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xecom
XE2476
3-8-94
2400 bps Plug-In Upgrade to CH1776
Description
Xecom's XE2476 is a low cost, 2400 bit per
second plug-in upgrade to the 1200 bps
CH1776. The XE2476 features the same
pin configuration, lead spacing and case size
as the CH1776. It also includes its own
user transferable FCC Part 68 registration.
Industry standard "AT" commands provide
modem control and configuration. The
XE2476 was specifically designed to provide
users of the CH1776 a quick, easy and low
cost upgrade to 2400 bits per second. Most
OEM's currently using the CH1776 can use
the XE2476 to upgrade their systems from
1200 bps to 2400 bps without alterring the
existing design.
Block Diagram
Features
• Supported Protocols: V.22bis, V.22, V.21,
Bell 212A and 103
• Pin compatible with the 1200bps CH1776
• Command set: "AT" command set for
modem control and configuration.
• Identical physical dimensions to CH1776:
2.00 inches long, 1.125 inches wide, 0.44
inches high.
• Single +5V supply
• Low power CMOS:
Operating: 250 mW (Typ.)
Sleep mode: 50 mW (Typ.)
PIN CONFIGURATION
/HS
/CMD
/AAD
/DCD
/DTR
D/V
OHO
RXD
TXD
TEST
SPK
VO
VI
1 18
2 17
3 16
4
5
6
XE2476
7
(Top View)
8
9
10
11
12
13
RI
GND
VCC
15
14
RING
TIP
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XE2476 Mechanical Specifications
INCHES METRIC(MM)
PIN MIN MAX MIN MAX
A 1.990 2.010 50.55 51.05
B 1.115 1.135 28.32 28.83
C 0.420 0.430 10.67 10.92
D 0.100 0.120 2.54 3.05
E 0.890 0.910 22.61 23.11
F 0.090 0.110 2.29 2.79
G 0.090 0.110 2.29 2.79
H 0.190 0.210 4.83 5.33
I 0.020 0.025 0.51 0.64
J 0.125 0.200 3.18 5.08
Pins = Ø0.025 square pin
All pins tin-plated
Pin Descriptions
PIN NAME I/O DESCRIPTION
1 \HS O High Speed indicator, output, active LO, TTL/CMOS. Low when
operating at 2400bps rate, high otherwise.
2 \CMD - Command Enable is not supported on the XE2476. This pin is open
internally.
3 \AAD - The Automatic Answer Disable pin is not supported in the XE2476.
Register S0 controls automatic answer operation.
4 \DCD O The operation of Data Carrier Detect is controlled by the &C command.
DCD may be configured to remain active, DCD low, or may go low to
indicate receipt of valid carrier.
5 \DTR I Data Terminal Ready is an active low input The function of this pin is
set by the &D command and the value in register S21. Normally, the
modem ignores DTR.
2/XECOM XE2476
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PIN NAME I/O DESCRIPTION
6 D/V O The Data/Voice output can be used to drive a relay to connect an
auxiliary telephone handset. Data/Voice is high when the modem is offhook.
7 OH O Off-hook is an active high output which indicates that the XE2476 is
connected to the telephone line.
8 RXD O Received Data provides the serial data output from the modem. A logic
"high" represents a "mark" and a logic "low" represents a "space".
9 TXD I Transmit data provides the serial data input from the host. A logic
"high" represents a "mark" and a low represents a"space", TTL.
10 Test - The Test pin should be left unconnected at all times.
11 SPK O Audio output to the speaker. Function is determined by L & M
commands . This output cannot directly drive a low impedence
speaker. It can drive a 50k ohm load.
12 VO O The Modem Line Interface permits placement of non-modem signals on
the telephone line through the modem's telephone interface. VO must
be tied to VI for normal modem operation and open to place non-
modem signals on the line through VI.
13 VI I Voice Interface provides a path for non-modem signals to be placed on
the telephone line through the modem's telephone interface. VI must
be tied to VO for modem operation. Non-modem signals are placed on
VO to be placed on the telephone line.
14 TIP — Tip connection to the phone line(RJ11 pin3) from the internal DAA.
15 RING — Ring connection to the phone line(RJ11 pin4) from the internal DAA.
Caution: Observe design rules for Tip & Ring trace layout
16 Vcc — +5 Volt power for the modem.
17 GND — Ground reference for the modem.
18 RI O Ring Indicator provides an active high output whenever a ring signal
appears on the telephone line.
XE2476 XECOM\3
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AT Commands
The XE2476 uses "AT" commands for configuration and control. This section describes use
of the AT command format and lists the AT commands, Registers and Result codes used.
Modes of Operation
The "AT" commands have two operational modes; Command Mode and Data Mode.
Data Mode: The XE2476 enters data mode after it connects with a remote modem and
issues an appropriate "CONNECT" result code. In the Data Mode the modem sends all data
presented on Transmit Data (TXD) to the remote modem and puts data from the remote
modem onto Received Data (RXD). When the modem exits data mode, it issues a "NO
CARRIER" result code.
Command Mode: The XE2476 enters command mode on power-up, reset, a lost
connection, or receipt of the escape code. In command mode the modem accepts
commands from the host on transmit data. Appropriate result codes are returned on
received data.
Command Line Format
Command lines issued to the modem follow a strict format. Each command begins with the
prefix AT. The command line is stored in the command buffer and executed upon receipt of
a carriage return. Until executed, the command line can be editied with the backspace key.
Command Prefix - Each command, except the A/ command, begins with the AT prefix. The
"A" and "T" may be either both upper case or both lower case but cannot be of different
cases. The prefix identifies the speed and parity of the commands sent to the modem by the
host. Speed is determined by measuring the width of the incoming bits. Parity is determined
by comparing the parity bit of the "A" and the "T."
Command Line - Commands may be strung together in a single command line of up to 40
characters. Commands are executed in the sequence they appear. Spaces may be inserted
into the command line but do not fill space in the command buffer. A carriage return
terminates the command line and causes the commands to be executed. Register S3 allows
the user to select a character other than a carriage return to terminate the command line.
Command Buffer - No more than 40 characters, including the AT prefix, may be loaded into
the command buffer. If the command buffer overflows, the modem issues an "ERROR"
result code and commands are not executed.
4/XECOM XE2476
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Command Line Editing - The backspace can be used to edit a command line before it is
executed. The backspace key, (Control and H simultaneously on some systems), erases
the previous character in the command line. Register S5 allows the user to select a
character other than a backspace to edit the command line.
Re-Execute Last Command - The A/ command causes the modem to reexecute the last
command line. This is the only command which does not require the "AT" prefix.
Ommitted Parameters - Most commands include a parameter which determines how the
functions will be set. When the command parameter is omitted from the command string, it
is assumed to be a 0.
Escape Characters - A 3 character escape sequence maybe entered while in data mode to
switch the modem into command mode while on line. The escape character, set by Register
S2, must be entered 3 times in succession within a 1 second guard time to execute the
escape. The default escape sequence is "+++."
Result Codes - The modem issues a result code after each action. Result codes may be
provided as full words, numeric codes or may be disabled all together. Each result code
ends with a carriage return when numeric resul codes are chosen. When full word result
AT Command List
An asterisk indicates the factory default
A - Answer Command -
Bn - Select Communications Standard
n=0 Selects CCITT standards
n=1 Selects Bell standards*
D - Dial Command -
P = Pulse dial
T = Tone dial
R = Connect as an answering modem
W = Wait for dial tone
, = Pause for the duration of S8
@ = Wait for silence
! = Switch hook flash
; = Return to the command state
En - Command Echo
n=0 Do not echo commands
n=1 Enable command echo*
Hn - Switch Hook Control -
n=0 Switch hook relay closes*
n=1 The switch hook relay opens
In - Modem Identification
Ln - Speaker Volume -
n=0 Low speaker volume
n=1 Low speaker volume
n=2 Moderate speaker volume*
n=3 High speaker volume
XE2476 XECOM\5
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AT Command List (continued)
Mn - Speaker Activity -
n=0 Speaker off
n=1 Speaker on until carrier received*
n=2 Speaker remains on
n=3 Speaker on after dialing until carrier
is detected.
On - On Line
n=0 Return On Line with no retrain*
n=1 Initiate retrain while returning On
line.
Qn - Responses
n=0 Send responses *
n=1 No Responses
Sr? - Interogate Register Sr=n - Set Register Value -
Vn - Result Codes -
n=0 Numeric Result Codes
n=1 English Word Result Codes*
Xn - Result Code Set -
n=0 Responses 0-4*
n=1 Responses 0-5 & 10
n=2 Responses 0-6 & 10
n=3 Responses 0-5, 7 & 10
n=4 Responses 0-7 & 10
Z - Reset -
&Cn - DCD Operation
n=0 DCD is forced active*
n=1 DCD indicates a valid carrier signal
&Dn - DTR
n=0 DTR is ignored by the modem*
n=2 Modem disconnects if the host
revokes DTR.
n=3 The modem performs a soft reset
when DTR is revoked.
&F - Revert to Factory Defaults
&Ln - Line Type
n=0 Modem operates on dial-up lines*
n=1 Modem operates on leased lines
&Qn - Communications Format
n=0 Sets the modem for normal,
unbuffered operation.
&Tn - Test Modes
n=0 Exit test mode
n=1 Local analog loopback
n=3 Initiate local digital loopback
n=4 Respond to remote loop request*
n=5 Deny remote loop request
n=6 Intiate a Remote Digital loopback
n=7 Remote digital loopback w self-test
n=8 Local analog loopback w self-test
&V - View Active Profile &Wn - Store Profile -
n=0 Stores the current configuration in
memory location 0.
n=1 Stores the current configuration in
memory location 1.
&Yn - Recall Profile
n=0 Use memory location 0.
n=1 Use memory location 1.
&Zn=X- Store Number
6/XECOM XE2476
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S-Register Summary
REG. RANGE/UNITS DESCRIPTION DEFAULT
S0 0-255/rings Number of rings to answer on 000
S1 0-255/rings Count number of incoming rings 000
S2 0-127/ASCII Escape character 043
S3 0-127/ASCII Carriage return character 013
S4 0-127/ASCII Line feed character 010
S5 0-32,127/ASCII Backspace character 008
S6 2-255/sec Dial tone wait time 002
S7 1-60/sec Wait time for remote carrier 030
S8 0-255/sec Comma pause time 002
S9 1-255/0.1 sec Carrier detect response time 006
S10 1-255/0.1 sec Delay from loss of carrier to hang up 014
S14 Bit Mapped E,Q,V,T,P,D,A,R accept/ignore 170
S16 Bit Mapped Modem loopback tests 000
S18 0-255/sec Modem test timer 000
S21 Bit Mapped J, &R, &D, &C, &S, Y 000
S22 Bit Mapped L, M, X, &P, &T4, &T5, DTE speed and parity 118
S23 Bit Mapped &T4,&T5, DTE speed, parity 007
S27 Bit Mapped &Q, &L, &X, B commands 064
Result Code Summary
DIGIT CODE WORD CODE MEANING
0 OK Successfully executed command line
1 CONNECT 300 bps connection established
2 RING Ring signal detected
3 NO CARRIER Carrier not detected within Register S7 detect time
4 ERROR Error found in command line; returns to command line
5 CONNECT 1200 1200 bps connection established
6 NO DIAL TONE No dial tone detected within 5 Sec. after going off-hook
7 BUSY Busy signal detected after automatically dialing a call
8 NO ANSWER Five seconds of silence was not detected when using the @
command in the Dial command line
10 CONNECT 2400 Connection established at 2400 bps
XE2476 XECOM\7
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Electrical Specifications
ABSOLUTE MAXIMUM RATINGS*
SUPPLY VOLTAGE - Vcc +6.5 Volts
DC INPUT VOLTAGE -0.6 Volts to +6.5 Volts
STORAGE TEMPERATURE RANGE -25° C TO +100° C
LEAD TEMPERATURE (Soldering, 2 sec per wave) 260° C
OPERATING TEMPERATURE RANGE 0 TO 70° C
*Exceeding these values may result in permanent damage to the device.
Power Supply Characteristics(TA = 0 - 70°C, Vcc = 5v ±5%)
Symbol Parameter Min Typ Max Units Comments
Vcc Supply Voltage 4.75 5.0 5.25 V
Icc Vcc Supply Current 40 mA All outputs Disconnected
Iccpd Power Down Current 10 mA
Power Management:
no activity is detected on the RXD, DTR, or RI lines the modem will, within 5 seconds, automatically go
into a smart power down mode. In this mode power consumption is typically less than 50 milliwatts.
The XE2476 has an integrated, advanced power management capability. If
I/O Characteristics
Signals Description
DIGITAL INPUTS Input High Input Low
/DTR, /RTS, TXD, RESET min. 2.0 V max. 0.8 V
DIGITAL OUTPUTS Output High Output Low Current Drive
OH, RI min. 2.4 V max. 0.8 V 15 ma
/DCD, RXD min. 2.4 V max. 0.4 V 1.6 ma
8/XECOM XE2476
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Other Performance Specifications
PARAMETER MIN TYP MAX UNIT COMMENTS
DTMF Level -2.2 0 dBm
DTMF Twist (Balance) 3 dB
DTMF Tone Duration 70 ms
Pulse Dialing Rate 10 pps
Pulse Dialing Make/Break 39/61 % USA
33/67 % CCITT
Pulse Interdigit Interval 785 ms
Billing Delay Interval 2.0 sec.
Guard Tone Frequency 550 Hz Referenced to high
Amplitude -3 dB channel transmit
Frequency 1800 Hz
Amplitude -6 dB
High Channel Transmit Amplitude -1 dB Ref. to low channel
guard tone on
Tone Detection Bandpass Frequency 290 665 Hz 3 dB point
Tone Detection OFF to ON Threshold -33 dBm into 600 ohms
Tone Detection ON to OFF Threshold -35 dBm into 600 ohms
Dial Tone Detect Duration 3.0 sec.
Ringback Tone Detect Duration 0.75 sec.
Cadence 1.5 sec. OFF/ON Ratio
Busy Tone Detect Duration 0.2 sec.
Cadence 0.67 1.5 sec. OFF/ON Ratio
PARAMETER MIN TYP MAX UNIT
Telephone Line Impedance Match 600 ohms
Ring Detect Sensitivity 38 Vrms
(on hook, Type B ringer)
Telephone Line Holding Current 20 100 mA
XE2476 XECOM/9
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Modem Applications Schematic
XECOM\10 XE2476
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FCC Instructions
This product complies with part 68 of the FCC Rules and Regulations. With each device shipped, there
is a label which contains, among other information, the FCC Registration Number and Ringer
Equivalence Number (REN) for this product. You must, upon request, provide this information to your
telephone company.
The mounting of this device in the final assembly must be made in such a manner as to preserve the
high voltage protection between the TIP/RING Connection and the rest of the system. Typically, this
may be accomplished by maintaining a minimum spacing .100 mils between the TIP/RING Traces to
the RJ-11C Jack and low voltage portion of the system. No additional circuitry may be attached
between TIP/RING and the telephone line connection, unless specifically allowed in the rules.
The REN is useful to determine the quantity of devices you may connect to a telephone line and still
have all of these devices ring when the number is called. In most, but not all areas, the sum of the
RENs of all devices connected to one line should not exceed five (5.0). To be certain of the number of
devices you may connect to the line, as determined by the REN, you should contact the local telephone
company to determine the maximum REN for you calling area.
If your system causes harm to the telephone network, the telephone company may discontinue service
temporarily. If possible, they will notify you in advance. If advance notification is not practical, you will
be notified as soon as possible.
Your telephone company may make changes in its facilities, equipment, operations or procedures that
could affect proper functioning of your equipment. If they do, you will be notified in advance to give you
an opportunity to maintain uninterrupted telephone service.
If you experience trouble with this device, please contact XECOM at (408) 945-6640 for information on
obtaining service or repairs. The telephone company may ask you to disconnect this device from the
network until the problem has been corrected or until you are sure that the device is not malfunctioning.
The device may not be used on coin service lines provided by the telephone company (this does not
apply to private coin telephone applications which use standard telephone lines). Connection to party
lines is subject to state tariffs.
FCC Registration Number: DWEUSA-_ _ _ _ _-FA-E
Ringer Equivalence: _._B
XE2476 XECOM\11
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Terms of Sale
Devices sold by XECOM are covered by the warranty provisions appearing in its Terms of Sale
only. XECOM makes no warranty, express, statutory, implied, or by description regarding the
information set forth herein, or regarding the freedom of the described devices from patent
infringement. XECOM makes no warranty of merchantability or fitness for any purposes. XECOM
reserves the right to discontinue production and change specifications and prices at any time and
without notice. This product is intended for use in normal commercial applications. Applications
requiring extended temperature range, unusual environmental requirements, or high reliability
applications, such as military, medical life-support or life-sustaining equipment, are specifically not
recommended without additional processing and authorization by XECOM for such application.
Xecom assumes no responsibility for the use of any circuitry other than circuitry embodied in a
Xecom product. No other circuits, patents, or licenses are implied.
Life Support Policy
Xecom's products are not authorized for use as Critical Components in Life Support Devices or
Systems.
Life Support Devices or Systems are devices or systems which, (a) are intended for surgical
implant into the body, or (b) support or sustain life, and whose failure to perform, when properly
used in accordance with instructions provided in the labeling, can be reasonably expected to result
in significant injury to the user.
A Critical Component is any component of a life support device or system whose failure to
perform can be reasonably expected to cause failure of the life support device or system, or to
affect its safety or effectiveness.
Copyright, Xecom © 1994
While Xecom, Inc. has made every effort to ensure that the information presented here is accurate, Xecom will not be liable for
any damages arising from errors or omission of fact. Xecom reserves the right to modify specifications and/or prices without
notice. Product mentioned herein are used for identification purposes only and may be trademarks and/or registered
trademarks of their respective companies.
XECOM
X e com Incorporated
374 Turquoise Str eet ,Mi lpitas, CA 95035
Ph:408-945-6640 Fax:4 08-94 2 - 1 346
12/XECOM XE2476
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