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Rev. 1.4 11/13 Copyright © 2013 by Silicon Laboratories AN93
AN93
Si2493/57/34/15/04 (Revisions D and D1) and Si2494/39
(Revisions A and A1) Modem Designer’s Guide
1. Introduction
The Si2494/93/57/39/34/15/04 ISOmodem chipset family consists of a 38-pin QFN (Si2494/39) or 24-pin TSSOP
(Si2493/57/34/15/04) or 16-pin SOIC (Si2493/57/34/15/04) low-voltage modem device, and a 16-pin SOIC line-
side DAA device (Si3018/10) connecting directly with the telephone local loop (Tip and Ring). This modem solution
is a complete hardware (controller-based) modem that connects to a host processor through a UART, parallel or
SPI interface. Parallel and EEPROM interfaces are available only on the 38-pin QFN or 24-pin TSSOP package
option. Refer to Table 4, “ISOmodem Capabilities,” on page 10 for available part number, capability and package
combinations. Isolation is provided by Silicon Laboratories’ isolation capacitor technology, which uses high-voltage
capacitors instead of a transformer. This isolation technology complies with global telecommunications standards
including FCC, ETSI ES 203 021, JATE, and all known country-specific requirements.
Additional features include programmable ac/dc termination and ring impedance, on-hook and off-hook intrusion
detection, Caller ID, loop voltage/loop current monitoring, overcurrent detection, ring detection, and the hook-
switch function. All required program and data memory is included in the modem device. When the modem
receives a software or hardware reset, all register settings revert to the default values stored in the on-chip
program memory. The host processor interacts with the modem controller through AT commands used to change
register settings and control modem operation. Country, EMI/EMC, and safety test reports are available from
Silicon Laboratories representatives and distributors.
This application note is intended to supplement the Si2494/39 Revision A/A1, Si2493 Revision D/D1, and the
Si2457/34/15/04 Revision D/D1 data sheets. It provides all the hardware and software information necessary to
implement a variety of modem applications, including reference schematics, sample PCB layouts, AT command
and register reference, country configuration tables, programming examples and more. Particular topics of interest
can be easily located through the table of contents or the comprehensive index located at the back of this
document.
Figure 1. Functional Block Diagram
UART
Interface
Parallel
Interface
DSP
DAA
Interface
ROM
PLL
Clocking
XTI XTO
CLKOUT
INT
RESET
C1
To Phone
Line
AOUT
Data Bus
Controller
Si3018/10
RXD
TXD
CTS
RTS
DCD
ESC
RI
CS
WR
RD
A0
D0-D7
Program Bus
RAM
EEPROM
Interface
EESD
EECLK
EECS
C2
Si3000
Interface
FSYNC
SDO
SDI
MCLK
SPI
Interface
SDI
SDO
SCLK
SS
AOUTb
