CH1817
Family of Low Profile DAA Modules
INTRODUCTION
FEATURES
The CH1817 is a Family of Low Profile Data Access
Arrangement (DAA) Modules.
They are compatible
with all modem chip sets. These devices have been
tested to meet or exceed FCC Part 68 requirements
and are Canadian DOC approvable. They are also
recognized by Underwriters Laboratories to UL 1459
Specifications.
The CH1817 modules are ultra small (1.0” x 1.0”
x0.35”) affording an easy integration into space-
sensitive designs, including laptop and hand-held
computer based products.
The CH1817 family of
products may be socketed or mounted directly onto a
Printed Circuit Board (PCB).
The telephone line
connection is made through TIP and RING to an RJ-11
mode noise rejection filter
jack or equivalent.
Reduced transmit
attenuation
The CH1817 is intended for use with FAX/modem chip
sets that have a data throughput of up through
transmission insertion loss.
V.32bis.
For High Speed Applications, Cermetek
recommends the CH1837A.
FUNCTIONAL DESCRIPTION
Ring Detection. Referring to the block diagram in
V CC
GND
Figure 1, incoming ring detection is performed by the
CH1817 and the RI pin is set Low during the 2 second
(typical) ring period and is restored to High for the 4
seconds (typical) between rings. During incoming ring
SURGE
TIP
signal activity, the RI output is pulsed at the same
AND
ISOLATION
frequency as the ringing signal, typically 20Hz. Figure
PROTECTION
RING
2 contains additional external circuitry which may be
CIRCUITRY
used to provide an envelope indication of the ring
signal. The internal ring detection circuit is designed
to deter false indications due to pulse dialing or noise
on the line.
The RI output of the CH1817 is diode protected.
XMIT
HYBRID
OFF-HOOK
Therefore, an external pull-up resistor (R>100Kohm)
2W/4W
SWITCH
to +5V may be utilized to activate the ring detection
CONVERTER
RCV
circuit when the CH1817 is not connected to power.
RING DET.
This can be handy in designs where power
RI
consumption is of concern.
When circuited in this
manner, there is virtually no current draw until a ring
signal is present.
OFFHK
RI
Output: Active low
Opto coupler, 30K Ω pull-up
Square wave: 15-68Hz (Typ. 20Hz)
Sensitivity: 38Vrms across Tip & Ring
Figure 1. CH1817 DAA Functional Block Diagram.
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CH1817 Family of Low Profile DAA Modules
Hook Switch. The OFFHK input is used to control the
TRANSMIT SIGNAL
on-hook and off-hook status of the CH1817. When
The outgoing analog signal to be transmitted through
OFFHK is low, the CH1817 is in the On-Hook State.
the phone line should be applied to the XMIT pin (with
This indicates to the CO that the CH1817 is ready to
respect to GND) and must be AC coupled as shown in
receive calls.
When OFFHK is high, the CH1817
Figure 2. For the CH1817-D a XMIT (+) and XMIT (-)
allows the CO supplied loop current to flow, indicating
pins provide a differential input.
The CH1817-L
either it is answering a call or preparing to place a call.
attenuates the transmit signal by 9.5dB, 0dB for the –D
option. Therefore, a transmit signal of 0dBm for the –L
OFFHK
option (-9.5 dB for –D) applied to XMIT will comply
Input: Active High
with the FCC Part 68 requirement for data signals of –
Active Current: 4mA
9dBm across TIP and RING.
2-Wire To 4-Wire Hybrid Converter. This block has
two functions:
RECEIVE SIGNAL
1. It applies the XMIT signal to the phone line.
The incoming analog signal appearing between TIP
2. It subtracts the desired signal from the total
and RING is presented at RCV with respect to GND
outgoing signal on the phone line to derive the
and must be AC coupled to the user equipment
RCV signal.
receive input. The CH1817 does not gain the receive
signal.
Receive signals can vary from a maximum
The accuracy of this derivation depends on how
strength of –9dBm to below –50dBm.
closely the impedance of the phone line matches 600
Ohms. Generally, a small amount of the XMIT signal
will appear at RCV. The ratio of the applied XMIT
RCV
signal to the received XMIT signal is called Trans-
Gain: 0dB
Hybrid Rejection, or Trans-Hybrid Loss. On a 600 Ω
Out impedance: 100 Ω
phone line, the CH1817 DAAs have very high trans-
Typical Output Signal:
hybrid rejection, typically 23 dB.
-9dBm to –50dBm
2.5Vrms to 0.27mVrms
NOTE
Signal referenced to GND
The FCC requires that the DTMF tone not exceed
AC coupling required
0dBm.
XMIT
CH1817-D
CH1817-L
CH1817-DM
CH1817-LM
Attenuation
0dBm
9.5dBm
6.5dBm
6.5dBm
Input Impedance
150K Ω
150K Ω
150K Ω
150K Ω
Figure 2. Typical CH1817 Application.
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CH1817 Family of Low Profile DAA Modules
Table 1.
CH1817 Family Pin Description.
Pin
Name
I/O
Function
1
TIP
I/O
TIP . Direct telephone line connection.
2
RING
I/O
RING . Direct telephone line connection.
3
OFFHK
I
OFF HOOK . When set LOW, the CH1817 is placed On-Hook. When set HIGH, the
CH1817 is placed Off-Hook to answer or place a call. This input can also be used
for pulse dialing. NOTE: When answering incoming calls in response to a ring
indication on RI, internal relay contact degradation may occur if OFFHK is set HIGH
before RI returns to its HIGH state.
4
RI
O
RING INDICATION . It is asserted LOW by the CH1817 during the 2 second ON
portion of the incoming AC Ring Signal and is asserted HIGH during the 4 second
idle period between rings. An envelope of the AC ring signal may be created using
the application circuit shown in Figure 2.
5
RCV
O
RECEIVE . This provides the signal or audio output with respect to ground and must
be AC coupled with a 0.1 µ F capacitor to eliminate DC offset.
6
XMIT(-)
I
TRANSMIT SIGNAL (-) . Input a differential AC coupled audio signal with respect to
or
or
XMIT(+), CH1817-D versions only. All others, No Connection. For single ended
N/C
-
operation of CH1817-D, connect this pin to ground through a 0.1 µ F capacitor.
7
VCC
I
POWER SUPPLY . +5V ± 5%
8
XMIT(+)
I
TRANSMIT SIGNAL (+) . Input an AC coupled audio signal with respect to ground.
Input a differential signal with respect to XMIT(-) for the CH1817-D versions only.
9
GND
I
Ground . Must be connected to signal ground. Note: Noise should be less than
25mV peak-to-peak.
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CH1817 Family of Low Profile DAA Modules
CH1817-L: LOW POWER
5. The DAA Module is a sensitive subsystem that
The L Family is a Low Power version of the CH1817
should be treated as
any other integrated
DAA.
When Off-Hook, this DAA draws only 4mA
component.
Pay special attention to the power
through V cc . When On-Hook, the L Family can be
supply to the DAA. The device handles signals in
configured so that the Ring Detection circuit can be
the millivolt range. Even though it is designed to
handle noise in the power supply, steps should be
activated by a pull-up resistor on RI while V cc
has
taken to assure the noise level does not exceed
been disconnected from the power supply, thus
50mV peak-peak.
making the On-Hook power consumption virtually zero
(See Figure 4).
6. For data calls, Part 68 rules require silence on the
phone line for at least 2 seconds after a data call
has been completed to allow central offices to
CH1817-D: 0 dB XMIT ATTENUATION
exchange billing information and specifies the
The D option has 0.0 dB insertion loss (typical) with
transmit level must not exceed -9dBm. The FCC
respect to a differential input between XMIT (-) and
rules also require that for voice calls the final
XMIT (+). This allows the maximum signal strength of
system meet the requirements of Part 68 for Out-of
–9dBm to be input while maintaining FCC compliance.
Band
Energy,
and
DTMF
Transmit
Levels.
To use the CH1817-D as single end input device,
Because
the
CH1817
already
meets
FCC
ground the XMIT (-) pin through a 0.1uF capacitor.
requirements for Part 68 registration for High
Voltage
isolation
and
Surge
Protection,
the
certification of the product is normally a simple
MOUNTING THE DAA
process that often can be completed directly with
The DAA can be soldered directly to the host circuit
the FCC. If desired, independent testing labs are
card or installed in sockets. To avoid the problems of
available that can test the system and submit the
contamination, hand soldering is preferred to wave
required paperwork to the FCC for approval.
soldering. When hand cleaning use only deionized
Cermetek can assist with the registration.
water; when wave soldering use washless flux.
7. The CH1817 DAA as is meets or exceeds the
hazardous
voltage,
surge
and
leakage
DESIGN CONSIDERATIONS
requirements of the FCC.
For applications that
The CH1817 DAA includes circuits that couple the
connect to Canadian phone lines, governed by the
modem signals to the phone line and provides FCC
DOC (Department of Communications) and to
required
isolation
and
protection.
The
FCC
further protect the CH1817 from field failure on
registration process by the host product can be
excessively poor quality lines and to maintain UL
minimized provided that the following guidelines are
recognition, a higher level of transient protection is
followed.
required, thereby making mandatory the circuit
consisting of two fuses and one varistor as shown
1. The mounting of the DAA in the final assembly
in Figure 3. Adding these three devices will not
must be made so that it is isolated from exposure to
affect FCC registration. Components L1, L2, C1,
any hazardous voltages within the assembly.
C2 are optional and serve two purposes. First, they
Adequate separation and restraint of cables and
restrict high frequency signals from reaching the
cords must be provided.
phone line and thereby add EMI protection.
Second, they protect against externally generated
2. Connection to the phone line should be made
RFI from degrading the modem’s ability to operate
through a standard FCC approved RJ-11C jack or
on proper carrier signals. Adding these devices will
equivalent.
not affect FCC, DOC, or UL registration.
3. Circuit board traces from the DAA’s TIP and RING
pins must exceed 0.1 inch spacing from all other
traces or other conducting material. The purpose
for this pacing is to maintain 1000 VAC isolation
between the phone line and the other traces.
Traces should have a nominal width of 0.020
inches or greater.
4. TIP and RING traces should be as short as
possible and should be oriented to prevent direct or
induced coupling with other signals on the host
circuit card.
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CH1817 Family of Low Profile DAA Modules
Figure 3.
Telephone Line Interface.
1. RJ-11 Jacks must be provided by one of the
vendors on the list.
Refer to Application Note
#130, Summary of Recommended Suppliers.
2. Current Line Device: F1 and F2 – 1.25amp.
A. UL 1459 must use a current limit device. A
Poly Fuse is recommended as this device
resets automatically after each power surge.
B. Resistors (10ohm carbon film or SMD 1/8W
minimum)
may
be
used
for
non
UL
applications.
3. Over Voltage and Lightning Protection.
A. DOC (Canada) may require external current
limiting devices. Use 1ohm resistors (carbon
film or SMD parts 1/8W minimum) in each lead
(TIP and RING). You may substitute fuses or
the Poly Fuse described in Section 2.
Figure 4. Low Power Ring Detection.
B. For lightning prone areas where there are
more than 2 storms per year, provide an earth
ground connection and use a three terminal
sidactor or similar device that provides metallic
and longitudinal protection.
This must also
include the current protection in Section 2.
4. EMI/RFI Suppression.
The capacitor/ inductor network should be located
as close to the RJ-11 Jack as possible with an
excellent ground path to the chassis. Capacitors
C1 and C2 should not exceed 0.005 µ F.
They
must have a rating of 1.5KV and typically have a
value of 0.001 µ F ± 20%. Inductors L1 and L2 are
ferrite cylinders and provide attenuation to high
frequencies
from
system
level
components
external to the CH1817. The required values must
be empirically determined for each product design
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CH1817 Family of Low Profile DAA Modules
Table 2.
CH1817 DAA Electrical Specifications.
V CC =+5VDC ± 5%, T A =0° to 55°C
Parameter
Conditions
Min.
Typ.
Max.
Units
Supply Current
Off-Hook
4
6
mA
Off-Hook
0.6
1.5
mA
Transmission
Attenuation between transmit input and telephone line at
Insertion Loss
1800Hz with 600Ohm termination:
CH1817-L measured XMIT(+) with respect to GND
9.0
9.5
10.0
dBm
CH1817-DM measured XMIT(-) with respect to XMIT(+)
6.0
6.5
7.0
dBm
CH1817-LM measured XMIT(+) with respect to GND
6.0
6.5
7.0
dBm
CH1817-D measured XMIT(-) with respect to XMIT(+)
-0.5
0.0
0.5
dBm
Receive Gain
Gain between telephone line and receive output at
-0.5
0.0
0.5
dBm
1800Hz with 600Ohm termination
Telephone Line
At 1800Hz
550
600
650
Ohm
Input Impedance
Trans-Hybrid Loss
Attenuation between the transmitter input and receiver
18
23
dBm
output at 1800Hz with 600Ohm termination
Transmit Input
At 1800Hz
120
150
200
kOhm
Impedance
Receive Output
At 1800Hz
100
1000
Ohm
Impedance
Ring Detect
AC voltage between Tip and Ring
38
V rms
Sensitivity
Ringer Equivalency
Type “A”
0.2
A
Number (REN)
Hook Switch Control
4
mA
Current
Loop current
20
80
mA
Weight
10
gm
Figure 6. Pin Connections.
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CH1817 Family of Low Profile DAA Modules
Figure 7. Mechanical Specifications.
Table 2A. Non-RoHS Complaint Product Family Summary.
Model
Summary of Features
Operating Temperature
CH1817D
UL1459 Listed, XMIT attenuated by 0.0dBm, Differential input
0 ° C to 55 ° C
CH1817L
UL1459 Listed, XMIT attenuated by 9.5dBm, Single ended input
0 ° C to 55 ° C
CH1817LM
UL1459 Listed, XMIT attenuated by 6.5dBm, Single ended input
0 ° C to 55 ° C
CH1817DM
UL1459 Listed, XMIT attenuated by 6.5dBm, Differential input
0 ° C to 55 ° C
CH1817ET*
UL1459 Listed, XMIT attenuated by 9.5dBm, Single ended input
-40 ° C to 85 ° C
CH1817LET*
UL1459 Listed, XMIT attenuated by 9.5dBm, Single ended input
-40 ° C to 85 ° C
Table 2B. RoHS Complaint Product Family Summary.
Model
Summary of Features
Operating Temperature
CH1817RD
UL1459 Listed, XMIT attenuated by 0.0dBm, Differential input
0 ° C to 55 ° C
CH1817RL
UL1459 Listed, XMIT attenuated by 9.5dBm, Single ended input
0 ° C to 55 ° C
CH1817RLM
UL1459 Listed, XMIT attenuated by 6.5dBm, Single ended input
0 ° C to 55 ° C
CH1817RDM
UL1459 Listed, XMIT attenuated by 6.5dBm, Differential input
0 ° C to 55 ° C
CH1817RET*
UL1459 Listed, XMIT attenuated by 9.5dBm, Single ended input
-40 ° C to 85 ° C
CH1817RLET
UL1459 Listed, XMIT attenuated by 9.5dBm, Single ended input
-40 ° C to 85 ° C
*
*Available upon special order only. Contact factory for details.
2006 Cermetek Microelectronics, Inc.
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CH1817 Family of Low Profile DAA Modules
Cermetek reserves the right to make changes in specifications at any time and without notice. The information furnished by
Cermetek in this publication is believed to be accurate and reliable. However, Cermetek assumes no responsibility for its use, or for
any infringements of patents or other rights of third parties resulting from its use. No license is granted under any patents or patent
rights of Cermetek.
Cermetek provides the user with a FCC (USA) and IC (Canada) Approved or device. However, Cermetek does not have influence
over nor knowledge of the specific user application environment. Therefore, for FCC and IC Approved or Approvable devices, the
user assumes all risk for maintaining compliance to registration.
Printed in U.S.A
1390 BORREGAS AVNUE | SUNNYVALE CA 94089 | LOCAL: 408-752-5000 | TOLL FREE: 1-800-882-6271 | FAX: 408-752-5004
CERMETEK WEB SITE: http://www.cermetek.com | EMAIL: sales@cermetek.com
2006 Cermetek Microelectronics, Inc.
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