XECOM XE0056
DAA Module for 33,600 bps and 56K Analog Modems
XE0056
09-97
Description
Xecom created the XE0056 modular DAA
specifically for high-speed analog modems. The
XE0056 is a complete DAA optimized to pass
33.6K and 56K bps analog modem signals. The
XE0056 guarantees the highest speed modem
connection supported by the telephone line
conditions.
Establishing and maintaining a high-speed data
link requires a linear signal response across the full
voice band. The DAA must maintain this linearity
over a variety of local loop conditions. Xecom
engineers used proprietary design tools for realtime analysis of the DAA design. The result is a
complete telephone line interface with a typical
total harmonic distortion of -85 dB.
Like all Xecom DAA modules, the XE0056 is a
complete DAA. It includes the line transformer,
line current holding circuit, ring detector, and
hookswitch. The XE0056 also complies with FCC
Part 68 Rules for direct connection to the
telephone network.
Features
* Compatible with analog data transfer to 56K bps;
* Typical Total Harmonic Distortion -85 dB ;
* Small Size:
0.95 inch by 0.925 inch by 0.370 inches;
* FCC Part 68 Compliant;
* Integral Low-Distortion Telephone Line Transformer;
* Ring Detection;
* Operates on a Single +5 Volt or + 3 Volt
Power Supply;
* Solid-State Hookswitch Control
* Extended Temperature Ranges available
xecom
XE0056 Block Diagram
Line
Transformer
Line Current
Holding
Circuit
Hookswitch
Ring
Detector
T1
T2
OH
RI
Tip
Ring
Pin Configuration
1
2
3
4
9
8
7
6
5
Gnd
T1
VCC
T2
Tip
Ring
OH
RI
XE0056
XECOM (2) XE0056
XE0056 Mechanical Specifications
A 0.905 0.945 22.99 24.00
B 0.930 0.970 23.62 24.64
C 0.360 0.380 9.14 9.65
D 0.790 0.810 20.07 20.57
E 0.390 0.410 9.91 10.41
F 0.120 0.140 3.05 3.56
G 0.065 0.085 1.65 2.16
H 0.065 0.085 1.65 2.16
J 0.090 0.110 2.29 2.79
K 0.430 0.450 10.92 11.43
Inches Millimeters
Dim Min Max Min Max
Pins are .010 by .020 inches. All Pins are tin-plated
for solderability.
XE0056 Typical Connection Diagram
RING
TIP
RJ11
+5 Volts
Off hook
Ring Detect
1
2
3
4
9
8
7
6
5
Gnd
VCC
OH
RI
TXA1
T1
T2
RXA
TXA2
Rm
Z1
Z2
C1
MOV1
C2
C3
FB1
FB2
Modem Analog
Front End
XE0056
R1
R2
Recommended Parts
Designation Description
R1, R2 15 ohms, 1/2 watt
Rm Line Impedance Matching Resistor, 280 ohms
C1 .01 microfarad
C2, C3 47 picofarad, 3000 Volts (Sprague Part Number 30GA-T47)
Z1, Z2 Zener Diode 4.3 Volts
FB1, FB2 Ferrite Beads (TDK Part Number CB30-453215B)
MOV1 Minimum Breakover 220 volts (Teccor Part Number P2600BA70)
Denotes Pin 1
A
B
C
F
E
J
H
D
G
XECOM (3) XE0056
Pin Descriptions
PIN NAME DESCRIPTION
1 Ring Ring is one wire of the two-wire telephone line connection (RJ11 Pin 4). 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. Xecom recommends 0.100 inch spacing
between traces connected to Ring and all other conductors to preserve this isolation.
2 Tip Tip is the second wire of the two-wire telephone line connection (RJ11 Pin 3). 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. Xecom recommends 0.100 inch
spacing between traces connected to Tip and all other conductors to preserve this isolation.
3 OH OH provides hookswitch control to the modem. OH is an active high input. Activating OH
closes the hook-switch causing the XE0056 to seize the local telephone line. The telephone
line connection is dropped when OH is dropped.
The OH line can be pulsed to simulate rotary dialing. The pulse rate during rotary dialing is
ten pulses per second. Each digit is dialed as a series of pulses created by closure of the
hook-switch. (from one pulse for the digit one to ten pulses for the digit zero) The pulses on
OH must be asymmetrical so that the hook-switch is closed for thirty-one milliseconds and
open for sixty-nine milliseconds. An inter-digit delay of at least one hundred milliseconds is
required.
4 /RI /RI, Ring Indicate, is an active low output from the modem. /RI active indicates the presence
of an incoming call. The singal on /RI provides a square wave representation of the Ring
signal. This permits intelligent monitoring of the ring signal. The XE0056 recognizes ring
voltages of thirty-eight to one hundred fifty volts RMS in the frequency range of sixteen to
sixty-eight Hertz.
5 T1 T1 in conjunction with T2 provides the differential input/output for the analog signal. T1
connects directly to the secondary side of the line transformer embedded into the XE0056.
To match the impedance of the DAA to the 600 ohm telephone line, a 280 ohm resistor is
required on T1 or T2.
6 Not Used
7 VCC VCC provides +5 Volt power source for the XE0056. VCC powers the /RI and OH control
lines.
8 T2
T2 in conjunction with T1 provides the differential input/output for the analog signal. T2
connects directly to the secondary side of the line transformer embedded into the XE0056.
To match the impedance of the DAA to the 600 ohm telephone line, a 280 ohm resistor is
required on T1 or T2.
9 GND
Ground connection to the XE0056. This signal provides the reference for the /OH output and
/RI input. This pin should be connected to the systems digital ground.
XECOM (4) XE0056
XE0056 ABSOLUTE MAXIMUM RATINGS
Storage Temperature -25OC to +85OC
Operating Temperature Range 0OC to +70OC
Maximum Lead Temperature 260OC
(soldering 2 seconds per wave)
Electrical Specification (Vcc=+5v ±10%, Ta=0 to 70 deg C)
Power Supply Current Off-hook 10 mA
On-hook 0.5 mA
Transmit Insertion loss 600 Ohm Impedance, 1800 Hz 4.5 6.0 7.0 dB
Receive Insertion loss 600 Ohm Impedance, 1800 Hz 4.5 6.0 7.0 dB
Line Matching Impedance Input to T1 and T2 270 280 290 ohms
Line Impedance At 1800 Hz 540 600 660 ohms
Total Harmonic Distortion 600 Ohm Impedance, 1800 Hz -80 -85 dB
signal level -10 dBm
Ring Detect Sensitivity Min. AC voltage between Tip & 38 150 Vrms
Ring Type B ringer
/RI Output Voltage Ring signal present 0.2 0.5 Volts
No Ring signal across Tip/Ring 2.0 5.0 Volts
Hook-Switch Control ON: (off-hook) 2.0 3.0 Volts
OFF: (on-hook) 0.2 0.5 Volts
Loop Current Off-Hook current draw from 20 100 mA
Telephone Line
Parameter Conditions Min Typ Max Units
XECOM (5) XE0056
Dialing:
The public switched telephone network permits
tone and rotary dialing. The XE0056 is compatible
with both types. Tone dialing requires an external
signal source to provide the dialing tones to the
XE0056. Rotary dialing is accomplished by
pulsing the OH line on the XE0056.
Tone Dialing: To tone dialing the XE0056 seizes
the line, OH active. The DTMF, Dual Tone
Multiple Frequency, dialing tones are placed
across T1 and T2. Each digit uses a unique tone
pair. The higher frequency tone is always larger
than the lower frequency one. Transmit the tones
for a minimum of 70 milliseconds, and leave a
minimum of 70 milliseconds between digits.
The chart below shows the correct frequencies for
each digit.
Digit Lower Tone Upper Tone
1 697 1209
2 697 1336
3 697 1477
4 770 1209
5 770 1336
6 770 1477
7 852 1209
8 852 1336
9 852 1477
0 941 1336
* 941 1209
# 941 1477
Pulse Dialing: The XE0056 generates dialing
pulses through momentary switch-hook closures.
Each digit is dialed as a series of pulses, from one
pulse for a one to ten pulses for a zero. The pulse
rate during rotary dialing is ten pulses per second.
The dialing pulses are asymmetrical. To achieve
the correct duty cycle the hook-switch is closed for
thirty-one milliseconds then opened for sixty-nine
milliseconds. An inter-digit delay of at least one
hundred milliseconds separates the digits.
Signal Levels:
FCC Part 68 Rules set the allowable level of all
signals placed on the telephone line other than live
voice. For the most common certification type, a
"Permissive" connection, data, fax, synthesized
voice and other information signals are limited to 9 dBm. Zero dBm is 1 milliwatt through a 600
ohm load. The rules provide for a different limit
for DTMF, Dual Tone Multiple Frequency, tones.
The combined power of the two tones may be as
high as 0 dBm with the higher frequency tone at
least 2 dBm larger than the lower tone.
Insertion Loss: There is some loss of signal
power as the information signal passes through
the XE0056. This "insertion" loss should be taken
into account when placing signals across T1 and
T2 for transmission. The typical insertion loss of
the XE0056 is 6 dBm.
Total Harmonic Distortion:
Total harmonic distortion is the most common
measure of the quality of the signal path provided
by the DAA. The primary sources of this distortion
are the telephone line transformer and the line
current holding circuit, although board layout and
other factors can introduce distortion.
Total harmonic distortion varies with frequency.
The voice band provided by the telephone line is
limited to under 4000 Hz. High speed modems
such as 33.6 KBPS and 56KBPS require virtually
all of this bandwidth for signal transmission. Even
if the total harmonic distortion of a device is very
good in the center portion of the spectrum, it can
be compromised if distortion greatly increases at
the outer limits of the voice band below 1000 Hz
and above 3000 Hz. Figure 5 below shows the
typical total harmonic distortion of the XE0056
across the entire voice band.
XE0056 Applications Notes
XECOM (6) XE0056
XE0056 Applications Notes (continued)
Figure 5: Total Harmonic Distortion:
Note: This chart represents the total harmonic
distortion of the complete DAA not just the
telephone line transformer. Distortion
measurements of the transformer only will
show much lower distortion.
2/4 Wire Conversion:
Full Duplex communications over a two-wire
telephone line requires that transmit and receive
signal share the available bandwidth. The two-tofour wire convertor separates these signals at the
host interface. Most modem analog front end
chips incorporate an internal 2/4 wire convertor
making it unnecessary to provide one in the DAA.
If you are using the XE0056 for an application
other than a modem, such as voice processing, or
your modem analog front end does not provide the
2/4 wire convertor, you will need to provide a
discrete 2/4 wire convertor. Figure 6 shows a
simple 2/4 wire convertor circuit.
Figure 6: 2/4 Wire convertor
The performance of the 2/4wire convertor is
measured by its Transhybrid Loss. The
Transhybrid Loss shows how much he 2/4 wire
convertor attenuates the transmit signal on the
received data line. The circuit above provides a
typical Transhybrid Loss of 20 dB.
The Transybrid Loss will vary with the quality of the
impedance match to the telephone line. Even
when the recommended value for the impedance
matching resistor, R6, is used variations from line
to line alter the impedance match. The value of
R3 can be changed to improve the Transhybrid
Loss.
The 2/4 wire convertor also amplifies the transmit
and receive signals to compensate for the insertion
loss of the DAA. This circuit provides 6 dB gain of
both the transmit and receive signals. The values
of R1 and R2 set the transmit gain. The values of
R4 and R5 set the receive gain.
-50
-55
-60
-65
-70
-75
-80
-85
Total
Harmonic
Distortion
500 1000 1500 2000 2500 3000 3500 4000
Transmit
Receive
T1
T2
4558
4558
R1
R2
R3
R4
R5
R6
20K
20K
10K
280 ohms
40K
11.5K
XE0056
XECOM (7) XE0056
Telephone Line Connection Information
When developing a product to be connected to the telephone line, it is necessary to use a circuit known
as a Data Access Arrangement (DAA) approved by the appropriate governmental agency. In the US this
agency is the Federal Communications Commission (FCC), while in Canada it is Industry Canada (IC).
These agencies test and approve the product to ensure that it meets their specifications, thereby
protecting the telephone system from damage and protecting the user from high voltage transients (such
as lightning strikes) which may come down the telephone line.
The XE0056 has been designed to meet all FCC Part 68 requirements for hazardous voltage, line
impedance and leakage current. If the system transmits data, synthesized voice, or DTMF tones on the
telephone line, the user must certify that the signals transmitted meet basic FCC requirements for
maximum transmission levels, out of band energy and billing delay. Full details may be obtained from
the FCC under Part 68 of the FCC Rules and Regulations, or in Title 47 of the Code of Federal
Regulations, however the basic requirements are as follows:
1. Maximum Transmit Level
For the normal “permissive” (standard) telephone line, equipment which transmits data (such as a
modem) must not exceed a transmission level of -9 dBm.
2. Out of Band Energy
Data equipment must not transmit “out of band” energy on the telephone line which exceeds the following
limits:
Frequency Range Max. Power
3995 Hz to 4005 Hz -27 dBm
4005 Hz to 12 kHz -20 dBm
12 kHz to 90 kHz -55 dBm
90 kHz to 270 kHz -55 dBm
270 kHz to 6 MHz -15 dBm
3. DTMF Transmission Level
If the system is capable of DTMF dialing, the maximum DTMF transmission level must be less than 0
dBm averaged over a 3 second interval.
4. Billing Delay
A delay of 2 seconds or greater is required after the time the XE0056 is taken “off hook” and before any
information is transmitted. This is required to ensure that billing information may be exchanged between
telephone company central offices without interference.
The user of the XE0056 must certify to the FCC that the final system meets the requirements of Part 68
which include the criteria above as well as the high voltage protection provided by the XE0056. This is
generally accomplished through an independent testing lab which tests the System and submits the
proper paperwork to the FCC for approval. Since the XE0056 already complies with FCC Part 68 rules,
this is a relatively simple process.
XECOM XE0056
Copyright, Xecom © 1997
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.
X
ecom Incorporated
374 Turquoise Street,Milpitas, CA 95035
Ph:408-945-6640 Fax:408-942-1346
xecom
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 lifesustaining 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.
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