CH1840
Low Profile Data Access Arrangement (DAA) Modules
INTRODUCTION
FEATURES
The CH1840 is an ultra small, low profile Data Access
  • Works with all modem chip sets.
  • Arrangement (DAA).
    Its modular construction and
  • Available in 0 dB, -6 dB, and –9 dB insertion
  • single +5 Volt D.C. power requirement simplify your
    losses.
    development process. Specifically designed for both
    voice and data, this allows direct connection of these
  • Available in extended temperature operation, -40C
  • circuits to the telephone lines. The CH1840 has FCC
    to +85C.
    Part 68 registration that can be transferred to your
  • Complete DAA function.
  • product. Simply attach the included registration sticker
  • Voice and data.
  • to the outside of your product. This eliminates the
  • FCC Part 68 registered.
  • costs and delays associated with Part 68 testing and
  • Registration conveyed to user.
  • registration.
  • Hook switch control.
  • Ring detection.
  • The CH1840 has also been designed to meet the
    requirements
    of
    Canada’s
    Department
    of
  • Single +5V operation.
  • Communication (DOC). However, it is necessary to
  • Pulse dial capability.
  • register your product with the DOC before use in
    Canada.
    FUNCTIONAL DESCRIPTION
    The CH1840 requires only 1.5 square inches of circuit
    The operation of the CH1840 can be broken down into
    board space and presents a profile of only 0.35 inches
    the functional blocks shown in Figure 1.
    in height. This DAA can either be mounted directly on
    a printed circuit board or socketed.
    Connection is
    1) Phone line control
    made through 0.025-inch square pins on 0.10-inch
    2) Billing delay
    centers.
    The telephone line connection is made
    3) Ring detection
    through a user supplied RJ-11 jack.
    4) Signal Path
    5) 2- to 4-wire converter
    The CH1840 DAA is designed for use with a variety of
    Control inputs and status outputs for the CH1840 are
    voice circuitry and LSI modem/fax chip sets.
    This
    compatible with 5 Volt CMOS.
    See the Electrical
    device is ideal for fax and modem applications up
    Specifications.
    through V.32bis. The CH1840 is pin compatible with
    the CH1817.
    Figure 1.
    CH1840 DAA Functional Block Diagram.
    2004 Cermetek Microelectronics, Inc.
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    Document No. 607-0011 Revision B1 (09/04)
    Cermetek Microelectronics, Inc.
    CH1840 Family of Low Profile DAA Modules
    Phone Line Control.
    In the Public Switched
    RING DETECTION
    Telephone Network (PSTN), the wires from a
    The central office signals an incoming call by placing a
    telephone to the phone company’s central office (CO)
    ring signal on the local loop. The CH1840 monitors
    are referred to as the local loop.
    the loop for this signal. The Ring Indication output, RI,
    is normally HIGH. When ringing appears, RI is set
    2-Wire To 4-Wire Hybrid Converter. This block has
    LOW during the typically 2 second ring period and is
    two functions:
    restored to HIGH for the typically 4 seconds between
    rings. The ring detection circuit is designed to prevent
    Drawing current from the local loop signals the central
    false indications due to noise or pulse dialing on the
    office that the telephone is Off Hook, that is, either
    line.
    answering a call or preparing to place a call. In the
    CH1840, this function is controlled by the OFFHK
    The RI output of the CH1840 is diode protected so that
    signal. When this input is LOW, the CH1840 is On-
    an external pull-up resister(R> 100Kohm) to +5V may
    Hook, indicating to the central office that it is not using
    be utilized to activate the ring detection circuit when
    the line.
    CH1840 can pulse dial by togging the
    the DAA is not connected to power.
    This can be
    OFFHK input
    handy with designs in which power consumption is of
    concern.
    When circuited in this manner, there is
    For data calls, FCC Part 68 rules require silence on
    virtually no current draw until a ring signal is present.
    the phone line for at least 2 seconds after the call has
    See Figure 3.
    been completed to allow central office to exchange
    billing information. The CH1840 assures conformance
    TRANSMIT SIGNAL
    to this requirement by stating a two-second timer on
    The outgoing analog signal to be transmitted through
    the LOW to HIGHT transition to OFFHK and
    the phone line should be applied to the XMIT pin (with
    squelching transmitted signals until the time expires.
    respect to GND
    The CH1840 defeats this function when Voice Mode is
    selected on the Data/Voice pin.
    The CH1840 attenuates the transmit signal by 9.5, dB
    (0dB for the D option applied to XMIT will comply with
    the FCC Part 68 requirement for data signals of -9dBm
    across Tip and Ring. In all cases in the data mode,
    the CH1840 prevents the signal level from being
    greater than -9dBm at Tip and Ring.
    Figure 2.
    Typical CH1840 Application.
    2004 Cermetek Microelectronics, Inc.
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    CH1840 Family of Low Profile DAA Modules
    excessive Power is detected and returns LOW when
    the transmitted signal is unsquelched.
    Since FCC Part 68 rules have no limitation to the
    signal strength of live voice transmission, the squelch
    feature is defeated when Voice Mode is selected on
    the Data/Voice pin. The PSQ output always becomes
    inactive when the CH1840 is in Voice Mode. Note:
    When transmitting recorded or synthesized voice, the
    signal must be treated as Data per FCC; thus Data
    Mode must be selected on the Data/Voice pin.
    2-WIRE TO 4-WIRE CONVERTER
    This block has two functions: (1) it applies the XMIT
    signal to the phone line, (2) it subtracts this signal from
    Figure 3. Low Power Ring Detection
    the total signal on the phone to produce the received
    signal.
    The accuracy of this subtraction process
    For live voice or DTMF, when the CH1840 family
    depends on how closely the impedance of the phone
    products are in voice mode, the output can be 0 dBm.
    line matches 600 ohms. Generally, a small amount of
    In voice mode, the squelch will not let the output signal
    the XMIT signal will appear at RCV. The ratio of the
    exceed 0 dBm. Hence, by applying a 0dBm signal to
    XMIT signal applied to the signal returned is called
    the CH1840D and a +9.5 dBm signal to the CH1840, it
    trans-hybrid rejection. The CH1840 has a high trans-
    will achieve the maximum signal output.
    hybrid loss, which is at least 18dB rejection from 300
    Hz to 4 KHz bandwidth.
    CH1840 Family
    Normal Insertion Loss
    CH1840
    -9.5 dB
    CH1840D
    0 dB
    VOICE SIGNALS
    Voice signals are much more complex in nature than
    data signals. A voice signal is comprised of numerous
    The D designation refers to differential input between
    frequencies combined at varying intensities. Whereas
    the XMIT (+) and (-) pins. This is required and is a
    a data signal is comprised of no more than a few
    convenient input for certain types of modem ship sets.
    discreet frequencies.
    This difference dictates that
    voice signals receive more attention before connecting
    to the telephone lines.
    RECEIVE SIGNAL
    Receive Signal is presented at RCV with respect to
    The FCC restricts voice and data signals to between
    GND and must be AC coupled to your receive input.
    300 Hz and 3300Hz. This is because the Telephone
    The CH1840 does not add any gain to the receive
    Company uses frequencies below 300 Hz for low-
    signal. Receive signals can vary from a maximum
    speed tele type and frequencies above 3300 Hz for
    strength of 9dBm to below –50 dBm for data mode and
    internal signaling and multiplexing.
    up to 0 dBm strength when DTMF and live voice are
    being received.
    Data signals easily meet the FCC requirements
    without additional filtering. However, bandpass filters
    are essential for voice communication.
    EXCESSIVE SIGNAL DETECT
    FCC Part 68 rules limit the average power of data
    A bandpass filter is utilized on the transmit line. This
    signals transmitted to the phone line. To meet this
    filter ensures that the signal meets FCC requirements.
    requirement, the CH1840 monitors the transmit audio
    It also shapes the signal to minimize the phone line
    signal at XMIT. If the signal level exceeds 0 dBm.
    distortion.
    The output PSQ is normally LOW. It is set HIGH when
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    Document No. 607-0011 Revision B1 (09/04)
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    CH1840 Family of Low Profile DAA Modules
    Table 1.Pin descriptions
    Pin
    Name
    I/O
    Function
    1
    TIP
    I/O
    TIP . Direct connection to the telephone line through a standard jack.
    2
    RING
    I/O
    RING . Direct connection to the telephone line through a standard jack.
    3
    N/C
    -
    Not Used . Please leave unconnected
    4
    OFFHK
    I
    OFF HOOK , Input. When set LOW, the CH1840 is placed On-Hook. When set
    HIGH, the CH1840 is placed Off-Hook to answer or place a call. This input can also
    be used for pulse dialing.
    5
    RI
    O
    RING INDICATION , Output. RI is driven LOW during the typically 2 second ring
    period and HIGH during the typically 4 seconds between rings. RI is otherwise HIGH.
    NOTE: RI pulses square wave along with ring signal frequency. The square wave
    can be suppressed to produce an envelope of the AC ring with the application circuit
    shown in Figure 2.
    6
    D/V
    I
    DATA/VOICE SELECT , Input. When driven LOW or left unconnected, Data Mode is
    selected and the Billing Delay and Power Squelch are enabled. When driven HIGH,
    Voice Mode is selected and the Billing Delay and Power Squelch are disabled.
    7
    PSQ
    O
    POWER SQUELCH , Output. PSQ indicates the status of the signal limiting squelch
    circuit. When PSQ is HIGH, the transmit path is squelched. PSQ is also active when
    On-Hook and in Data Mode.
    8
    RCV
    O
    RECEIVE , Output. RCV is the audio signal received from the phone line. This output
    is symmetrical with respect to +2.5V. AC coupling is recommended for most designs.
    9
    XMIT(-)
    I
    Input must be used with pin 11 in differential mode only. When not used, please
    leave unconnected.
    10
    VCC
    I
    +5V Power Supply, Input.
    11
    XMIT(+)
    I
    TRANSMIT , Input. Analog signal input. Audio data and voice signals presented here
    will be monitored for excessive power, filtered through a bandpass, and applied to the
    phone line unless squelched. One input pin of two when used in differential mode
    with pin 9.
    12
    GND
    I
    SIGNAL AND POWER COMMON GROUND , Input.
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    CH1840 Family of Low Profile DAA Modules
    SAMPLE APPLICATION
    induced coupling with other signals on the host
    Figure 2 illustrates a typical application of the CH1840.
    circuit card.
    When transmitting data the controller must assert the
    D/V pin low to provide the two second billing delay
    5. The DAA Module is a sensitive subsystem that
    required by the FCC. When transmitting voice signals,
    should be treated as any other integrated
    the controller shoud drive the D/V pin high.
    This
    component.
    Pay special attention to the power
    disavles the billing delay, and power squelch
    supply to the DAA. The device handles signals in
    the millivolt range. Even though it is designed to
    One of the requirements of an FCC approved DAA is
    handle noise in the power supply, steps should be
    that the signal transmitted to Tip and Ring does not
    taken to assure the noise level does not exceed
    exceed –9.0 dBm.
    The Ch1840 incorporates an
    50mV peak-peak.
    automatic squelch
    6. For data calls, Part 68 rules require silence on the
    phone line for at least 2 seconds after a data call
    CH1840-D: 0 dB XMIT ATTENUATION
    has been completed to allow central offices to
    The D option has 0.0 dB insertion loss (typical) with
    exchange billing information and specifies the
    respect to a differential input between XMIT (-) and
    transmit level must not exceed -9dBm. The FCC
    XMIT (+). This allows the maximum signal strength of
    rules also require that for voice calls the final
    –9dBm to be input while maintaining FCC compliance.
    system meet the requirements of Part 68 for Out-of
    To use the CH1840-D as single end input device,
    Band
    Energy,
    and
    DTMF
    Transmit
    Levels.
    ground the XMIT (-) pin through a 0.1uF capacitor.
    Because
    the
    CH1840
    already
    meets
    FCC
    requirements for Part 68 registration for High
    Voltage isolation and Surge Protection, the
    MOUNTING THE DAA
    certification of the product is normally a simple
    The DAA can be soldered directly to the host circuit
    process that often can be completed directly with
    card or installed in sockets. To avoid the problems of
    the FCC. If desired, independent testing labs are
    contamination, hand soldering is preferred to wave
    available that can test the system and submit the
    soldering. When hand cleaning use only deionized
    required paperwork to the FCC for approval.
    water; when wave soldering use washless flux.
    Cermetek can assist with the registration.
    7. The CH1840 DAA as is meets or exceeds the
    DESIGN CONSIDERATIONS
    hazardous
    voltage,
    surge
    and
    leakage
    The CH1840 DAA includes circuits that couple the
    requirements of the FCC.
    For applications that
    modem signals to the phone line and provides FCC
    connect to Canadian phone lines, governed by the
    required
    isolation
    and
    protection.
    The
    FCC
    DOC (Department of Communications) and to
    registration process by the host product can be
    further protect the CH1840 from field failure on
    minimized provided that the following guidelines are
    excessively poor quality lines and to maintain UL
    followed.
    recognition, a higher level of transient protection is
    required, thereby making mandatory the circuit
    1. The mounting of the DAA in the final assembly
    consisting of two fuses and one varistor as shown
    must be made so that it is isolated from exposure to
    in Figure 3. Adding these three devices will not
    any hazardous voltages within the assembly.
    affect FCC registration. Components L1, L2, C1,
    Adequate separation and restraint of cables and
    C2 are optional and serve two purposes. First, they
    cords must be provided.
    restrict high frequency signals from reaching the
    phone line and thereby add EMI protection.
    2. Connection to the phone line should be made
    Second, they protect against externally generated
    through a standard FCC approved RJ-11C jack or
    RFI from degrading the modem’s ability to operate
    equivalent.
    on proper carrier signals. Adding these devices will
    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
    MOUNTING THE CH1840
    for this pacing is to maintain 1000 VAC isolation
    The CH1840 can be soldered directly to the host
    between the phone line and the other traces.
    circuit card or installed in sockets. Direct soldering
    Traces should have a nominal width of 0.020
    provides the most sound connection. To avoid the
    inches or greater.
    problems of flux contamination, hand soldering is
    preferred
    to
    wave
    soldering.
    Many
    socket
    4. TIP and RING traces should be as short as
    manufacturers offer socket strips that accept the 0.025
    possible and should be oriented to prevent direct or
    inch square pins on 0.10 inch centers. When using
    sockets mechanical restraint of the CH1840 should be
    2004 Cermetek Microelectronics, Inc.
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    Document No. 607-0011 Revision B1 (09/04)
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    CH1840 Family of Low Profile DAA Modules
    provided to keep it seated during shipment. Plastic
    (officially) serviced or returned for repairs. If upon
    cable wraps are secure yet easily removed.
    the above disconnection your regular service still
    has problems, notify your telco that they may have
    The DAA module contains static sensitive devices and
    a problem. Request prompt service at no cost to
    should be handled by personnel and in areas that are
    you the user. If a problem is found in premises
    properly protected against static discharge.
    wiring not telco installed, you are subject to a
    service charge. If a fault is in telco installed wiring,
    There
    are
    two
    mounting
    techniques
    that
    are
    you may be subject to a service call charge.
    recommended for physically connecting the module to
    your circuit card; 1) sockets, and 2) direct soldering.
    5) Unless otherwise noted in the User’s Manual (eg:
    Each approach has its own set of benefits and
    fuses,
    etc.),
    user
    may
    not
    under
    any
    challenges.
    circumstances (in or out of warranty) attempt any
    service, adjustments or repairs on this unit.
    It
    If the DAA module is wave soldered on a circuit card,
    must be returned to the factory or authorized U.S.
    please use washless flux or hand solder. This part is
    service agency for all such work. Locations (or
    not hermetically sealed. Water or chemical intrusion
    phone numbers) of factory or authorized U.S.
    into the case can cause malfunction and void the
    service points are listed in this user’s manual.
    warranty.
    6) Special FCC rules apply to equipment connected
    behind PBX or KTS.
    FOR YOUR USER’S MANUAL
    The Part 68 rules require the following or the
    7) Changes in Attestation Procedure for Plugs and
    equivalent information be provided to the end user of
    Jacks; (Name of Applicant) attests that the
    equipment containing a DAA:
    network interface plugs or jacks used on this
    equipment comply with and will continue to comply
    with the mechanical requirements specified in Part
    FCC NOTICE TO THE USERS
    68. Subpart F. Specifically the dimensions,
    1) UPON REQUEST ONLY, you must provide the
    tolerances and metallic plating requirements. The
    following data to your telephone utility company
    compliance of these connectors will be assured by
    (telco):
    purchase specifications and incoming inspections.
    a) Notice of intention to install or permanently
    Documentation of
    such specifications and/or
    remove an FCC Part 68 registered device or
    inspections will be provided the FCC within 30
    system, and the FCC Registration Number.
    days of their request for same.
    b) The Ringer Equivalence Number (REN) (see
    device label). Note that if several devices are
    connected to the same line, the RENs must
    not add up to more than 5.0 (A or B). This
    REN figure is important to your telco.
    c) The (USOC) jack type to be provided by telco.
    Typically this will be RJ-11C/W for single lines.
    *The *-flagged items above are noted on the
    equipments FCC Compliance Label.
    2) This device may not be used on telco-operated
    coin phone lines. Party lines and privately owned
    coin-phones are subject to local State regulatory
    policies, and possible additional State special
    requirements.
    3) The telco has the right to make changes to their
    network which may affect the operation of your
    equipment, provided you are given adequate
    advance written notice to permit correct operation.
    4) In cases of operational problems, disconnect your
    unit by removing the modular plug from the telco
    jack. If your regular phone (or other device or
    system) still works properly, your [product name]
    has a problem and must remain disconnected and
    2004 Cermetek Microelectronics, Inc.
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    Document No. 607-0011 Revision B1 (09/04)
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    CH1840 Family of Low Profile DAA Modules
    Figure 4
    Telephone Line Interface.
    1. RJ-11 Jacks must be provided by one of the
    B. For lightning prone areas where there are
    vendors on the list.
    Refer to Application Note
    more than 2 storms per year, provide an earth
    #130, Summary of Recommended Suppliers.
    ground connection and use a three terminal
    sidactor or similar device that provides metallic
    2. Current Line Device: F1 and F2 1.25amp.
    and longitudinal protection.
    This must also
    A. UL 1459 must use a current limit device. A
    include the current protection in Section 2.
    Poly Fuse is recommended as this device
    resets automatically after each power surge.
    4. EMI/RFI Suppression.
    The capacitor/ inductor network should be located
    B. Resistors (10ohm carbon film or SMD 1/8W
    as close to the RJ-11 Jack as possible with an
    minimum)
    may
    be
    used
    for
    non
    UL
    excellent ground path to the chassis. Capacitors
    applications.
    C1 and C2 should not exceed 0.005 µ F.
    They
    must have a rating of 1.5KV and typically have a
    3. Over Voltage and Lightning Protection.
    value of 0.001 µ F ± 20%. Inductors L1 and L2 are
    A. DOC (Canada) may require external current
    ferrite cylinders and provide attenuation to high
    limiting devices. Use 1ohm resistors (carbon
    frequencies
    from
    system
    level
    components
    film or SMD parts 1/8W minimum) in each lead
    external to the CH1840. The required values must
    (TIP and RING). You may substitute fuses or
    be empirically determined for each product design
    the Poly Fuse described in Section 2.
    2004 Cermetek Microelectronics, Inc.
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    Document No. 607-0011 Revision B1 (09/04)
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    CH1840 Family of Low Profile DAA Modules
    Table 2.
    CH1840 DAA Electrical Specifications.
    T A =0°C to 55°C unless otherwise specified
    Extended Temperature (ET) versions available for T A =-40°C to +85°C
    Parameter
    Symbol
    Conditions
    Min.
    Typ.
    Max.
    Units
    Logic
    Input HIGH
    V IH
    2.4
    V
    Input LOW
    V IL
    0.4
    V
    Input Leakage HIGH
    I IH
    500
    µ A
    Input Leakage LOW
    I IL
    -500
    µ A
    Output HIGH
    V OH
    IOH=0.2mA
    3.0
    V
    Output LOW
    V OL
    IOL=2.0mA
    0.4
    V
    Telephone Line Interface
    Z LINE
    600
    Ohms
    AC Impedance
    Isolation Protection
    Conforms to FCC Part 68 hazardous
    1K
    V RMS
    voltage and leakage
    Surge Protection
    Conforms to FCC Part 68 for surge
    800
    V Peak
    Transmit Level
    V TRX
    Measured at XMIT, 1800Hz
    CH1840
    0.774
    V RMS
    (Voice Mode) CH1840D
    0.251
    V RMS
    Transmission
    Insertion
    G TRX
    1800Hz, 600 Ohms, 35mA loop current
    Loss
    CH1840
    9.5
    10
    10.5
    dB
    (Voice Mode) CH1840D
    -9.5
    0.0
    0.5
    dB
    Receive Insertion Gain
    G RCV
    1800Hz, 600 Ohms, 35mA loop current
    -0.5
    0
    +0.5
    dB
    Trans-Hybrid Loss
    G TH
    600 Ohms+3& between TIP & RING
    18
    23
    dB
    600HZ to 4000Hz
    On-Hook Impedance
    Z ONHK
    OFFHK = 0 volts
    10
    20
    Mohm
    Loop Current
    ILOOP
    OFFHK = 5 volts
    20
    80
    mA
    Receive
    Output
    ZRNC
    Measured at RCV
    50
    Ohms
    Impedance
    Transmit
    Input
    Z TRX
    Measured at XMIT @ 1800Hz
    50
    100
    kOhm
    Impedance
    FCC Registration Number
    Supplied on unit label
    Ringer Equivalence
    REN
    Supplied on unit label
    0.2A
    REN
    TIMERS
    Ring Detection Delay
    T RGD
    Ringing at 40Hz, 45 V RMS
    200
    360
    ms
    Billing Delay Timer
    T BD
    20
    2.5
    30
    sec
    Hook Switch
    Drive capable of sourcing current
    4
    mA
    Power Supply Current
    V CC =+5VDC ± 5%, Off-Hook
    6
    10
    mA
    V CC =+5VDC ± 5%, On-Hook
    3
    6
    mA
    2004 Cermetek Microelectronics, Inc.
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    Document No. 607-0011 Revision B1 (09/04)
    Cermetek Microelectronics, Inc.
    CH1840 Family of Low Profile DAA Modules
    Figure 6. Pin Connections.
    Figure 7. Mechanical Specifications.
    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
    406 TASMAN DRIVE | 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
    iModem Network WEB SITE: http://www.imodem.net/ or https://sunnyvale.imodem.net/
    2004 Cermetek Microelectronics, Inc.
    Page 9
    Document No. 607-0011 Revision B1 (09/04)