SI2457-C-FT Silicon Laboratories Inc, SI2457-C-FT Datasheet - Page 20

• 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

Si2457/34/15/04-Si3008
4.13. Overcurrent Detection
The Si2457/34/15/04 includes an overcurrent detection
feature
programmable time after the Si2457/34/15/04 goes off-
hook. This allows the Si2457/34/15/04 to detect if it is
connected to an improper telephone line. The
overcurrent detection feature may be enabled by setting
the OCDM bit (U70, bit 11). OHT (U77, bits 8:0) sets the
delay after off-hook until the loop current is measured.
See “AN93: Modem Designer’s Guide” for details.
4.14. Firmware Upgrades
The Si2457/34/15/04 contains an on-chip program ROM
that includes the firmware required for the features
listed in this data sheet. In addition, the Si2457/34/15/04
contains on-chip program RAM to accommodate minor
changes to the ROM firmware. This allows Silicon Labs
to provide future firmware updates to optimize the
characteristics of new modem designs and those
already deployed in the field. See “AN93: Modem
Designer’s Guide” for complete details.
4.15. SMS / MMS Support
The Si2457/34/15/04 supports V.23 half-duplex. This
modulation provides the low-level functionality needed
for SMS and MMS protocols. See “AN93: Modem
Designer’s Guide” for complete details.
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that
measures
the
loop
current
Preliminary Rev. 0.7
at
a
4.16. Codec Interface (24-Pin Version Only)
In order to support a full range of voice and data
applications, the Si2457/34/15/04 includes an optional
serial interface that connects to an external voice codec
(Si3000). See “AN93: Modem Designer’s Guide” for
complete details.
4.17. EEPROM Interface
The Si2457/34/15/04 supports an optional serial
peripheral interface (SPI) bus serial EEPROM Mode 3
with a 16-bit (8–64 kbit range) address. Upon powerup,
if a pulldown resistor ≤10 kΩ is placed between D6
(Si2457, pin 4) and GND (see Table 9), the ISOmodem
attempts to detect an EEPROM. The EEPROM is
intended first for setting custom defaults, second for
automatically loading firmware upgrades, and third to
allow for user-defined AT command macros for use in
custom AT commands or country codes. See “AN93:
Modem Designer’s Guide” for complete details.
4.18. AT Commands
At powerup, the Si2457/34/15/04 is in the AT command
mode. In command mode, the modem monitors the
input (serial or parallel) checking constantly for a valid
command (AT commands are described in Table 11.)
(24-Pin Version Only)