset detection and overcurrent conditions.
The Si2401 is designed for rapid assimilation into
existing modem applications. The device interfaces
directly through a UART to a microcontroller. The
Si2401URT-EVB evaluation board connects directly to a
standard RS-232 interface. This allows for evaluation of
the
HyperTerminal or any standard terminal software.
The chipset can be fully programmed to meet
international telephone line interface requirements with
full compliance to FCC, TBR21, JATE, and other
country-specific PTT specifications. In addition, the
Si2401 has been designed to meet the most stringent
worldwide requirements for out-of-band energy, billing-
tone
requirements.
Carrier
—
—
modem
immunity,
300 half-duplex
immediately
Data Rate
high-voltage
1200/75
600/75
(bps)
1200
2400
1200
Low
300
300
40
upon
surges,
Full; plus reversing
Compliance
300 bps only
No retrain
Standard
(Europe)
powerup
Full
Full
Full
Full
Full
Full
and
safety
via