CH1786ET_技术文档

CH1786 Family of Ultra Small

2400 bps Modems

Figure 1. Functional Block Diagram of CH1786.

INTRODUCTION

The CH1786 family of modems offer the smallest footprint

commercially available for a full function, FCC Part 68 approved

2400bps modem. These modems provide a fast, easy and flexible

way to integrate a modem into any OEM product while utilizing

the minimum amount of PCB space (1.0 ”x 1.25 ”x 0.53 ”). The

CH1786 family only requires two external interfaces: a CCITT

V.24 serial interface that can be routed directly to a UART, and a

Tip and Ring interface which goes directly to an RJ-11 jack for the

PSTN line connection. The CH1786 can be controlled with

industry standard AT commands and, hence, is compatible with

available industry communication software.

All CH1786 modems support asynchronous operation at

2400bps, 1200bps, and 300bps to both Bell and CCITT

standards. The resident PSTN line interface, or Data Access

Arrangement (DAA), while being FCC approved, is also Canadian

DOT approveable and can be approved in other countries that

require 1500VAC RMS isolation requirements per UL 1950.

The CH1786 family of modems operate off a single 5-volt supply.

The low power operation and automatic standby mode make

these modems ideally suited for portable equipment. In addition,

their small physical size affords maximum flexibility in equipment

design.

DESCRIPTION OF FUNCTIONAL BLOCKS AND

DISCUSSION OF BASIC OPERATIONS

Figure 1 contains a functional block drawing of the CH1786. The

CH1786 is a highly integrated, full-function modem, comprised of

a modulator/ demodulator, controller, NVRAM (Non-Volatile RAM)

and an FCC Part 68 approved PSTN line interface DAA (Data

Access Arrangement).

FEATURES

• Supports Standards CCITT V.22bis,V.22,Bell 212,and Bell 103

• FCC Part 68 approved and DOT CSA CS-03 Part I approveable

• UL 1950 and CSA C22.2 950 Listed

• AT Command structure with extensions

• 1500 VAC RMS isolation barrier minimum, 2122V peak surge

protection minimum

Modulation/Demodulation and Modem Controller.

These functions are provided by a monolithic modem integrated

circuit. This IC has built-in facilities to accommodate integrated

AT command control and contains the necessary resident

interfaces for general communication and routing to the DAA.

• Single 5 volt operation

• Low power operation with automatic reduced power standby

mode

• Automatic adaptive and fixed compromise equalization

• Test modes and diagnostics

• Size:1.0 ”x 1.25 ”x 0.53 ”(nominal)

• NVRAM allows storage of custom configurations and telephone

numbers

Telephone Line Interface or DAA.

The CH1786 family of modems is designed to meet 1500VAC

RMS isolation and provide 2122V peak surge protection.

Consequently, the CH1786 satisfies U.S. FCC Part 68 and DOT

CSA CS-03 Part I Canadian requirements, and will meet other

international approval agency requirements that specify these

levels of isolation.

CH1786 Family Includes:

CH1786LC

Operating

2400bps Modem, voice/ Inject, Hermetic

Figure 2. Voice/ Data Port Control

Temperature: 0°C to +70°C

CH1786NH

CH1786

2400bps Modem, No Voice/Inject, Non-hermetic

Operating Temperature: 0°C to +70°C

2400bps Modem, NVRAM, Voice/ Inject,

Operating Temperature: 0°C to +70°C

2400bps Modem, NVRAM, Voice/

Inject, Hermetic, Operating Temperature:

–40°C to +85°C

CH1786ET

CH1786FX

Same as CH1786 with send and receive

fax capability

The CH1786 comes with FCC Part 68 approval and is shipped

from the factory with an FCC Part 68 label indicating the

registration number and ringer equivalent. This label should be

prominently displayed on the end product.

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

With the exception of the U.S., most countries (including

Canada) require submission of the final product or system

containing the CH1786 to the appropriate governing

regulatory agency for approval. Typically this is accomplished

by submitting the final end product to an independent test

house or consultant for evaluation. The test house or

consultant then forwards the test results and applicable

documents to the regulatory agency. Call Cermetek for a list

of suggested consultants.

Sleep Mode.

To minimize power consumption, the CH1786 includes a power down

feature called Sleep Mode. When activated, the CH1786 will

automatically enter Sleep Mode after 0 to 254 seconds of inactivity.

The inactivity delay is selected using the ATS24 command. The

CH1786 is delivered from the factory with a 5 second inactivity delay

enabled (i.e., ATS24=5). The CH1786 returns to normal operation

when a ring signal is received or upon an input low signal on the TXD

pin. ATS24 = 255 disables the Sleep Mode and is the default if no

value is set in register S24.

Non-Volatile RAM (NVRAM).

A SLEEP output signal is available to control power to external

devices. In Figure 6, a FET controlled by the SLEEP signal turns of

the external speaker amplifier when the CH1786 enters Sleep Mode.

In Sleep Mode, power is reduced to approximately 50% of normal

operating power.

The NVRAM present on the CH1786 is sufficient to store up

to two user customized modem configurations. The AT&Wn

command will store the active modem configuration in the

selected NVRAM locations by specifying an n of 0 or 1.

The AT&Yn command selects the modem configurations to

be automatically recalled and made active upon a reset or

power up. The ATZn command immediately recalls and

activates a stored configuration. Refer to Tables 4, 5 and 6

for storable S-Registers and available commands.

Guard Tone.

A guard tone of 550 Hz or 1800 Hz can be generated at 6 dB or 9 dB

below the transmit level, respectively, by using the command &Gn.

Refer to “Cermetek AT Commands and S-Registers reference Guide”

or the Cermetek web site at http://www.cermetek.com

The NVRAM can save up to four telephone numbers with up

to 36 digits or modifiers in each telephone number. The

AT&Zn=s command will store s, the telephone number dial

string. The individual NVRAM telephone number storage

locations are selected by specifying an n of 0,1,2,or 3. The

ATDTS=n command will cause the modem to dial the stored

telephone number in location n. NVRAM is not available on

the CH1786LC or CH1786NH.

Answer Tone.

A CCITT (2100 Hz) or Bell (2225Hz) answer tone is generated

depending on the selected configuration. Refer to “Cermetek AT

commands and S-Registers Reference Guide” or the Cermetek web

site at http://www.cermetek.com.

Data Encoding.

The data encoding conforms to CCITT recommendations V.22 bis or

V.22, or Bell212A, or 103, depending on the selected configuration.

Refer to “Cermetek AT commands and S-Register Reference Guide”

or the Cermetek web site at http://www.cermetek.com

SUPPORT FEATURES

“AT ”Command Set.

A 40-character command line is supported. The command

line starts with AT and may contain standard or enhanced

Line Equalization.

commands.

The commands are compatible with EIA

Transmitter and receiver digital filters compensate for delay and

amplitude distortion during operation on nominal phone lines. In

addition, automatic adaptive equalization in the receiver minimizes the

effects of intersymbol interference.

Document TR302.2/88-08006.

Serial Host Interface.

The serial interface is a V.24 (EIA-232) compatible interface.

See pin description in Table 2.

Transmission Speed.

In normal operation, the originating modem initiates the call and

attempts to connect to the answering modem at a speed established

by the originating modem’s controller prior to call initiation. This is

referred to as the Initial Trained Rate. Upon receiving the call, the

answering modem will attempt to connect to the originating modem at

its Initial Trained Rate.

Speaker Interface.

The SPK output reflects the receiver analog input and

provides a signal that can be used to monitor call progress.

The SPK signal can drive a 300 W load directly. Typically, the

SPK signal is input into an audio power amplifier and the

amplifier, inturn, drives the speaker coil. The speaker is

activated with the ATMn command. The speaker volume is

adjusted using the ATLn command, where n is 0,1,2,or 3.

Increasing numbers correspond to higher volume. Figure 6

indicates one method of driving an external 8 W speaker.

If these two rates are identical, the connection is made. If the speeds

differ, the answering modem must adjust its rate or terminate the call.

Table 1 indicates the connection rate that will result when the calling

modem’s Initial Trained Rate and the answering modem’s Initial

Trained Rate are different.

Phone Control.

Cermetek s CH1786 contains a pin called Voice or Data

(V/D). The V/D pin toggles high when the modem goes off

hook. This pin can be used to activate a relay which can

switch a telephone on or off the Tip and Ring incoming PSTN

lines. This feature allows any telephone associated with the

CH1786 to be disconnected when a data call is in progress,

thereby preventing the data from being disturbed by an

inadvertent telephone pick-up. See Figure 2.

Note that a 2400 baud connection rate will only result if both modems

are initially set at 2400 baud.

Table 1. Connection Rates.

Speed and Parity Selection.

Prior to call initiation, the host controller trains the modem to

the host speed (2400,1200,or 300 bps) and parity (odd, even,

mark, space, or none)via a host-initiated training sequence.

This training also sets the speed of the data for originate

calls. The CH1786 will automatically adjust to the originator ’s

speed when answering calls.

The CH1786 matches the host ’s parity when it returns status

messages to the host. During a data connection, however,

the modem passes parity through without interpretation or

alteration.

2

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

Zero Power Mode (CH1786ET only).

When using the RI pin, it is recommended that a Schmitt Trigger or the

Isolated Envelope Detect Circuit in Figures 3 or 5 be placed between

the RI pin and the external load.

If an application calls for zero power during standby periods,

the power may be switched off using external circuitry and

then reapplied when the CH1786 ’s RI pin becomes active.

The CH1786ET products can thus be powered down to zero.

Power Supply.

The CH1786 modem module is a complex set of sub-systems. During

the course of normal operation the CH1786 decodes analog signals

from the telephone line that are in the millivolt range. Steps must be

taken by the user to guarantee that power supply noise on all supply

lines, including ground, does not exceed 50 mV peak to peak. Any

frequency between 20 kHz and 150 kHz must be less than 500 micro

volts peak. If necessary, use dedicated power and ground planes.

Failure to provide such operating conditions could cause the CH1786 to

malfunction or to function erratically.

Figure 3. Zero Power Operation

The CH1786 requires a single +5V ±5%supply. It is recommended that

by-pass capacitors be placed on the power supply as close to the

modem’s supply input as practical. It’s recommended a 10 mF Tantalum

capacitor in parallel with a 0.01 µF ceramic capacitor be used.

Voice/ Tone Injection Port.

The CH1786 provides two pins to allow the user to share the telephone

line interface associated with the modem for voice and DTMF

applications. Figure 4 contains a schematic indicating one possible

configuration for voice/ tone utilization.

WARNING: The CH1786 has been FCC Part 68 approved as a data

modem only. Utilization of the Voice/Tone Port requires further

registration. FCC will require that the system , including the

CH1786 and the handset or DTMF transceiver, adhere to Part 68

rules. Voice/Tone Injection is not active on CH1786NH.

Referring to Figure 3, the controller activates the relay switch,

supplying power (+5V to the CH1786ET-UL.

In this

configuration, the ring signal is used to “wake up ”the

CH1786ET-UL when the CH1786ET-UL is in the power down

state.

Figure 4. Voice/ Tone Injection

The pins of the CH1786ET-UL will be in an undefined state

when power is switched off. This must be taken into

consideration to assure that no unwanted signals are

presented to the CH1786ET-UL during power down.

Ring Indicator (RI).

The RI pin follows the frequency of the ring signal and toggles

low when the CH1786 detects an incoming call. The ring

signal is typically 20 to 30 Hz and is on for 2 seconds and off

for 4 seconds. Although not TTL compliant, the RI pin can,

nonetheless, be utilized to activate external circuitry including

the external RST pin.

Typically, voice communication would precede data communications.

For this case, the following commands should be used to configure the

CH1786 (Refer to Figure 4):

Enter: ATS0=[CR]

Enter: ATS7=255[CR]

Enter: ATS10=255[CR]

Disables auto-answer

Eliminates hang-up due to

lack of carrier signal.

The following command sequences illustrate implementation of

common Voice/Tone Port applications.

1. To answer a voice call:

(a) Enter: ATH1[CR]

(b) Drive V.INJ. HIGH to activate relay.

(c) Begin voice conversation.

2. To switch to data mode, drive V.INJ. LOW, then:

(a) At the originate modem:

Enter: ATX1[CR]

3. To disconnect (hang-up) a voice call or a data call:

Enter: ATH[CR]

4. To place a call using the CH1786’s DTMF:

(a) Enter ATDT#;C0[CR]

(b) Drive V.INJ high

3

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

Figure 5. CH1786 Application Diagram

Table 2. CH1786 Pin Descriptions

FUNCTION

NAME

TYPE

Directly connects to the telephone line’s Ring lead through a user supplied RJ-11C jack.

Directly connects to the telephone line’s Tip lead through a user supplied RJ-11C jack.

ANALOG VOICE INJECTED. Receive Signal. Let float if not used. Not active in CH1786NH.

ANALOG VOICE INJECTED. Transmit Signal. Let float if not used. Not active in CH1786NH.

1

RING

I/O

2

3

4

TIP

RXA

TXA

I/O

O

I

4

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

Table 2. CH1786 Pin Descriptions (Continued)

SPEAKER. Audio output for speaker. See speaker control schematic in Figure 6.

5

6

SPK

NC

O

-

No connection.

7

8

NC

-

SLEEP output. A LOW indicates CH1786 is in low power idle mode. Used to control power to

other devices. See Figure 6. Register S24 is the sleep timer register. When the CH1786 is

inactive for a period of time specified by S24, the CH1786 will power down by about 50% of its

normal operating power. During power down, all I/O lines become undefined. The CH1786

products are shipped from the factory with a 5 second inactivity timer (ATS24=5) enabled.

SLEEP

O

No connection.

9

NC

-

I

TRANSMIT DATA. Serial Transmit data input. Marking or a binary 1 condition is transmitted

when a HIGH is asserted.

10

TXD

RECEIVE DATA. Serial Receive data output. Received marking or binary 1 condition is

indicated by HIGH.

11

12

RXD

V/D

O

Voice/Data output is used to switch between telephone and modem line use. In a typical

application, V/D active HIGH opens the normally closed voice injection relay and disconnects

the handset from the telephone line. See Figure 2.

DATA TERMINAL READY input. Active LOW. Switching off DTR can either return modem to

command state, disconnect phone call, or reset modem. DET should be set LOW when not

used.

13

DTR

I

DATA SET READY output. LOW indicates handshaking with a remote modem is in progress,

and/ or the data carrier of a remote modem has been detected.

14

15

DSR

RI

O

RING INDICATION. This signal follows the frequency of the ringing signal and is normally

about 20 to 40 Hz for 2 seconds on with 4 seconds off.

CLEAR-TO SEND. Output always LOW. Reserved for flow control when using FAX option.

Currently, CTS only active on CH1786FX when S24=255. No power down mode option

available. Effective 31 May 2000, CTS will be active on CH1786 also.

16

CTS

O

DATA CARRIER DETECT. LOW indicates a data carrier from a remote modem is detected.

17

18

DCD

HS

O

SPEED INDICATION. HIGH speed select output. A low on this pin indicates the modem is

operating at 2400bps.

POWER SUPPLY. 5 volts + 5% Note: Noise should be less than 50mV peak to peak.

GROUND. Note: Noise should be less than 50mV peak to peak.

19

20

21

VCC

GND

RST¹

-

I

RESET input. Active HIGH. This input must be asserted HIGH for at least 10 ms to reset the

modem. RESET is then returned LOW for normal operation. If no system reset is available, let

this pin float to enable internal reset.

No connection.

22

NC

-

Note: (1) If VCC has a slow power up ramp time, the internal reset may be ineffective.

ã 2000 Cermetek Microelectronics, Inc. Document No. 607-0004 ECN 8176 Rev. H (03/00)

5

MODEM CONTROL

AT [commands] [CR].

The CH1786 modem may be controlled by sending serial

ASCII command sequences. The commands are sent to the

modem serially on the TXD pin. After execution of a received

command, the modem returns a serial status message that can

be read on pin RXD. This message indicates command com-

pletion status. Refer to Table 3 for a complete list of status

messages.

Where: AT represents attention sequence.

[commands ] represents command strings.

[CR ] represents carriage return (ASCII 13 or HEX 0D).

When entering commands to the modem, the backspace charac-

ter-control-H (ASCII 8 or HEX 08)can be used to edit mistakes.

“AT ”and “A/”may not be edited however. Multiple commands

may be placed in the command line. A command line may be as

long as 40 characters, excluding the letters AT. By way of

example, the command below instructs the CH1786 to configure

itself to not echo characters when in command mode (E0)and

then put itself in answer mode (A).

INITIALIZING THE MODEM

Before commands may be sent to the CH1786,the modem

must be initialized. This consists of two events:

1) Reset .This is accomplished by applying a hardware reset

pulse to pin RST or by switching the power off and then back

on.

Enter:ATE0A [CR ]

2) Initial modem training. The modem must be trained to the

host ’s speed (2400,1200,300bps) and parity (odd, even, mark,

space or none).

AT Command Set.

The available command set is divided into four types of com-

mands: dial modifiers, basic commands, ampersand and percent

commands. Refer to the complete list in Table 5.

These activities are briefly described below.

Reset.

AT Command Data Rate.

Upon applying power to the CH1786, the CH1786 auto-

matically generates an internal reset pulse. The user can also

reset the modem externally by applying a high-going reset

pulse to the RST pin for at least 10ms after the +5V power

supply has stabilized. Delay sending commands to CH1786

for 200ms after reset has been initiated to allow the CH1786

time to properly reconfigure.

With the serial interface, the rate is speed sensed for parity and

format.

THE STATUS MESSAGES

The CH1786 responds with a status message after each com-

mand is executed. This status message may either be a single

digit followed by a carriage return or a carriage return and line

feed with a message in English, followed by a carriage return and

line feed.

Training the Modem.

Each modem must be trained to match its host ’s speed and

parity so that it is able to recognize serial asynchronous

commands sent to it by the host UART. The host must retrain

the modem each time a reset pulse is applied on RST or after

a RESET serial command has been issued.

The basic status code subsets are enabled with the Xn com-

mand. Where n=0,1,2,3,4 establishes the result codes allowed

by the user.

X0 -Result Codes 0, 1, 2, 3, 4 allowed

X1 -Result Codes 0, 1, 2, 3, 4, 5, 10 allowed

X2 -Result Codes 0,1, 2, 3, 4, 5, 6, 10 allowed

X3 -Result Codes 0, 1, 2, 3, 4, 5, 7, 10 allowed

X4 -Result Codes 0, 1, 2, 3, 4, 5, 6, 7, 10 allowed

Modem Training Command Sequence.

The CH1786 is trained by sending it the following sequence:

Enter: AT [CR ]

Where: A and T may be either upper or lower case but must

The CH1786 is factory set to X4, which allows all result codes.

be the same case.

[CR ] represents carriage return

Table 3. Summary of Result Codes and Meanings.

The “AT” sequence is referred to as an attention

sequence. The CH1786 will respond with one of the

following status messages, depending on whether it is

optioned for abbreviated or English status messages.

Result: 0 [CR ]

(Abbreviated form)

Result: [CR ][LF ] OK [CR ][LF ] English form)

Where: [CR ] represents carriage return (ASCII 13 or HEX

0D).

[LF ] represents line feed (ASCII 10 or HEX 0A).

The modem is now in idle mode and is ready to accept com-

mands. An alternate attention sequence “A/”may be sent

which behaves much like the AT sequence except that it

causes the previously entered command specified with an AT

prefix to be executed. When given, it must be in upper case

ASCII. No carriage return is needed.

THE COMMAND FORMAT

Typical commands consist of three elements: the attention

sequence, the commands themselves, and a terminating

carriage return.

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ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

Table 4. CH1786 Register Summary

Table 5. CH1786 “AT” Command Set Summary

Register

S0*

S1

Function

Ring to Answer On

Ring Count

Basic Commands

AT

A

Function

Attention Code

Answer command

Escape Code Character

Carriage Return Character

Line Feed Character

Back Space Character

Wait for Dial tone

Wait for Data Carrier

Pause Time for Comma

Carrier Detect Response Time

Lost Carrier to Hang-up Delay

DTMF Dialing Speed

Escape Code Guard Time

Bit Mapped Options Register

Modem Test Options

Repeat last Command

Communications Standard Option

Dial Command

Off-Line Character Echo Option

Switch Hook Control Option

Speaker Volume Option

Speaker Control Option

On-Line Command

S2

S3

S4

S5

S6

S7

S8

S9

S10

S11

S12

S14*

S16

S18*

S21*

S22*

S23*

S24

S25*

S27*

S28*

A/

*BN

D

*E

Hn

*Ln

*Mn

On

P

*Qn

Sn

Sn=

Sn?

*Vn

*Xn

+++

,

Pulse Dial

Result Code Display Option

Select an S Register

Write to an S Register

Read an S Register

Result code Form Option

Result Code Set/Call Progress Option

Escape Code Sequence Pause

Pause

Returns Last addressed S Register

Long Space Disconnect Option

On Line Echo character Option

Reset

Test Timer

Bit Mapped Options Register

Sleep Mode Inactivity Time

Delay to DTR

?

*Yn

Fn

Bit Mapped Options Register

Z

*=S-Registers stored in NVRAM upon receipt of &W command

Table 6. Fax Command Set Summary

Fax Command

+FCLASS=n

+F<command>?

+F<command>=?

+FAA=n

+FF

+FTS=n

Function

Select Service Class

Dial Modifiers

P

R

T

W

;

@

!

Function

Pulse Dial

Report Active Configuration

Report Operating Capabilities

Data/Fax Auto Answer

Enhanced Flow Control

Stop Transmission and Wait

Transmit Data

Originate Call in Answer Mode

Touch Tone Dial

Wait for Dial Tone

Return to Idle State

Wait for Quiet Answer Command

Flash Hook

+FTSM=n

+FTH=n

Receive Data

,

Paul

+FTH=n

Transmit Data with HDLC Framing

0-9

Dial Digits/Characters

+FRH=n

Receive Data with HDLC Framing

A,B,C,D

+FRT=n

Receive Test Data

Transmit test Data

+FTTn=m

Ampersand Commands Function

*&Cn

Data Carrier Detect Option

MODEM STATES

The CH1786 can be in either command mode or data mode.

When the modem is idle, it is in command mode by default and

will recognize commands. When data transmission is in

progress, the CH1786 is in the data mode state and will not

recognize commands. To force the CH1786 to recognize

commands, the host must send an “escape sequence ” to the

CH1786 forcing it out of data mode and into command mode.

*&Dn

&F

*&Gn

*&Pn

*&Sn

&Tn

Data Terminal Ready Option

Load Factory Defaults

Guard tone Option

Make to Break Ratio Selection

Data Set Ready Option

Test Command Option

View Active Configuration

Store active profile

&V

*&Wn

*&Yn

*&Zn

The escape sequence consists of a “guard time” (a period

where no characters are sent to the modem), followed by 3

escape characters, followed by another guard time. At power-

up, the guard time is set to 1 second minimum, and the escape

character is set as “+.” These two parameters can be modified

via registers S12 and S2, respectively.

Recall active profile

Store telephone numbers

Percent Commands

%Dn

%J

Function

DTMF Attenuation

Load Secondary Factory Defaults

The CH1786 will stay off-hook with its carrier on after the

escape sequence is received and it returns an OK status

message when it is ready to accept commands. The CH1786

can be put into data mode by issuing the command ATO [CR ].

*=Commands that can be stored in NVRAM. Not supported by the

CH1786LC or CH1786NH.

NOTE: A detailed definition of all commands and registers is

available from Cermetek Microelectronics, Inc. Refer to

Cermetek Document “AT Commands and S-Registers

Reference Guide” or access our web site at

www.cermetek.com.

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ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

S0 =0 DO NOT ANSWER TELEPHONE

S0 =1 ANSWER ON RING 1

S0 =2 ANSWER ON RING 2

S0 =3 ANSWER ON RING 3

S0 =255 ANSWER ON RING 255

When S0 is set to 0,the modem will not auto-answer.

AT COMMAND APPLICATIONS

Dialing A Phone Number.

The Dial command takes the form Dn, where n is a string of char-

acters. In the simplest form, n will be only the digits of the phone

number to be dialed.

Example: Dial number.

Enter: AT D1234567

The Serial Interface Lines.

The CH1786 supports a full EIA-232D/V.24 serial interface.

Signal levels are TTL rather than EIA-232D level com-

patible, which allows direct connection of the CH1786 to

the host UART without level translating circuitry. See

Table 2 for a complete pin description.

In response to this command, the CH1786 dials the telephone

number “123-4567 ” and then waits for a carrier from the distant

modem. If no carrier is detected within a given time (the default

time is 30 seconds),the CH1786 automatically releases the line

and sends a NO CARRIER result code. If a carrier is detected,

the CH1786 gives a CONNECT result code and goes on-line,

permit-ting communication with the distant modem.

The modem is controlled by sending it serial commands

over TXD and can be monitored by serial status messages

returned on RXD. DTR is optionally used to reset, ter-

minate calls or return CH1786 to command mode.

The Dial Command may also be issued without a telephone

number. ATD causes the modem to pick up the telephone line

without dialing a number.

All other serial interface lines may be utilized for the con-

venience of a particular application but are not required by

the CH1786. Unused outputs (from modem)should be left

unconnected. Unused inputs should be set to the proper

logic level. See Table 2.

Pause During Dialing.

When placing a call from an office with a telephone connected to

a PBX, it may be necessary to dial an access code (usually the

digit 9) to get an outside line. Inserting a comma in the telephone

number instructs the modem to pause for a specific length of

time. The factory set default pause time is 2 seconds.

FAX MODES (CH1786FX only)*

The CH1786FX supports Send and Receive Fax in addition

to the modem functions as defined by CH1786.

Example: Dial 9,pause, dial number.

Enter: AT DT9,1234567

FAX modes and rates are determined by the AT+F

commands. Refer to Table 6.

Multiple commas may be used to generate integer multiples of

the specified delay time.

FAX modem processing is explicitly defined in CCITTV.29,

CCITTV.27, and CCITT V.21 recommendations. All mo-

dulation, wave-form spectrum, and data processing func-

tions conform to the appropriate specifications.

Originate a Call in Answer Mode.

The D command forces the modem into originate mode. To call

an originate-only modem, dial the number and set the modem to

answer mode via the R command (reverse originate). This is

done by including an R at the end of the telephone number.

For additional information on CCITT recommendations,

contact Omnicom, Tel: 703-281-1135 or see CONEXANT’s

RC224ATF Designer ’s Guide, Tel: 714-221-4600.

Example: Change modem from original-only to answer mode.

Enter: AT DT 1234567R

Figure 6. Speaker Control Circuit— optional to

allow for call progress monitoring.

Redial Last Number.

Use A/, the repeat command, to redial the last telephone number

dialed.

Return to Command State.

Example: Touch-tone dial 9, pause, dial number, return for Com-

mand.

Example: Touch-tone dial 9, pause, dial number, return for

command.

Enter:

Result:

AT DT9,1234567;

OK

Automatic Answering.

The S0 register controls the number of rings that must occur

before the modem answers a call. The register may range in

value from 0 to 255.

*Note: Currently the CH1786FX product performs the FAX function while the CH1786 does not. Special order version of the CH1786 are

available upon request that perform both data and FAX functions. Effective May 31, 2000 only the combined Data + FAX CH1786 will be

available.

8

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

PHONE LINE CONNECTION GUIDELINES

CH1786 HANDLING AND ASSEMBLY

RECOMMENDATIONS

1) The CH1786 must be mounted in the final assembly such that

it is isolated from exposure to any hazardous voltages within the

assembly. Adequate separation and restraint of cables and cords

must be provided.

2) The circuitry from the CH1786 to the telephone line interface

must be provided in wiring that carries no other circuitry other

than that specifically allowed in the FCC rules (such as A and A1

leads).

The CH1786 contains static-sensitive components and should only

be handled by personnel and in areas that are properly protected

against static discharge. There are two mounting techniques that

are recommended for physically connecting the CH1786 to a

PCB:1)sockets, and 2) direct soldering.

Direct Soldering.

The CH1786 may be wave soldered onto a circuit card. All

CH1786 products are hermetically sealed (except

CH1786NH) and will not be harmed by industry standard wave

soldering processes. Cermetek recommends against exposing the

non-hermetic CH1786NH to aqueous based rinsing processes.

3) Connection to phone line should be made through an RJ-11C

jack.

the

4) PCB traces from the modem’s RING and TIP pins to the RJ-

11C jack must be 0.1 inch spacing or greater to one another and

0.2 inch spacing or greater to all other traces. The traces should

have a nominal width of 0.020 inches or greater.

5) The RING and TIP PCB traces should be as short as possible

and oriented to prevent coupling other high speed or high fre-

quency signals present on the host circuit PCB.

6) No additional circuitry other than that shown in Figure 7A or

7B may be connected between the modem module and the RJ-

11C jack. Doing so will invalidate the FCC approval.

7) The CH1786LC (only)requires external surge protection (see

Figure 7B).This is mandatory to maintain FCC Part 68 conveyed

approval.

Socketing.

The socketing approach to mounting eliminates cleaning and

desoldering concerns. When the socket is used, it must make a

solid connection to all pins. Failure to do so will cause unreliable

or intermittent operation. Also, steps should be taken to assure

that the module remains tightly seated in the socket after the end

product is shipped. Cermetek recommends socket CES-150-01-T-

S by Samtec, 50 pin strip socket.

8) The CH1786,the RJ-11C jack, the interfacing circuitry and all

PCB traces in between, must be contained on a PCB with a 94 V-

0 flammability rating.

9) The supplied FCC registration label must be applied visibly on

the outside of the product.

10) The product ’s User Manual must provide the user with in-

structions for connection and use as recommended in the FCC

Registration Section below.

Figure 7A. PSTN Line Interface for CH1786 Family (except CH1786LC and CH1786NH).

9

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

Figure 7B. PSTN Line Interface for CH1786LC and CH1786NH only.

FCC REGISTRATION

Telephone Company Procedures: The goal of the

telephone company is to provide you with the best service it

can. In order to do this, it may occasionally be necessary for

them to make changes in their equipment, operations or

procedures. If theses changes might affect your service or

the operation of your equipment, the telephone company will

give you notice, in writing, to allow you to make any changes

necessary to maintain uninterrupted service.

All products in the CH1786 family are registered with the FCC

(Federal Communications Commission) under Part 68. To

maintain the validity of the registration, you must serve notice

to the end user of the products of several restrictions the FCC

places on the modem and its use.

In addition to restriction notification, the FCC requires that

Cermetek make all repairs to all products in the CH1786

family. If repairs are necessary after installation of the

CH1786 in the end product and the end product has been

delivered to theend user, the end product must be returned to

the end product supplier where the CH1786 can be removed

and then forward to Cermetek for repair. The following notice

is recommended and should be included in the end product’s

user manual.

In certain circumstances, it may be necessary for the

telephone company to request information from you

concerning the equipment which you have connected to

your telephone line.

Upon request of the telephone

company, provide the FCC registration number and the

ringer equivalence number (REN); both of these items are

listed on the equipment label. The sum of all of the REN’s

on your telephone lines should be less than five in order to

assure proper service from the telephone company. In

some cases, a sum of five may not be useable on given line.

Consult your telephone provider.

FOR YOUR USER’S MANUAL

The part 68 rules require the following (or equivalent) be

provided to the end user of equipment containing a DAA:

If Problems Arise: If any of your telephone equipment is not

operating properly, you should immediately remove it from

your telephone line, as it may cause harm to the telephone

network. If the telephone company notes a problem, they

may temporarily discontinue service. When practical, they

will notify you in advance of this disconnection. If advance

notice is not feasible, you will be notified as soon as

possible.

Type of Service: The (insert end product name) is designed to

be used on standard device telephone lines. It connects tot he

telephone line by means of a standard jack called the USOC

RJ-11C (or USOC RJ45S).

Connection to telephone-

company-provided coin service (central office implemented

systems) is prohibited. Connection to party lines service is

subject to state tariffs.

Changes in Attestation Procedure for Plugs and

When you are notified, you will be given the opportunity to

correct the problem and informed of your fight to file a

complaint with the FCC. Contact your local telephone

service provider if you have nay questions about your phone

line.

Jacks. (Name of applicant) attests that the network interface

plugs or jacks used on this equipment comply with and will

continue to comply with the mechanical requirements specified

in Part 58, sub-part F, specifically the dimensions, tolerances

and metallic plating requirements. The compliance of these

connectors will be assured by purchase specifications and

incoming inspection. Documentation of such specifications

and/ or inspections will be provided to the FCC within 30 days

of their request for the same.

10

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

In the event repairs are ever needed on the (insert your product

name),they should be performed by (insert your company name)

or an authorized representative of (insert your company name).

For information contact:(insert your company address).

DEFAULT STATUS, PERFORMANCE, AND SPECS

The following is a summary of the Default Configuration

Profile installed by Cermetek Microelectronics, Inc prior to

delivery of the CH1786.

Async mode selected

2400bps

Bell 212A operation at 1200bps

Even parity

Auto answer enabled (Disabled on CH1786NH)

Command echo ON

All result codes enabled –extended

Wait for dial tone before dialing =2 seconds

Detects busy signal

Full word result codes

Pulse dial make/break ratio =39/61

DSR enabled

Modem enabled DTR (Disabled on CH1786NH)

DCD enabled (Disabled on CH1786NH)

Speaker enabled but off when receiving carrier

Speaker volume set to medium

Local modem will grant RDL request from remote modem

Guard tones disabled

Minimum DTR pulse width =0.1 seconds

Ring count =01 (CH1786)

Escape code character =43

Carriage return character =13

Line feed character =10

Back space character =08

Duration of wait for dial tone =02 seconds

Duration of wait for carrier after dialing =30 seconds

Duration of dial pulse (comma)=02 seconds

Carrier detect response time =0.1 seconds

Escape code guard time =1 second

Length of use after comma =2.0 seconds

Last carrier to hang up delay =0.1 seconds

DTMF interdigit delay =0.1 seconds

DTMF Attenuation =-4dB

Sleep mode inactivity time =5 seconds

Long space disconnect disabled

11

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

Table 7. CH1786 System Data Mode Compatibility Specifications

Table 8. CH1786 Electrical Specifications

12

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

Table 9. CH1786 Electrical Specifications

Parameter

Minimum

20

Typical

25

Maximum

Units

Ohm

dB

Comments

Off Hook Impedance

Trans Hybrid Loss

Ring Voltage Loop

600 Ohm, RXA, TXA

On 48VDC line voltage

for sustained periods

110V

250V

100

V_pp

Line Loop Current – (Off-Hook)

Return Loss @ 1000 Hz

Ring Frequencies

20

15

mA

dB

600 Ohm

40

Hz

Receiver Insertion Gain

Transmit Power

-0.5

0.0

-9.5

1.0

50

+0.5

5

dBm

dB

600 Ohm – Data Mode

First Character After Reset

Inter Character Delay

0.5

20

sec

msec

Delay

Between all command

characters

Command Delay

100

10

200

msec

Between all AT

commands

Minimum Reset Pulse Duration

If user supplied

Table 10. Other Performance Specifications

Parameter

Min.

Typ.

Max Unit

s

Comments

Tone 2^ndHarmonic Distortion

DTMF Twist (Balance)

DTMF Tone Duration

-35

dB

ms

pps

%

HYB enabled into 600W

3

50

8

255

20

95 ms default

Pulse Dialing Rate

10

10pps default

Pulse Dialing Make/ Break

Pulse Interdigit Interval

Guard Tone Frequency

Guard Tone Amplitude

Guard Tone Frequency

Guard Tone Amplitude

High Channel Transmit Amplitude

39/61

33/67

US, Canada default

%

UK, Hong Kong

700

3000

ms

Hz

dB

Hz

dB

789 ms default

550

-6

Referenced to High Channel Transmit

1800

-9

-1

Referenced to Low channel, Guard tone

enabled

Guard Tone 2^ndHarmonic Distortion

Call Progress Passband Frequency

Wait Time for Dial tone

-40

dB

Hz

120

2

620

255

sec

dB

Two second default

Return loss @ 1000 Hz

30

T_r= 600 W + 2.16 m F

Table 11. Analog Characteristics

Name

Type

Characteristic

Value

SPK

O(DF)

Minimum Load

300W

0.01m

10W

Maximum capacitive Load

Output Impedance

Output voltage

2.5 + 1.6V

D.C. Offset

<20mV

13

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)

Table 12. Summary CH1786 Family of Products

Summary of Features

Model

Operating Temperature

0° C to 70°C

CH1786LC

CH1786NH

CH1786

Full function, Voice/ Inject, FCC Part 68 Approved, UL 1950

Listed, Hermetic

Full Function, No Voice/Inject, FCC Part 68 Approved, Non-

Hermetic, UL1950 Listed

0° C to 70°C

Full Function, NVRAM, FCC Part 68 approved, UL1950 Listed,

0° C to 70°C

Hermetic

CH1786ET

CH1786FX

Full Function, NVRAM, Zero Power Option, FCC Part 68

Approved, UL1950 Listed, Hermetic

Full Function + FAX, NVRAM, FCC Part 68 Approved,

-40° C to 85°C

0° C to 70°C

Hermetic, UL1950 Listed.

Currently, both UL1459 and UL1950 Listed versions are available. Effective 31 May 2000, the higher

performance UL1950 versions will become standard. Additionally, effective 31 May 2000, the combined data +

FAX functions will become standard on the CH1786 thereby obsoleting the CH1786FX.

Figure 8. CH1786 Physical Dimensions and Pin Functions

PACKAGE CONNECTION TABLE

PIN NO.

FUNCTION

PIN NO.

FUNCTION

1

2

3

4

5

6

7

8

9

RING

TIP

RXA

TXA

SPK

NC

SLEEP

NC

12

13

14

15

16

17

18

19

20

21

22

V/D

DTR

DSR

RI

CTS

DCD

HS

VCC

GND

RST

NC

10

11

TXD

RXD

1. All dimensions are in inches.

2. Case dimensions are nominal + 0.02 inches.

3. Pin length is nominal + 0.03 inches.

4. Cermetek recommends that 0.04 inch diameter plated through holes are used with 0.060 inch diameter pads.

5. Pin spacings are nominal.

6. CH1786NH has four 15mil round, 15mil high standoffs on the bottom of the package.

*If a low profile version of the CH1786 is required, please see the CH2000.

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, no responsibility is assumed by Cermetek 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.

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

WEB SITE: http://www.cermetek.com | EMAIL: sales@cermetek.com

14

ã 2000 Cermetek Microelectronics, Inc.

Document No. 607-0004 ECN 8176 Rev. H (03/00)


型号：	CH1786ET
厂家：	ETC
描述：	MODEM MODEM\n
文件：	总14页 (文件大小：1182K)
中文：	中文翻译
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