SI2457-C-FT Silicon Laboratories Inc, SI2457-C-FT Datasheet - Page 31

• Manufacturer Part Number: SI2457-C-FT
• Description: IC ISOMODEM SYSTEM-SIDE 24TSSOP
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2457-C-FT

• Package / Case: 24-TSSOP
• Mfg Application Notes: SI2493/57/34/15/04, Appl Note AN93
• Data Format: V.21, V.22, V.23, V.32, V.34, V.90, Bell 103, Bell 212A
• Baud Rates: 56k
• Interface: Parallel, UART
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Operating Frequency: 4.92 MHz
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 3 V
• Supply Current: 26 mA
• Operating Temperature Range: 0 C to + 70 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

Command
%V1
%V2
Table 13. Extended AT% Command Set (Command Defaults in Bold) (Continued)
Automatic Line Status Detection—Fixed Method.
Description: Before going off-hook with the ATD, ATO, or ATA commands, the Si2457/34/15/04 com-
pares the line voltage (via LVCS) to registers NOLN (U83) and LIUS (U84):
Loop Voltage
0 ≤ LVCS ≤ NOLN
NOLN ≤ LVCS ≤ LIUS
LIUS ≤ LCVS
Once the call has begun, the off-hook intrusion algorithm (described in "4.12.2. Off-Hook Intrusion
Detection" on page 18) operates normally. In addition, the Si2457/34/15/04 will report “NO LINE” if
the telephone line is completely disconnected. If the HOI bit (U77, bit 11) is set, “LINE IN USE” is
reported upon intrusion.
Automatic Line Status Detection—Adaptive Method.
Description: Before going off-hook with the ATD, ATO, or ATA commands, the Si2457/34/15/04 com-
pares the line voltage (via LVCS) to the NLIU (U85) register:
Loop Voltage
0 ≤ LVCS ≤ (0.0625 x NLIU)
(0.0625 x NLIU) < LVCS ≤ (0.85 x NLIU)
(0.85 x NLIU) < LCVS
The NLIU register is updated every 1 ms with the minimum non-zero value of LVCS in the last
30 ms. This allows the Si2457/34/15/04 to eliminate errors due to 50/60 Hz interference and also
adapt to relatively slow change in the on-hook dc reference value on the telephone line. This algo-
rithm does not allow any non-zero values for NLIU below 0x0007. The host may also initialize NLIU
prior to issuing the %V2 command. Once the call has begun, the off-hook intrusion algorithm
(described in "4.12.2. Off-Hook Intrusion Detection" on page 18) operates normally. In addition, the
Si2457/34/15/04 will report “NO LINE” if the telephone line is completely disconnected. If the HOI
(U77, bit 11) bit is set, “LINE IN USE” is reported upon intrusion.
Action
Report “NO LINE” and remain on-hook.
Report “LINE IN USE” and remain on-hook.
Go off-hook and establish a modem connection.
Preliminary Rev. 0.7
Action
Report “NO LINE” and remain on-hook.
Report “LINE IN USE” and remain on-hook.
Go off-hook and establish a modem connection.
Action
Si2457/34/15/04-Si3008
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