Si2493/57/34/15/04
Global ISOmodem-EVB
Evaluation Board Rev 5.0 for the Si2493/57/34/15/04
ISOmodem with UART and SPI Interfaces
Description
The global Si2493/57/34/15/04-EVB evaluation board
Rev 5.0 provides the system designer an easy way of
evaluating the Si2493/57/34/15/04 ISOmodem®. The
Si2493/57/34/15/04-EVB consists of a motherboard
with a power supply, an RS-232 and USB interface,
other ease-of-use features, and a complete removable
modem module on a daughter card. (A functional block
diagram of the Si2493/57/34/15/04-EVB is shown
below.) The Si2493/57/34/15/04 ISOmodem is a
complete controller-based modem chipset with an
integrated
and
programmable
direct
access
arrangement (DAA) that meets global telephone line
requirements. Available as a combination of one 16-pin
small line-side device and one 24-pin or 16-pin systemside device, the Si2493/57/34/15/04 ISOmodem
eliminates the need for a separate DSP data pump,
modem controller, memories, codec, isolation
transformer, relays, opto-isolators, and a 2- to 4-wire
hybrid. The Si2493/57/34/15/04 is ideal for embedded
modem applications due to its small board area,
controller-based architecture, low power consumption,
and global compliance. The Si2493/57/34/15/04-EVB
provides an RJ-11 jack (for interfacing the Si2493/57/
34/15/04-EVB to the phone line), and USB and RS232
serial ports for interfacing to a PC or data terminal. This
allows the ISOmodem to operate as a serial modem for
straightforward evaluation of the Si2493/57/34/15/04. To
evaluate the Si2493/57/34/15/04 ISOmodem in an
embedded system, the daughter card can be used
independently of or with the motherboard.
A direct access header (J103) is available on the
motherboard to bypass the RS-232 transceivers and
connect the Si2493/57/34/15/04 ISOmodem directly to
a target system.
An on-board rectifier, filter, and voltage regulator allow
the power input to be 7.5–13 V ac or dc (either polarity)
supplied through a screw terminal (J8) or a standard
2 mm power jack (J9). Alternatively, power can be
supplied through the USB interface (whether the USB or
RS232 interface is used). The evaluation board can
drive an external speaker for call monitoring or the
speaker mounted directly on the board. Please note that
the PCM interface, parallel interface, and EEPROM are
available on the 24-pin FT only. See "1.7.EVB Part
Numbers" on page 8 for ISOmodem EVB options.
Features
The Si2493/57/34/15/04-EVB includes the following:
Dual RJ-11 connection to phone line
RS-232 and USB interface to PC
Speaker for call monitoring
Direct access to Si2493/57/34/15/04 for embedded
application evaluation
Easy power connection to common 7.5 V–13.5 V
power supplies or USB port.
9 V ac adaptor
Simple installation and operation
EEPROM (24-pin FT only)
RS232 lines status display on LEDs.
Functional Block Diagram
Audio
Out
7.5-13.5 V dc or
peak ac Adaptor
Rectifier
Filter
Audio
Amplifier
Voltage
Regulator
3.3 V
Direct
Access HDR
Daughter Board Boundary
5V
USB
Connector
UART
USB I/F
DB9
RS-232
Transceivers
Interface
Selection
Jumpers
Phone
line
AOUT
Si2493/57/34/15/04
RESET XTALO
Si3018*
Interface
Circuit
RJ-11
XTALI
Push Button
Reset
Power-On
Reset
Rev. 0.7 4/11
*Si3010 for Si2404
Copyright © 2011 by Silicon Laboratories
Si2493/57/34/15/04-EVB
Si2493/57/34/15/04
1. Si2493/57/34/15/04-EVB Setup and 1.3. Motherboard and Daughter Card
Configuration
Evaluation
This section explains how to set up the Si2493/57/34/
15/04-EVB for evaluation as an RS-232 or USB
interface modem. Jumper settings, power connection,
PC/terminal connections, and terminal program
configuration settings are given. The initial modem
setup after power is applied as well as a basic tutorial
on modem operation are provided. Si2493/57/34/15/04EVB configurations for evaluating additional features
are discussed separately. See the Si2493/57/34/15 or
Si2404 data sheets and “AN93: Si2493/57/34/15/04/04
Modem Designer’s Guide” for complete details.
1.1. Si2493/57/34/15/04-EVB Quick Start—
RS-232 Interface
1. Set jumpers according to Figure 1, but change J6 to the
arrangement shown in Figure 3 if an FS ISOmodem
package is used.
2. Connect:
DB-9
to PC COM 1 (with a pass-through cable).
to phone line or CO simulator.
9 V ac adaptor (or USB cable).
3. Bring up:
RJ-11
Turn
on power to modem.
automatically adjusts modem DTE speed and
protocol.
4. Type “AT” followed by a carriage return.
Autobaud
Should
echo “AT” and then an “OK”.
The EVB consist of a motherboard that takes a plug in
daughter card. The motherboard can be configured in a
variety of ways that are explained below and are
managed via jumpers. The daughter card contains both
the modem system side and the isolated line interface
(DAA).
The daughter card comes preconfigured and functional
although the user may decide to change some
operating options such as the type of crystal used with
the modem chip or the type of control signals used, i.e.
UART vs parallel. These features must be managed by
changing strapping resistors soldered down to the
daughter card and by changing parts associated with
the crystal. These possible changes are explained
below.
1.3.1. Motherboard Configuration
Check all the jumper setting on the S2493/57/34/15/04EVB before applying power. The standard factory
setting for the modem in a 24-pin FT package are
shown in the figure below. This setup configures the
modem for RS232 serial operation with autobaud
enabled. Any standard terminal program configured to
communicate through a PC com port can be used to
communicate with the EVB.
Figure 1 shows the default motherboard setup for the
FT package daughter card as well as the functions of
connectors and jumpers.
1.2. Si2493/57/34/15/04-EVB Quick Start—
USB Interface
1. Set jumpers according to Figure 3, but change J6 to the
arrangement shown in Figure 3 if an FS ISOmodem
package is used.
2. Connect:
USB
cable to PC
to phone line or CO simulator
3. Download USB driver for your operating system from the
CD supplied with the evaluation board.
RJ-11
4. Install driver.
5. Bring up.
Reset
the modem.
automatically adjusts modem DTE speed and
Autobaud
protocol.
6. Type “AT” followed by a carriage return.
Should
2
echo “AT” and then an “OK”.
Rev. 0.7
Rev. 0.7
LEDs and test
points showing
status of all
control lines as
well as TX/RX
RS232 com
port link to
Host
RS232 vs USB
select jumper,
JP23, with
RS232 select
shown.
(Remove to
disable both
modes).
USB,
virtual com
port link to
Host (J11)
Audio Power
amp (U27)
(Daughter card versions
prior to rev. 2.0 will not fit
this motherboard.)
Modem daughter cards
mate with J101 & JP2.
Remove JP12
Jumper to shut
down audio
power amp U27
Tests points (+3.3V
and Isense) that allow
modem current o tbe
measured via the 1.0
Ohm shunt: R59.
Insert jumper in
JP34 to run at a
fixed 19.2 kBaud
rate.
Figure 1. Default Motherboard Setup
Reset
Pushbutton
Insert JP33 & JP34
jumpers to enable
EEPROM
EEPROM
(U5)
System Connector.
Allows all modem
signals to be
probed or routed
elsewhere.
J6: Jumpers for control
line configuration.
Shown set up for a 24
pin modem on DC.
Tip and ring
signals available
at these test
points.
RJ11
Tel. Line
connectors.
Speaker
Output,
JP11
AC/DC Pwr
Inputs: J8
or J9.
Call progress
Speaker, and its
jumper JP14.
Si2493/57/34/15/04
3
Si2493/57/34/15/04
1.3.1.1. RS232 vs USB vs User Provided IO
Selection
To change to USB operation simply move the RS232
selection jumper on JP23 to the USB position as
marked on the PCB and shown in Figure 1. When the
USB vs UART settings are changed the appropriate
indicator LED will light up on the EVB.
Various modem control lines can be rearranged
depending on the user preferences and the specific
modem chips used. This is done using JP6. The basic
two JP6 configurations are shown in the following
figures.
J6
If neither jumper is in place then neither serial port will
be activated and the user must provide I/O signals via
the pins on J103. This IO can be in ASYNCH SERIAL,
SPI SERIAL and Parallel Bus mode.
1.3.1.2. Autobaud Control
Autobaud is enabled with no jumper at the JP34
position. When a jumper is in place, autobaud is
disabled and the user must setup the host to run 19k2
baud in order to use the modem.
1
3
4
6
7
9
10
12
13
15
1.3.1.3. EEPROM Control
Figure 2. Default J6 Setup for 24-Pin Modem
Chips
To enable the EEPROM (U5) both jumpers JP34 and
JP35 must be in place and the modem reset.
JP35 physically connects the EEPROM chips select
line to the modem and allows the EEPROM to function
when addressed by the modem, while JP34 connects a
strapping option to the correct modem pin which is
sensed during reset and instructs the modem firmware
to use the EEPROM.
J6
1
3
4
6
7
9
10
12
13
15
1.3.1.4. Call Progress Configuration
The modem call establishment can be heard by
enabling the call progress feature via software (see
AN93) and Hardware. The hardware components
include installing JP12 which enabled the audio power
amplifier and installing JP14 to connect the on board
speaker to the power amplifier output. If an offboard
speaker is to be used then JP14 can be removed and
the alternate speaker can be connected to pins 1 and 4
of JP11. Note the this audio output is 8 and
differential so that neither output pin should be
grounded.
Figure 3. Default J6 Setup for 16-Pin Modem
Chips
The specific details of what the jumpers connect are
shown in Table 1, which is also found printed on the
underside of the EVB.
1.3.1.5. Control Line Configuration
Table 1. Routing of Control Signals with Jumper Position on J6
RS232
Signal
4
Si24xx 24-Pin
Si24xx 16-Pin
Si2401
Left
Right
Left
Right
Left
Right
DCD
DCD
SDI/EESD
DCD
NC
DCD
NC
RI
RI
FSYNCH
NC
RI
NC
RI
DTR
ESC
RI
ESC
NC
ESC
NC
RTS
RTS
SDO/
EECLK
NC
RTS
NC
GPIO1
DSR
INT
AOUT/INT
NC
INT
NC
AOUT/INT
Rev. 0.7
Si2493/57/34/15/04
1.3.2. Daughter Card Configuration
The daughter card comes configured with either a 24pin FT or 16-pin FS system side part and either 32 kHz
or 4.9152 MHz operation, and UART operation. The
daughter card can also be setup to operate with a third
clock frequency, an on board 27 MHz oscillator. To
change between these options requires component
changes on the daughter card.
The daughter card can also operate in three possible
interface modes: parallel bus mode, in SPI mode as well
as the default UART mode.
There are six small (0402) strapping resistors (R101 to
R106) that are on the daughter card and are configured
differently depending on the combination of chip
package, clock frequency chosen, and interface mode.
See Figures 5 and 6 for details.
The card and its options are shown in Figure 4, which
shows the Modem Daughter card Rev 2.0 top and
bottom views with the critical parts that may be changed
to select another command mode (i.e. SPI) or an
alternate crystal frequency, such as 4.9152 MHz.
Rev. 0.7
5
Si2493/57/34/15/04
Three possible crystals or ext oscillator.
These option strapping resistors select
modem command mode UART, SPI or
Parallel and crystal clock frequency.
Crystal loading caps (C40 & C41)
specific to the crystal type used.
TOP VIEW
BOTTOM VIEW
Figure 4. Modem Daughter Card Rev 2.0 Top and Bottom Views
Figure 5. R101–R106 Setup for Clock and Mode Configuration on the DC with the 16-Pin FS
Package
6
Rev. 0.7
Si2493/57/34/15/04
Figure 6. R106 Setup for Clock and Mode Configuration on DC with 24-Pin FT Package
1.3.2.1. 32 kHz Setup
Table 2. Signal Usage
For 32 kHz, populate Y1 with the 32 kHZ crystal shown
in the BOM and use 18 pF capacitors for the C40/C41
values. Also remove Y3 and Y1b if present and strap
R101 to R106 as shown in Figure 5.
SPI Function
JP23 Pin Number
Legacy Pin
Function
SPI_CSb
5
RTSb
The modem should then work as expected; no changes
are needed on the motherboard
SPI_MISO
7
RXD
SPI_MOSI
9
TXD
SPI_SCLK
11
CTSb
1.3.2.2. 4.9152 MHz
For 4.9152 MHz, populate Y1b with the 4.9152 MHz
crystal shown in the BOM and use 33 pF capacitors for
the C40 and C41 values. Also remove Y3 and Y1 if
present and strap R101 to R106 as shown in Figures 5
or 6 above.The modem should then work as expected;
no changes are needed on the motherboard
1.3.2.3. 27 MHz
For 27 MHz, populate Y3 with the small surface mount
oscillator shown in the BOM and remove Y3 and Y1b if
present. Also remove any capacitors at the C40 and
C41 positions.
Strap R101 to R106 as shown in Figures 5 or 6 above.
The modem should then work as expected; no changes
are needed on the motherboard
1.3.2.4. SPI Mode Setup
To change to SPI mode setup it is necessary to
configure the R101 straps as shown in Figure 5 or
Figure 6, according to the package and clock used.
Then setup the daughter card with neither UART nor
USB operation selected, i.e. with no jumper on JP23.
The SPI signals can then be obtained on J103, the
system connector and connected to the host. Signal
usage is described in Table 2.
1.3.3. Parallel Bus Mode Setup
To change to parallel bus mode setup it is necessary to
configure the R101 straps as shown in Figure 5 or
Figure 6, according to the package and clock used.
Then setup the daughter card with neither UART nor
USB operation selected, i.e. with no jumper on JP23.
The SPI signals can then be obtained on J103, the
system connector and connected to the host. See the
data sheet and schematic for signal and pin usage.
1.4. Power Requirements
The Si2493/57/34/15/04-EVB has an on-board diode
bridge, filter capacitor, and voltage regulator (U10 and
U18). Power can be supplied from any source capable
of providing 7.5 V–13 V dc or 7.5 V–13 V peak ac and
at least 100 mA. (Additional current may be required if a
speaker is connected for monitoring call progress
tones.) Power may be applied to the Si2493/57/34/15/
04-EVB through the screw terminals (J8), the 2 mm
power jack (J9), or the USB cable (even if the modem is
configured for RS-232 operation). The onboard fullwave rectifier and filter ensure the correct polarity is
applied to the Si2493/57/34/15/04-EVB. Daughter card
current can be measured by connecting a DVM across
R59, a 1 resistor using the supplied test points on
Rev. 0.7
7
Si2493/57/34/15/04
the data mode. After the ATO command, the modem
resumes the data connection and no longer accepts AT
commands.
either side.
1.5. Terminal and Line Connections
The Si2493/57/34/15/04 can be tested as a standard
serial data modem by connecting the Si2493/57/34/15/
04-EVB to a personal computer or other data terminal
equipment (DTE), phone line, and power. Connect a PC
serial port to the DB9 connector on the Si2493/57/34/
15/04-EVB with a pass-through cable. The RS-232
transceivers on the EVB can communicate with the DTE
at rates up to 1 Mbps. Any standard terminal program,
such as HyperTerminal or ProComm, running on a PC
communicates with the Si2493/57/34/15/04-EVB. The
standard factory jumper configuration has autobaud
enabled. Autobaud detects the DTE speed, data length,
parity, and number of stop bits.
If JP33 is installed, autobaud is disabled. Configure the
terminal emulation program to 19200 bps, eight data
bits, no parity, one stop bit, and hardware (CTS)
handshaking. Connect the RJ-11 jack on the Si2493/57/
34/15/04-EVB to an analog phone line or telephone line
simulator, such as a Teltone TLS 5.
1.6. Making Connections
With the terminal program properly configured and
running, apply power to the Si2493/57/34/15/04-EVB.
Type “AT”, and the modem should return “OK”
indicating the modem is working in the command mode
and communicating with the terminal. If the “OK”
response is not received, try resetting the modem by
pressing the manual reset switch (S1); then, again type
“AT.” Next, type “ATI6.” The modem should
respond with “2493”, “2457”, “2434”, “2415”, or “2404”
indicating the terminal is communicating with an Si2493,
Si2457, Si2434, Si2415, or Si2404.
Type “ATS0=2” to configure the modem to answer
on the second ring.
To take the modem off-hook, type “ATH1.” The
modem should go to the off-hook state, draw loop
current, and respond with an “OK.” Next, type
“ATH” or “ATH0”, and the modem should hang
up (go on-hook) and stop drawing loop current.
To make a modem connection, type “ATDT(called
modem phone number).” Once the connection is
established, a “CONNECT” message appears indicating
the two modems are in the data mode and
communicating. Typing on one terminal should appear
on the other terminal. To return to the command mode
without interrupting the connection between the two
modems, type “+++.” Approximately two seconds later,
“OK” appears. The modem is now in command mode
and accepts “AT” commands.Type “ATH” (or “ATH0”) to
terminate the data connection, or type “ATO” to return to
8
1.7. EVB Part Numbers
The ISOmodem evaluation boards are offered in
multiple speeds and packaging options. The first four
numbers indicate the system-side device. The next two
letters indicate the system-side package (FS–Lead-free,
16-pin SOIC; FT–Lead-free, 24-pin TSSOP). The final
two numbers indicate the line-side device. See Figure 7.
Si2457-D-FS18-EVB
LS Part Number (Si30xx)
SS Package
SS Revision
SS Part Number
Figure 7. EVB Part Number Example
2. Si2493/57/34/15/04-EVB
Functional Description
The Si2493/57/34/15/04-EVB is a multipurpose
evaluation system. The modem daughter card
illustrates the small size and few components required
to implement an entire controller-based modem with
global compatibility. The daughter card can be used
independently of, or in conjunction with, the
motherboard. The motherboard adds features that
enhance the ease of evaluating the many capabilities of
the Si2493/57/34/15/04 ISOmodem®.
2.1. Motherboard
The motherboard provides a convenient interface to the
Si2493/57/34/15/04 DC (daughter card). The versatile
power supply allows for a wide range of ac and dc
voltages to power the board. RS-232 transceivers and a
DB9 connector allow the Si2493/57/34/15/04-EVB to be
easily connected to a PC or other terminal device.
Jumper options allow direct access to the LVCMOS/TTL
level serial inputs to the Si2493/57/34/15/04, bypassing
the RS-232 transceivers or USB interface. This is
particularly useful for directly connecting the Si2493/57/
34/15/04 to embedded systems.
The Si24xxURT-EVB motherboard connects to the
daughter card through two connectors, JP101 and JP2.
JP101 is an 8x2 header providing connection to all
Si2493/57/34/15/04 digital signals and regulated 3.3 V
power for the Si2493/57/34/15/04. The Si2493/57/34/
15/04 digital signals appearing at JP101 (daughter card
interface) are LVCMOS and TTL compatible. JP2 is a
4x1 socket providing connection between the daughter
Rev. 0.7
Si2493/57/34/15/04
card and the RJ-11 phone jack.
2.1.5. EEPROM Enable (FT Only)
2.1.1. Voltage Regulator/Power Supply
Connecting JP34 and JP35 enables the optional
EEPROM, U5. See “AN93: Si2457/Si2434/Si2415/
Si2404 Modem Designer’s Guide” for programming
details.
The input voltage to either J8 or J9 must be between 7.5
and 13.5 V dc or 7.5 and 13.5 VPEAK ac. The
motherboard includes a diode bridge (D12) to guard
against a polarity reversal of the dc voltage or to rectify
an ac voltage. The power source must be capable of
continuously supplying at least 100 mA. C44 serves as
a filter cap for an ac input. The voltage regulator, U10,
provides 5 V for the motherboard and the input for
voltage regulator U3, which outputs 3.3 V for use on the
motherboard and to power the daughter card. Si24xxDC
power consumption can be measured by placing a
meter across R59. Power is supplied to U2 through D5
from the USB.
2.1.2. Reset Circuitry
The Si2493/57/34/15/04 requires a reset pulse to
remain low for at least 5.0 ms after the power supply
has stabilized during the powerup sequence or for at
least 5.0 ms during a power-on reset. Most production
Si2493/57/34/15/04 modem chipset applications require
that RESET be controlled by the host processor. Certain
Si2493/57/34/15/04
operation
modes,
including
powerdown, require a hardware reset to recover.
The Si2493/57/34/15/04-EVB contains two reset
options, an automatic power-on reset device, U18
(DS1818) (default), and a manual reset switch (S1) to
permit resetting the chip without removing power. A
reset, regardless of the mechanism, causes all modem
settings to revert to factory default values.
2.1.3. Automatic Reset (DS1818)
The DS1818 is a small, low-cost device that monitors
the voltage on VD and an external reset pushbutton. If
VD drops below 3.0 V, the DS1818 provides a 220 ms
active-low reset pulse. On powerup, the DS1818 also
outputs an active low reset pulse for 220 ms after VD
reaches 90% of the nominal 3.3 V value. The DS1818
outputs a 220 ms reset pulse any time the power supply
voltage exceeds the 3.3 V ±10% window.
2.1.6. Interface Selection
The serial interface of the Si2493/57/34/15/04-EVB can
be connected to a computer, terminal, embedded
system, or any other data terminal equipment (DTE) via
a standard RS-232 interface, USB interface, or through
a direct TTL serial interface.
The Si2493/57/34/15/04 can be tested as a standard
data modem by connecting the Si2493/57/34/15/04EVB to a personal computer or other DTE power supply
and a phone line. A PC can communicate with the
Si2493/57/34/15/04-EVB using a standard terminal
program, such as HyperTerm or ProComm.
Jumper settings determine how the Si2493/57/34/15/
04-EVB is connected to the DTE.
2.1.7. RS-232 Interface
This operation mode uses the standard factory jumper
settings illustrated in Figure 1 on page 3. The Maxim
MAX3237 transceiver interfaces directly with the TTL
levels available at the serial interface of the Si2493/57/
34/15/04 and, using internal charge pumps, makes
these signals compatible with the RS-232 standard. The
RS-232 transceiver on the Si2493/57/34/15/04-EVB can
communicate at rates between 300 bps and 1 Mbps.
This simplifies the connection to PCs and other data
terminal equipment (DTE). The signals available on the
Si2493/57/34/15/04-EVB
serial
interface
(DB9
connector) are listed in Table 3.
2.1.8. USB Interface
The USB cable connects to J10 on the motherboard
and provides both data and power. Installing a jumper
on JP23 enables the USB interface and disables the
RS-232 interface. The USB interface is provided by
U12. A USB driver for this chip is available for most PC
and MAC operating systems on the CD.
2.1.4. Manual Reset
The manual reset switch (S1) performs a power-on
reset. This resets the Si2493/57/34/15/04 to factory
defaults without turning off power. Pressing S1 activates
the reset monitor in the DS1818 and produces a 220 ms
active low reset pulse.
Rev. 0.7
9
Si2493/57/34/15/04
operation of the modem. See “AN93: Si3457/34/15/04
Modem Designer’s Guide” for more details on the
features controlled by pin strapping.
2.1.9. Direct Access Interface
While the motherboard supplies power through J8, J9,
or USB, power-on reset, and an RJ–11 jack for the
modem, the direct access interface (J103) is used to
connect the motherboard to an embedded system. J103
provides access to all Si2493/57/34/15/04 signals
available on the daughter card.
Since this PWM signal swings rail to rail and is simply
filtered by a low pass filter to acquire the audio. It is
important to keep the power supply to the modem free
of noise in the audio spectrum.
2.1.11.2. The Audio Output Amplifier (LM4819)
It is necessary to remove the jumper on JP23 to disable
both the RS-232 and USB interface and prevent signal
contention.
The Power amplifier on the EVB is powered by a current
limited 4.2 V supply. The current limit is implemented in
the EVB because it is intended for HW/SW
development and is not needed for a production design.
This amplifier can drive an 8 speaker with 200 mW of
Call progress audio (i.e., ISOmodem's call progress
dialing and negotiation tones).
2.1.10. PCM Interface (24-Pin FT Only)
The Si2493/57/34/15/04 PCM interface can be
demonstrated using the voice motherboard, not with this
EVB.
2.1.11. AOUT Call Progress Audio Output
The power amplifier itself is a low cost, rugged H bridge
type device. There are several pin compatible designs
from multiple vendors that can provide alternate price/
power tradeoffs for this amplifier. This power amp can
be shut down by removing jumper JP12. The signal at
JP12 can also be tied to a control signal to allow the
host to shut down the amplifier. The customer can
change the values of R172 and R173 when integrating
the EVB to his system, but should keep the RC formed
by C37 and R173 at a 50 Hz or higher corner to avoid a
power-on thump.
Call progress audio output is provided by the Si2493/57/
34/15/04 on the AOUT pin as a PWM signal. This signal
allows the user to monitor call progress signals, such as
dial tone, DTMF dialing, ring, busy signals, and modem
negotiation. Control of this signal is provided by AT
commands and register settings described in the
introduction. The AOUT signal is connected to an on
board amplifier, for a high-quality output. AOUT can
also be connected to a summing amplifier or multiplexer
in an embedded application as part of an integrated
audio system.
2.1.11.3. The Call Progress Speaker
2.1.11.1. AOUT Audio Processing
The Call progress speaker, Regal RE-2308-NL is
connected to the amplifier via a jumper, JP14. If another
speaker is to be connected then it is necessary to
remove JP14 and connect the external speaker to JP11,
Pins 1 and 4. It is important to remember that the
speaker signal is differential. Both the output pins are
driven outputs and must not be grounded.
The AOUT signal discussed in this section leaves the
Si2493/57/34/15/04 is processed (demodulated) by a
high pass filter: (R133,134,135, and C24, C25, 26,
C27). It is critically important to not put a dc load on the
AOUT pin since the pin also acts as a modem feature
control on reset and is internally weakly pulled up. Any
unintentional dc load on AOUT prevents proper
Table 3. DB9 Pin Connections
J1 Name
J1 Symbol
J1 Pin
Carrier Detect
CD
1*
See note
DCD/EESD
Received Data
RXD
2
9
RXD
Transmit Data
TXD
3
10
TXD
Data Terminal Ready
DTR
4*
See note
ESC/RI
SG
5
6
GND
Data Set Ready
DSR
6*
See note
INT/AOUT
Ready to Send
RTS
7*
See note
RTS/RXCLK
Clear to Send
CTS
8
11
CTS
*
17
RI
Signal Ground
Ring Indicator
RD
9
*Note: JP6 jumper option.
10
Rev. 0.7
Si2493/57/34/15/ Si2493/57/34/15/
04 Pin
04 Name
Si2493/57/34/15/04
2.2. Modem Daughter Card Operation
The Si2493/57/34/15/04URT-EVB daughter card is a
complete modem solution perfectly suited for use in an
embedded system. The daughtercard contains both the
modem system-side chip and the isolated line interface
(DAA).
The daughter card requires a 3.3 V supply capable of
providing at least 35 mA and communicates with the
system via LVCMOS/TTL-compatible digital signals on
JP1. The RJ-11 jack (TIP and RING) is connected via
JP2. Be sure to provide the proper power-on reset pulse
to the daughter card if it is used in the stand-alone
mode.
2.2.1. Reset Requirements
The Si2493/57/34/15/04 ISOmodem® daughter card
must be properly reset at powerup. The reset pin (pin 8)
of the Si2493/57/34/15/04 (JP103, J101 pin 13) must be
held low for at least 5.0 ms after power is applied and
stabilized to ensure the device is properly reset.
2.2.2. Crystal Requirements
Clock accuracy and stability are important in modem
applications. To ensure reliable communication between
modems, the clock must remain within ±100 ppm of the
design value over the life of the modem. The crystal
selected for use in a modem application must have a
frequency tolerance of less than ±100 ppm for the
combination of initial frequency tolerance, drift over the
normal operating temperature range, and five year
aging. Other considerations, such as production
variations in PC board capacitance and the tolerance of
loading capacitors, must also be taken into account.
2.2.3. Protection
The Si2493/57/34/15/04-EVB meets or exceeds all FCC
and
international
PTT
requirements
and
recommendations for high-voltage surge and isolation
testing without any modification. The protection/isolation
circuitry includes C1, C2, C8, C9, FB1, FB2, and RV1.
The PCB layout is also a key “component” in the
protection circuitry. The Si2493/57/34/15/04-EVB
provides isolation to 3 kV. Contact Silicon Laboratories
for information about designing to higher levels of
isolation.
Rev. 0.7
11
RTSb
CTSb
AOUT_INTb
FSYNCH
INTb
RIb
DCDb
12
8
9
10
11
U12
R101
R102
R103
R104
R105
R106
Rev. 0.7
No
No
Yes
Yes
No
No
Yes
No
No
No
Yes
Yes
No
Yes
No
No
No
No
Yes
X
X
Yes
No
Yes
SPI 4.9252 MHz
UART 32 kHz
SPI 27 MHz
SPI 32 kHz
2
OUT
VCC
3
4
VDD
C55
0.1uF
X
X
No
No
No
Yes
Yes
Yes
No
No
X
X
No
No
X
X
Yes
No
X
X
Yes
Yes
Yes
No
Pin17 Pin23
RIb
DCDb
R105 R106
32.768 kHz
4.9152 MHz
27 Mhz
Parallel 4.9152 MHz
Parallel 27 Mhz
UART 27 Mhz
UART 4.9152 MHz
UART 32.768 kHz
SPI
SPI
SPI
8
XTALI
VDD
C54
1uF
R18
FB5
U13
Si24xx-16 pin
33pF
RIb
R120
9
10
NI
NI
1
3
5
7
9
11
13
15
1
3
5
7
9
11
13
15
2
4
6
8
10
12
14
16
2
4
6
8
10
12
14
16
SOCKET 8x2
J1
ESC
SDI_EESD
RIb
INTb
AOUT_INTb
SDO_EECLK_RTSb
DCDb
These components are for
internal Silabs use only.
C2A
C1A
XTALO
2
SDI_EESD R121
C2A
C1A
XTALO
XTALI
C52
0.1uF
1
C50
0.1uF
CLKIN/XTALI
CLKOUT_EECSb_AO
FSYNCH
RTSb
RXD
R110
200
TXD
R111
200
CTSb
R112
200
RESETb
C40
C41
33pF
RESET
C56
0.1uF
1.2K
VDD
RTSb_SPI_CSb
RXD_SPI_MISO
TXD_SPI_MOSI
CTSb_SPI_SCLK
DCDb
ESC
RIb
INTb
VA
Y1B
Y1
32.768KHz 4.9152MHz
XTALO
RESETb
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