SI2493-C-FT Silicon Laboratories Inc, SI2493-C-FT Datasheet - Page 186

• Manufacturer Part Number: SI2493-C-FT
• Description: 56 KBPS, V.92 ISOMODEM SYSTEM-SIDE - LEAD-FREE TSSOP 0 TO 7
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2493-C-FT

• Mfg Application Notes: SI2493/57/34/15/04, Appl Note AN93
• Data Format: V.21, V.22, V.23, V.29, V.32, V.34, V.90, V.92, Bell 103, Bell 212A
• Baud Rates: 56k
• Interface: Parallel
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AN93
A
In general, EPOS applications require nearly flawless call connection reliability and a very short overall transaction
time. The message length of a typical EPOS terminal is between 120 to 260 bytes of information. Due to the
relatively small message length and the need for reliable connections under all line conditions and short connect
times, the preferred modulations have traditionally been variations of V.22 (1200 bps) or Bell212 (1200 bps). EPOS
servers do not strictly follow ITU standards. There are no ITU "fast connect" standards in spite of the term "V.22
fast connect." De-facto standards with modifications of ITU standards, such as V.22 FastConnect, have been
adopted to reduce the transaction time. Some server manufacturers make changes to the modem with the intent of
making it difficult for competing terminals to connect. Many EPOS servers have "out-of-spec" clocks and use
reduced handshake timing. V.22bis (2400 bps) is occasionally used in EPOS terminals as well. The primary
method by which V.22bis terminals achieve a shorter connection time has been through the use of a shorter
answer tone. V.29 FastPOS is a Hypercom proprietary protocol based on the V.29 Fax standard. For these
reasons, EPOS applications sometimes require technical detective work and fine tuning of the ISOmodem
performance typically with a patch.
Recently, improvements to the overall user experience have necessitated the storage of transaction information
within the EPOS terminal based on some predefined criteria. These stored transactions are typically sent as part of
a larger transaction at a later time. This effectively increases the message length to over 2 kB, necessitating the
use of higher speed modulations, such as V.29 FastPOS or V.32bis.
The choice of either V.29 FastPOS vs. V.32bis is a trade-off between transaction message length and connection
times. It is common for a terminal to support both of these modulations.
Modulation
V.90
V.34
V.32b
V.22b
V.22
V.22FastConnect
V.29FastPOS
*Note: Does not include dial delay.
VISA II (7E1)
186
PPENDIX
Dials host
Terminal
Disconnects
STX <data>ETX, LRC
ACK (0x06)
D—EPOS A
Typical Connect Time (Sec)*
25
10.7
7.8
5.0
3.0
0.6
0.5
PPLICATIONS
Rev. 0.9
STX <data>ETX, LRC
ENQ (0x05)
ACK (0x06)
EOT (0x04)
Host