XE2422H
April 2006
Low-Cost, 2400 BPS Surface-Mount Modem
Description
Features
XE2422H is a complete miniature, surface-mount,
2400 bps modem. It permits the designer to easily
incorporate dial-up communications into set top
box, security, vending, or point-of-sale applications.
212A modem protocols
XE2422H is not just a modem chip. The only
design requirements are a serial port connection to
the micro-controller and the connection to the
telephone line. The XE2422H includes transferable
FCC Part 68 Registration eliminating FCC Part 68
testing for the Xecom customer.
With the XE2422H, Xecom lowers the total cost of
modem ownership. As a complete modem, it
voice communications on an extension telephone.
dramatically reduces modem development and
certification costs. Assembly costs are reduced as
dozens of components are replaced with this single,
surface-mount module. And since Xecom tests
100% of all modules, quality is also improved. The
cost of the XE2422H is under nine dollars in
100,000 piece quantities. Contact Xecom for
pricing at other quantities
XE2422H BLOCK DIAGRAM
/Reset
TXD
ROM
RXD
Modem
/DCD
Controller
Analog
Telephone
Tip
/CTS
Front
Line
Ring
End
Interface
/INT
(DAA)
/RI
XECOM
(1)
XE2422H
XE2422H Mechanical Specifications
A
E
J
D
F
F
I
B
(bottom)
F
C
G
H
Inches
Millimeters
Dimension
Min
Typ
Max
Min
Typ
Max
A
1.595
1.600
1.605
40.51
40.64
40.77
B
0.795
0.800
0.805
20.19
20.32
20.45
C
0.147
0.152
0.157
3.73
3.86
3.99
D
0.095
0.100
0.105
2.41
2.54
2.67
E
0.055
0.060
0.065
1.40
1.52
1.65
F
0.095
0.100
0.105
2.41
2.54
2.67
G
1.045
1.050
1.055
26.54
26.67
26.80
H
0.495
0.500
0.505
12.57
12.70
12.83
I
0.995
1.000
1.005
25.27
25.40
25.53
J
0.395
0.400
0.405
10.03
10.16
10.29
XECOM
(2)
XE2422H
XE2422H Pin Configuration
Top View
Tip
1
Ring
2
13
VCC
/DCD
3
12
/INT
/DTR
4
11
/CTS
/RI
5
10
/RESET
Reserved
6
9
RXD
GND
7
8
TXD
Note: Pin 1 is marked with a white circle on the top of the module
Pin Descriptions
PIN NAME
DESCRIPTION
1
Tip
The Ring and Tip signals connect the modem to the telephone line. FCC Part 68 Rules
require a 1500 volt isolation barrier between the telephone line and all other circuits.
This isolation must be preserved throughout the system.
The telephone company places a DC “Battery” voltage across Tip and Ring on public
switched telephone lines. The XE2422H operates regardless of the polarity of this
voltage. The “Battery” voltage drives up to 120 milliampere of DC loop current.
UL60950 requires minimum creepage and clearances distances between the Tip and
Ring traces and all other circuits. Clearance is the shortest distance between conductive
circuits; creepage is the distance between conductive points along the surface
2
Ring
The Ring and Tip signals connect the modem to the telephone line. FCC Part 68 Rules
require a 1500 volt isolation barrier between the telephone line and all other circuits.
This isolation must be preserved throughout the system.
The telephone company places a DC “Battery” voltage across Tip and Ring on public
switched telephone lines. The XE2422H operates regardless of the polarity of this
voltage. The “Battery” voltage drives up to 120 milliampere of DC loop current.
UL60950 requires minimum creepage and clearances distances between the Tip and
Ring traces and all other circuits. Clearance is the shortest distance between conductive
circuits; creepage is the distance between conductive points along the surface.
XECOM
(3)
XE2422H
XE2422H Pin Descriptions (continued)
PIN NAME
DESCRIPTION
3
/DCD
/DCD is an active low output from the modem that indicates the presence of a valid
carrier signal. The SE2 register controls /DCD in the XE2422H. The default state is
for /DCD to be disabled ATSE2=04 enables /DCD.
4
/DTR
/DTR is an active low input to the modem. The operation of /DTR is controlled by
register SE2 and is normally disabled. When enabled, the modem will exit data mode
and enter command mode if /DTR is removed while the modem is on-line. In Pulse and
FSK Alarm modes raising /DTR is the only was to disconnect the data link.
5
/RI
The /RI signal reports on the presence of an incoming ring signal. When a ring occurs
across Tip and Ring, the /RI output goes low and toggles with the cadence of the ring
signal. /RI is controlled by register S0D bit 6. The default condition is for /RI to be
disabled.
6
Reserved
Reserved for future use
7
Ground
Ground provides the reference voltage for all host interface signals.
8
TXD
TXD provides the path for transmitted data and modem commands to be passed from
the host controller to the modem. A logic high on TXD represents a “Mark” condition
and a logic low represents a “Space” condition.
9
RXD
RXD provides the path for received data and modem responses to be sent from the
modem to the host controller. A logic high on RXD represents a “Mark” condition and
a logic low represents a “Space” condition.
10
/RESET
/RESET is an active low input which initiates a modem hardware reset.
11
/CTS
/CTS is an active low output from the modem. The modem asserts /CTS to indicate that
it can accept data from the terminal equipment on TXD.
12
/INT
/INT provides an active low hardware interrupt signal from the XE2422H. The operation
of this interrupt pin is programmable using registers SE2 and S08. /INT can be
programmed to indicate Loss of Carrier, Wake-on-Ring, Loss of Loop Current, or
Shared Line Activity. Once triggered the /INT line remains active until cleared by the
AT:I command.
13
VCC
VCC provides 3.3 volt power to the modem.
XECOM
(4)
XE2422H
XE2422H Electrical Specifications
Parameter
Min
Typ
Max
Units
Comments
VCC
3.0
3.3
3.6
Volts
ICC
8
mA
On Line
5
mA
Sleep
0.060
mA
Power Down
Ring Voltage Detected
26
150
VRMS
Type B Ringer
Ring Frequency Detected
15.3
68
Hz
Type B Ringer
Telephone Loop Current
16
40
120
ma
Line Impedance
600
Ohms
Data Transmit level
-9.0
dBm
DTMF Transmit Level
-2.5
0
dBm
Avg over 3 second interval
Voh
2.4
Volts
Vol
0.4
Volts
Vih
2.0
5.0
Volts
Vil
-0.3
0.8
Volts
XE2422HABSOLUTE MAXIMUM RATINGS
Storage Temperature
-25 O C to +85 O C
1 Maximum Operating Temperature Range
0 O C to +70 O C
MaximumTimeAbove Eutectic (183 O C)
90 seconds
Preheat Dwell Time
120 to 180 seconds
1 The XE2422H can be screened for operation from -40 O to +85 O C. To specify this Industrial Temperature Range add the
suffix -ITR to the model number on your Purchase Order.
XECOM
(5)
XE2422H
XE2422H Surface-Mount Soldering Instructions
The XE2422H is subject to damage if overexposed to heat during solder reflow operations. Following the
soldering instructions below will ensure that the process of soldering the module to the board does not
damage the modem.
Maximum Temperature
220 O C
Maximum Time at 220 O C
20 Seconds
Maximum Time above Eutectic (180 O C)
90 Seconds
Maximum Preheat Dwell Time
180 Seconds
Maximum Recommended Solder Temperature Profile
220 O C
180 O C
150 O C
-20 sec-
------------------------------180secmax-------------------------
max
----- 90 sec max -----
XECOM
(6)
XE2422H
XE2422H Typical Connection Diagram
To Host Serial Port
VCC
XE2422H
VCC
RJ11
/DCD
F1
/CTS
RING
RXD
TXD
TIP (22)
/RI
To System Reset
/Reset
To System Interrupt
/INT
C1
C2
GND
Parts List for XE2422HTypical Connection Diagram
Reference
Designation
Qty
Description
C1,C2
2
Cap.1000pfd,1500Vminimum
F1
1
PTC,TR600-150
Notes:
1 Capacitors, C1 and C2, may be required for EMI filtering in your system. Without these components
you may experience unintended radiation when the telephone cable is attached. C1 and C2 are high-
voltage capacitors. We recommend the Johanson Dielectrics 502S47N102KV6T. This 1000 pfd, 3000
volt capacitor will direct the high frequency harmonics to the system ground. These capacitors must
be rated at a minimum of 1500 volts to maintain the isolation required by FCC Part 68 Rules.
3. F1 is a positive thermal coefficient (PTC) device which protects the modem from excessive current
flow. These devices are required for your system to pass UL60950. Fuses may be used in place of
the PTC’s
XECOM
(7)
XE2422H
XE2422H Shared Line Features
The XE2422H monitors line conditions before, after,
Handset Interrupt:
and during calls. This allows conflicts with other
Handset Interrupt permits the modem to yield the
equipment connected to the telephone line to be
phone line when other equipment on the line goes
avoided. The XE2422H includes two Shared Line
off-hook. This prevents the modem from blocking
Features; Connect Detect and Handset Interrupt.
outgoing emergency calls when the telephone line is
shared as in residential use. The modem monitors
Connect Detect
loop current while it is off-hook. The loop current
Register SDB stores the XE2422H on-hook
will drop if another device on the line goes off-hook.
telephone line voltage. The modem checks the value
of register SDB before going off-hook to avoid
Register SF3 holds the loop current value in 1.1
interrupting a call in progress. The typical value for
milliamp increments. The XE2422H updates SF3
telephone line voltage while on-hook is 48 volts. A
regularly. The loop current value stored in SF3 is
lower voltage level indicates that the line is either
compared to the values of registers S11 and S12. If
disconnected from the modem or is currently in use.
the value S12 is greater than the value of SF3 plus
S11, then the XE2422H assumes the equipment
Register SDB is an 8 bit register. It stores the loop
connected to the telephone line has gone off-hook,
voltage as a 2’s complement number with each bit
issues the Handset Interrupt response “i” and, if so
representing 1 volt.
The Most Significant Bit
configured, issues an Interrupt to the host controller.
represents the polarity of the loop voltage.
The host controller determines whether to terminate
the call and yield the line to the other equipment.
V.22/Bell 212 Fast Connect
The XE2422H supports Fast Connect algorithms for Bell 212 and V.22 operation. These reduce the
handshaking time required for faster transaction times in applications with small data loads. Nine Registers
are used to control the Fast Connect feature as shown in the chart below
Fast
Register
Function
Units
Default
Connect
S1E
TransmitAnswer ToneLength
1 s
0x03
0x00
S1F
Answer Tone to Transmit Delay
5/3 ms
0x2D
0x00
S20
Unscrambled Ones Length (V.22)
5/3 ms
0x5D
0x00
S21
Transmit Scrambled Ones Delay (V.22)
53.3 ms
0x09
0x00
S22
Transmit Scrambled Ones Length (V.22)
5/3 ms
0xA2
0x00
S23
V.22/V.22b Data Delay Low
5/3 ms
0xCB
0x00
S24
V.22/V.22b Data Delay High
5/3 ms
0x08
0x00
S34
Answer Tone Length (S1E =0x00)
5/3 ms
0x5A
0xF0
S35
Receive V.22 Scrambled Ones Length
5/3 ms
0xA2
0x00
XECOM
(8)
XE2422H
XE2422H AT Commands
The XE2422H uses a simplified "AT" command set
Alarm Mode:
for configuration and control. This section describes
The XE2422H supports a unique set of commands
theAT command format and lists the AT commands,
to establish alarm industry connections. Both Pulse
registers and result codes. XE2422H "AT"
messaging and FSK formats are supported. The
commands have three operational modes; command
AT!1 command initiates Pulse messaging and AT!2
mode, alarm mode and data mode. The Data Rate
initiates FSK messaging. The ATD command must
for the XE2422H is set by Register SE0.
precede either AT! command to begin the Alarm
transaction. In Alarm mode, /DTR must be
Data Mode: The XE2422H enters data mode
removed to disconnect the modem link. /DTR is
after it connects to a remote modem and issues the
activated by setting register SE2 bits 4 and 5.
appropriate result code.
In the data mode the
modem sends all data presented on Transmit Data
Pulse Mode: In Pulse Mode messages are passed
(TXD) to the remote modem and puts data from the
using DTMF tones. The receiving station
remote modem onto Received Data (RXD). When
acknowledges
receipt
of
the
message
by
the modem exits data mode, it issues a "NO
transmitting the “Kissoff” tone. A sample
CARRIER" result code.
transaction is shown below.
Command Mode:
The XE2422H enters
Alarm Panel
XE2422H
command mode on power-up, reset, a lost
ATDT#!1<message 1><CR>
connection, or receipt of the escape code. In
K
command mode the modem accepts commands
from the host on transmit data. Appropriate result
!<message 2><CR>
codes are returned on RXD.
K
!<message n><CR>
Command Line Format
Command lines issued to the modem follow a strict
K
format. Each command line begins with the prefix
Disconnect is accomplished by raising /DTR.
AT. All commands except the “z” command must
be entered in upper case characters. The command
FSK Mode: In FSK Mode messages are passed
line is a string of commands between the AT prefix
on a 300 bps, half-duplex carrier signal. The X1,
and the carriage return which terminates the
X2, and X3 commands switch the modem between
command.
The command buffer stores the
monitoring the line for acknowledgments (X1),
command line and executes it upon receipt of a
transmitting
messages
(X2),
and
receiving
carriage return. Commands will be executed in the
messages (X3). As in the pulse mode disconnect is
sequence they appear in the command line.
only possible by pulling the /DTR signal high.
Result Codes - The modem issues a result code
after each command line. Result codes may be sent
as single characters or single characters followed by
a carriage return.
XECOM
(9)
XE2422H
XE2422H AT Commands
An asterisk indicates the factory default
Z - Reset -
A - Answer Command -
z - Wake from Sleep Mode on Ring
D - Dial Command -
!1<message> - Switch to Pulse Mode: This
0-9,A-D, #, * = Dialing Digits
command must follow the dialing command in the
P = Pulse dial
same command string.
T = Tone dial
!2<message> - Switch to FSK Mode: This
,
= Pause for two seconds
command must follow the dialing command in the
I = Pause for 125 milliseconds
same command string. This command allows the
; = Return to the command state
modem to establish a 300 bps half-duplex FSK