SI2401-FS Silicon Laboratories Inc, SI2401-FS Datasheet - Page 16

• Manufacturer Part Number: SI2401-FS
• Description: IC ISOMODEM SYSTEM-SIDE 16SOIC
• Manufacturer: Silicon Laboratories Inc
• Type: Integrated Global DAAr

Specifications of SI2401-FS

• Package / Case: 16-SOIC (3.9mm Width)
• Data Format: V.21, V.22, V.23, Bell 103, Bell 212A
• Baud Rates: 2.4k
• Interface: UART
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Product: Modem Chip
• Supply Voltage (min): 3 V
• Supply Current: 15 mA
• Maximum Operating Temperature: + 100 C
• Minimum Operating Temperature: - 10 C
• Mounting Style: SMD/SMT
• Package: 16SOIC
• Main Category: Chipset
• Sub-category: ISOmodem
• Maximum Data Rate: 2.4 Kbps
• Typical Operating Supply Voltage: 3.3 V
• Power Supply Type: Digital
• Typical Supply Current: 10 mA
• Minimum Operating Supply Voltage: 3 V
• Maximum Operating Supply Voltage: 3.6 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 336-1167 - BOARD EVAL SI2401 UART INTERFACE
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 336-1095

Si2401/Si3008
result code is sent. The INT pin is also asserted if
enabled.
4.5.2. Loss-of-Carrier Detection
The Si2401 has two methods of implementing a loss-of-
carrier function. If GPIO4 is programmed as INT and if
S08[7](CDM) = 1, INT asserts in data mode when a
loss-of-carrier is detected. The carrier detect function
may also be implemented on GPIO2 by setting SE2[3:2]
(GPIO2) = 01 and SOC[7](CDE) = 1.
4.5.3. Caller ID Decoding Operation
The Si2401 supports full caller ID detection and decode
for US Bellcore and UK standards. To use the caller ID
decoding
necessary:
1. Set SE0[3] (ND) = 0
2. Set S0C[6:5] (CIDM) = 01 (set modem to Bellcore
4.5.4. Caller ID Monitor/Bellcore Caller ID
The Si2401 continuously monitors the phone line for the
caller ID mark signals. This can be useful in systems
that require detection of caller ID data before the ring
signal, voice mail indicator signals, and Type II caller ID
monitor support. To force the Si2401 into caller ID
monitor mode, set SOC[6:5] (CIDM) = 11.
Note: CIDM should be disabled before going off-hook.
4.5.5. UK Caller ID Operation
The Si2401 starts searching for the Idle State Tone Alert
Signal. When this signal has been detected, the Si2401
transmits an “a” to the host. After the Idle State Tone
Alert Signal is completed, the Si2401 applies the
wetting pulse for the required 15 ms by quickly going
off-hook and on-hook. From this point on, the algorithm
is identical to that of Bellcore in that it searches for the
channel seizure signal and the marks before echoing an
“m” and then reports the decoded caller ID data.
4.6. V.23 Operation/V.23 Reversing
The Si2401 supports full V.23 operation including the
V.23 reversing procedure. V.23 operation is enabled by
setting S07 (MF1) = xx10xx00
S07[5] (V23R) = 1, the Si2401 transmits data at 75 bps
and
S07[4] (V23T) = 1, the Si2401 receives data at 75 bps
and transmits data at 600 or 1200 bps. S07[2] (BAUD)
is the 1200 or 600 bps indicator. BAUD = 1 enables the
1200/600 V.23 channel to run at 1200 bps, while
BAUD = 0
When a V.23 connection is successfully established, the
modem responds with a “c” character if the connection
16
configuration).
type caller ID) or S13[2] (CIDB) = 1 (set modem to
UK type caller ID).
receives
b
feature,
enables 600 bps operation.
data
the
b
(set modem to 8N1
at
following
600
b
or xx01xx00
or
configuration
1200 bps.
b
. If
Rev. 1.1
is
If
is made with the modem transmitting at 1200/600 bps
and receiving at 75 bps. The modem responds with a
“v” character if a V.23 connection is established with the
modem transmitting at 75 bps and receiving at 1200/
600 bps.
The Si2401 supports the V.23 turnaround procedure.
This allows a modem that is transmitting at 75 bps to
initiate a “turnaround” procedure so that it can begin
transmitting data at 1200/600 bps and receiving data at
75 bps. The modem is defined as being in V.23 master
mode if it is transmitting at 75 bps, and it is defined as
being in slave mode if the modem is transmitting at
1200/600 bps. The following paragraphs give a detailed
description of the V.23 turnaround procedure.
4.6.1. Modem in Master Mode
To perform a direct turnaround once a modem
connection is established, the master host goes into
online command mode by sending an escape command
(Escape pin activation, TIES, or ninth bit escape) to the
master modem.
Note: The host can initiate a turnaround only if the Si2401 is
The host then sends the ATRO command to the Si2401
to initiate a V.23 turnaround and return to the online
(data) mode.
The Si2401 then changes its carrier frequency (from
390 Hz to 1300 Hz) and waits to detect a 390 Hz carrier
for 440 ms. If the modem detects more than 40 ms of a
390 Hz carrier in a time window of 440 ms, it echoes the
“c” response character. If the modem does not detect
more than 40 ms of a 390 Hz carrier in a time window of
440 ms, it hangs up and echoes the “N” (no carrier)
character as a response.
4.6.2. Modem in Slave Mode
Configure GPIO4 as INT (SE2[7:6] [GPIO4] = 11). The
Si2401 performs a reverse turnaround when it detects a
carrier drop longer than 20 ms. The Si2401 then
reverses (changes its carrier from 1300 Hz to 390 Hz)
and waits to detect a 1300 Hz carrier for 400 ms. If the
Si2401 detects more than 40 ms of a 1300 Hz carrier in
a time window of 400 ms, it sets the S09[7] bit, and the
next character echoed by the Si2401 is a “v”.
If the Si2401 does not detect more than 40 ms of the
1300 Hz carrier in a time window of 400 ms, it reverses
again and waits to detect a 390 Hz carrier for 440 ms.
Then, if the Si2401 detects more than 40 ms of a
390 Hz carrier in a time window of 220 ms, it sets the
S09[7] bit, and the next character echoed by the Si2401
is a “c”.
At this point, if the Si2401 does not detect more than
40 ms of the 390 Hz carrier in a time window of 440 ms,
it hangs up, sets the S09[7] bit, and the next character
the master.