CH1786_技术文档

CH1786 Family of Ultra Small 2400bps Modems

INTRODUCTION

FEATURES

The CH1786 family of modems are 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 (1.01 ”x

1.27 ”x 0.52 ”). 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

• Supports Standards CCITT V.22bis,V.22,Bell

212,and Bell 103

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

approvable

• UL 1950 and CSA C22.2 950 Listed

• UL File Number: E104957

• AT Command structure with extensions

• 1500 VAC RMS isolation barrier minimum, 2122V

PSTN line connection.

The CH1786 can be

peak surge protection minimum

controlled with industry standard AT commands and,

hence, is compatible with available industry

communication software.

• Single 5 volt operation

• Low power operation with automatic reduced power

standby mode

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 approvable and can

be approved in other countries that require 1500VAC

RMS isolation requirements per UL 1950 Edition 3.

• Automatic adaptive and fixed compromise

equalization

• Size: 1.01 ”x 1.27 ”x 0.52 ”(nominal)

• NVRAM allows storage of custom configurations

and telephone numbers

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.

CH1786 FAMILY

CH1786

NVRAM, Voice/ Inject, Hermetic,

Operating Temperature:

0°C to +70°C

CH1786ET

CH1786NH

NVRAM, Voice/ Inject, Hermetic,

Operating Temperature:

-40°C to +85°C

Non-Hermetic, Operating

Temperature:

0°C to +70°C

Figure 1. Functional Block Diagram of CH1786.

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.

Figure 2. Voice/ Data Port Control

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Document No. 607-0004 Revision L1 (06/03)

Cermetek Microelectronics, Inc.

CH1786 Family of Ultra Small 2400bps Modems

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-

SUPPORT FEATURES

AT Command Set. A 40-character command line is

supported. The command line starts with AT and

may contain standard or enhanced commands. The

commands are compatible with EIA Document

TR302.2/88-08006.

function modem, comprised of

a

modulator/

demodulator, controller, NVRAM and an FCC Part 68

approved and UL 1950/CSA C22.2 950 listed PSTN

line interface.

Serial Host Interface. The serial interface is a V.24

(EIA-232) compatible interface. Ten Bits total: 1 start

bit, 1 stop bit, and eight data bits which can be either

eight bits with no parity or seven odd or even with

parity. The start bit is LOW going. RXD and TXD

data is non-inverted. See pin description in Table 2.

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.

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 Ω load directly. Typically, the SPK signal

is input into an audio power amplifier and the

amplifier, in turn, 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 Ω speaker.

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.

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

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.

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.

Non-Volatile RAM (NVRAM). 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.

Speed and Parity Selection. Prior to call initiation,

the host controller trains the modem to the host

speed (2400,1200 or 300bps) 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

The AT&Yn command selects the modem

automatically adjust to the originator’s speed when

answering calls.

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.

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.

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

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

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.

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

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CH1786 Family of Ultra Small 2400bps Modems

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.

pin becomes active. The CH1786ET products can

thus be powered down to zero.

Table 1. Connection Rates.

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.

Answering

Modem Initial

Trained Rate

Connection Rate Resulting

When Calling Modem Initial

Rate Is:

300

1200

2400

1200

2400

300

1200

2400

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 &Gn command. Refer to

“Cermetek AT Commands and S-Registers reference

Guide”

or

the

Cermetek

web

site

at

http://www.cermetek.com.

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.22bis 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.

Line Equalization. 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 inter symbol interference.

Figure 3. Zero Power Operation.

Referring to Figure 3, the controller activates the relay

switch, supplying power (+5V) to the CH1786ET. In

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

the CH1786ET when the CH1786ET is in the power

down state.

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. 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.

The pins of the CH1786ET 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 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.

NOTE

A 2400-baud connection rate will only result if both

modems are initially set at 2400 baud.

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.

Zero Power Mode (CH1786ET only).

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

Power Supply. The CH1786 modem module is a

complex set of sub-systems. During the course of

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CH1786 Family of Ultra Small 2400bps Modems

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

Enter: ATS7=255<CR> Disables data-carrier time

Result: OK

out

Enter: ATS10=255<CR> Disables lost-carrier time

Result: OK out

than 500 micro volts peak.

If necessary, use

The following command sequences illustrate

implementation of common Voice/Tone Port

applications.

dedicated power and ground planes. Failure to

provide such operating conditions could cause the

CH1786 to malfunction or to function erratically.

1. To answer a voice call.

(a) Enter: ATH1<CR>

Result:OK

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

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

(c) Begin voice conversation.

input as practical.

It’s recommended a 10 µF

Tantalum capacitor in parallel with a 0.01 µF ceramic

capacitor be used.

2. To switch to data mode.

(a) Drive V.INJ. LOW

(b) At the originate modem:

Enter: ATX1<CR>

Voice/DTMF 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.

Result: OK

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

call.

(a) Enter: ATH<CR>

Result: OK

WARNING: The CH1786 has been FCC Part 68

approved as a data modem only. Utilization of

the Voice/DTMF 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.

4. To place a call to 1234567 using the CH1786’s

DTMF tone generator.

(a) Enter: ATDT1234567;C0<CR>

Result: OK

(b) Drive V.INJ. HIGH

Typically, voice communication would precede data

MODEM CONTROL

communications.

For this case, the following

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

commands should be used to configure the CH1786

(Refer to Figure 4):

pin RXD.

This message indicates command

completion status. Refer to Table 3 for a complete

list of status messages.

INITIALIZING THE MODEM

Before commands may be sent to the CH1786, the

CH1786 must be initialized. Initialization is a two step

activity consisting of:

1. Hard Reset. This is accomplished by applying a

hardware reset pulse to pin RST or by switching

the power off and then back on.

2. Initial modem training. The CH1786 must be

trained to the host ’s speed (2400,1200,300bps)

and parity (odd, even, mark, space or none).

Figure 4. Voice/Tone Injection.

Enter: ATS0=<CR>

Result: OK

Disables auto-answer

These activities are briefly described below.

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CH1786 Family of Ultra Small 2400bps Modems

Reset. Upon applying power to the CH1786, the

CH1786 automatically generates an internal reset

pulse. The user may 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.

<CR> represents carriage return (ASCII 13

or HEX 0D).

When entering commands to the modem, the

backspace character-control-H (ASCII 8 or HEX 08)

may be used to edit mistakes. AT and A/ may not be

edited. 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.

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’s is 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.

Enter: ATE0A<CR>

Result: OK

Modem Training Command Sequence.

The

CH1786 is trained by sending it the following

sequence:

AT Command Set. The available command set is

divided into four types of commands: dial modifiers,

basic

commands,

ampersand

and

percent

Enter: AT<CR>

commands. Refer to the complete list in Table 5.

Result: OK

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

but must be the same case.

<CR> represents carriage return

AT Command Data Rate. With the serial interface,

the rate is speed sensed for parity and format.

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 Terse (abbreviated) or Verbose

(English) status messages.

THE STATUS MESSAGES

The CH1786 responds with a status message after

each command 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.

Result: 0<CR> (Terse)

or

The basic status code subsets are enabled with the

Xn command. Where n=0,1,2,3,4 establishes the

result codes allowed by the user.

Result: <CR><LF>OK<CR><LF> (Verbose)

Where: <CR> represents carriage return (ASCII 13

or HEX 0D).

<LF> represents line feed (ASCII 10 or

HEX 0A).

X0:

X1:

X2:

X3:

X4:

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

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

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

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

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

After responding with an OK, the CH1786 is in idle

mode and is ready to accept additional commands.

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, both the AT and A/ must be in upper case

ASCII. No carriage return is needed for the A/

command.

NOTE

The CH1786 is factory set to X4, which allows all

result codes.

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.

THE COMMAND FORMAT

Typical commands consist of three elements: the

attention sequence, the commands themselves, and

a terminating carriage return.

AT[commands]<CR>.

Where: AT represents attention sequence.

[Commands] represents command strings.

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CH1786 Family of Ultra Small 2400bps Modems

Figure 5. CH1786 Application Diagram

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CH1786 Family of Ultra Small 2400bps Modems

Table 2. CH1786 Pin Descriptions

NAME

TYPE

FUNCTION

1

RING

I/O

RING. Directly connects to the telephone line’s Ring lead through a user supplied

RJ-11C jack.

2

3

4

TIP

RXA

TXA

I/O

O

I

TIP. 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.

5

6

7

8

SPK

NC

O

-

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

No connection.

NC

-

SLEEP

O

SLEEP. 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.

9

NC

-

I

No connection.

10

TXD

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

transmitted when a HIGH is asserted.

11

12

RXD

V/D

O

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

condition is indicated by HIGH.

VOICE/DATA. 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. HIGH indicates the CH1786 is off-

hook and online. Therefore, this pin also reflects the state of the off-hook relay of

the CH1786. See Figure 2.

13

DTR

I

DATA TERMINAL READY. 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.

14

15

16

17

DSR

RI

O

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

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

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.

CTS

DCD

CLEAR-TO SEND. No connect if not using the FAX option. Reserved for flow

control when using FAX option. CTS only active on CH1786 when S24=255.

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

detected. Must be enabled using the &C1 command.

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CH1786 Family of Ultra Small 2400bps Modems

Table 2. CH1786 Pin Descriptions Continuation

NAME

TYPE

FUNCTION

18

HS

O

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

modem is operating at 2400bps.

19

VCC

-

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

peak.

20

21

GND

RST¹

-

I

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

RESET. 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.

22

NC

-

No connection required. For CH179X or CH2056 compatibility, connect to GND or

use as an active LOW input for request to send (RTS) functionality for CH179X/2056

products.

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

(2) Do not drive LED’s directly from any output. Use Buffers.

Table 3. Summary of Result Codes and Meanings.

Result Codes

Status Message

Meaning

0

1

OK

Command Executed

CONNECT

RING

Carrier detected at 300bps

Ring Detected

2

3

NO CARRIER

ERROR

Did not detect carrier

4

Entry error

5

CONNECT 1200

NO DIAL TONE

BUSY

Carrier detected at 1200bps

Off-hook, but no response after 5 seconds

Busy signal detected

6

7

10

CONNECT 2400

Carrier detected at 2400bps

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. The guard time is set by register S12.

The escape character code is set in register S2. At

power-up, the guard time is set to 1 second minimum,

and the escape character is set as “+.” There is no

minimum delay between characters but the maximum

delay is set by register S12.

status message when it is ready to accept

commands. The CH1786 may be put into data mode

by issuing the command ATO<CR>.

AT COMMAND APPLICATIONS

Dialing A Phone Number. The Dial command takes

the form Dn, where n is a string of characters. In the

simplest form, n will be only the digits of the phone

number to be dialed.

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

the escape sequence is received. It will return an OK

Example: Dial number.

Enter:

ATD1234567<CR>

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CH1786 Family of Ultra Small 2400bps Modems

Result:

OK

Enter:

ATDT9,1234567;<CR>

Result: OK

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, permitting communication with the

distant modem.

Automatic Answering. The SO 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.

S0 =

0 DO NOT ANSWER TELEPHONE

1 ANSWER ON RING 1

2 ANSWER ON RING 2

3 ANSWER ON RING 3

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.

255 ANSWER ON RING 255

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

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.

The Serial Interface Lines. The CH1786 supports a

full EIA-232D/V.24 serial interface. Signal levels are

TTL rather than EIA-232D level compatible, which

allows direct connection of the CH1786 to the host

UART without the need for level translation circuitry.

See Table 2 for a complete pin description.

The CH1786 is controlled by sending it serial

commands over TXD and it’s status determined by

monitoring the serial status messages returned on

RXD. DTR is optionally used to reset, terminate calls

or return CH1786 to command mode.

Example: Dial 9,pause, dial number.

Enter:

ATDT9,1234567<CR>

Result: OK

Multiple commas may be used to generate integer

multiples of the specified delay time.

All other serial interface lines may be utilized for the

convenience 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.

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.

Fax Modes. The CH1786 Product Family supports

Send and Receive FAX. The modes and rates are

determined by the AT+F commands. Refer to Table

6A.

Example: Change modem from original-only to

answer mode.

Enter:

ATDT1234567R<CR>

FAX modem processing is explicitly defined in

Result: OK

CCITTV.29,

CCITTV.27,

and

CCITT

V.21

recommendations.

All modulation, wave-form

Multiple commas may be used to generate integer

multiples of the specified delay time.

spectrum, and data processing functions conform to

the appropriate specifications.

Redial Last Number. The repeat command is a

convenient way to execute the previously entered

command line.

Table 4. CH1786 Register Summary.

Register

S0*

S1

Function

Ring to Answer On

Ring Count

Example: Use A/, the repeat command, to redial the

last telephone number dialed.

S2

Escape Code Character

Carriage Return Character

Line Feed Character

Back Space Character

Wait for Dial tone

Enter:

A/

S3

Result: ATDT1234567R<CR> Previous command

OK line executed

S4

S5

S6

Return to Command State. Use ; to return to

command mode offer dialing.

S7

Wait for Data Carrier

Pause Time for Comma

S8

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

return to Command.

2003 Cermetek Microelectronics, Inc.

Page 9

Document No. 607-0004 Revision L1 (06/03)

Cermetek Microelectronics, Inc.

CH1786 Family of Ultra Small 2400bps Modems

Table 4. CH1786 Register Summary

Continuation.

Table 6A.

FAX Command Set Summary.

FAX Command

+FCLASS=n

+F<command>?

+F<command>=?

+FAA=n

Function

Register

S9

Function

Select Service Class

Report Active Configuration

Report Operating Capabilities

Data/Fax Auto Answer

Enhanced Flow Control

Stop Transmission and Wait

Transmit Data

Carrier Detect Response Time

Lost Carrier to Hang-up Delay

DTMF Dialing Speed

S10

S11

S12

Escape Code Guard Time

Bit Mapped Options Register

Modem Test Options

+FF

S14*

S16

+FTS=n

+FTSM=n

+FTH=n

S21*

S22*

S23*

S24

Bit Mapped Options Register

Sleep Mode Inactivity Time

Delay to DTR

Receive Data

+FTH=n

Transmit Data with HDLC

Framing

+FRH=n

Receive Data with HDLC

Framing

S25*

S27*

S28*

+FRT=n

Receive Test Data

Transmit test Data

Bit Mapped Options Register

+FTTn=m

Table 6B.

Dial Modifiers Summary.

Function

Note

Dial Modifiers

In Tables 4, 5, 6A-6C an * signifies parameters that

are stored in NVRAM upon receipt of the &W

P

R

Pulse Dial

Originate Call in Answer

Mode

command.

The CH1786LC, CH1786LCNE,

CH1786NE and CH1786NH do not contain NVRAM

and, therefore, do not support data storage after

power down. 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 website at www.cermetek.com.

T

Touch Tone Dial

Wait for Dial Tone

Return to Idle State

Wait for Quiet Answer

Command

W

;

@

!

Flash Hook

,

Paul

0-9

Dial Digits/Characters

Table 5. CH1786 AT Command Set Summary.

A,B,C,D

Basic

Commands

AT

Function

Table 6C. Ampersand and Percent Commands.

Attention Code

Ampersand

Commands

&Cn*

Function

A

Answer command

A/

Repeat last Command

Communications Standard Option

Dial Command

Data Carrier Detect Option

Data Terminal Ready Option

Load Factory Defaults

Guard Tone Option

BN*

D

&Dn*

&F

E*

Off-Line Character Echo Option

Switch Hook Control Option

Speaker Volume Option

Speaker Control Option

On-Line Command

&Gn*

Hn

&Pn*

Make to Break Ratio Section

Data Set Ready Option

Test Command Option

View Active Configuration

Store Active Profile

Ln*

Mn*

On

&Sn*

&Tn

&V

P

Pulse Dial

&Wn*

&Yn*

Qn*

Sn

Result Code Display Option

Select an S Register

Write to an S Register

Read an S Register

Recall Active Profile

&Zn*

Store Telephone Numbers

Function

Sn=

Sn?

Vn*

Xn*

Percent

Commands

%Dn

Result code Form Option

Result Code Set/Call Progress

Option

DTMF Attenuation

Load Secondary Factory

Defaults

%J

+++

,

Escape Code Sequence Pause

Pause

PHONE LINE CONNECTION GUIDELINES

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.

?

Returns Last addressed S Register

Long Space Disconnect Option

On Line Echo character Option

Reset

Yn*

Fn

Z

2003 Cermetek Microelectronics, Inc.

Page 10

Document No. 607-0004 Revision L1 (06/03)

Cermetek Microelectronics, Inc.

CH1786 Family of Ultra Small 2400bps Modems

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).

CH1786 HANDLING AND ASSEMBLY

RECOMMENDATIONS

The CH1786 contains static-sensitive components

and should only be handled by personnel and in

areas that are properly protected against static

discharge.

The two recommended mounting

3. Connection to phone line should be made

through an RJ-11C jack.

techniques for physically connecting the CH1786 to a

PCB are discussed below.

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.

Direct Soldering.

The CH1786 may be wave

soldered. All CH1786 products are hermetically

sealed (except the CH1786LCNE, CH1786NE, and

CH1786NH) and will not be harmed by industry

standard wave soldering processes.

Cermetek

recommends against exposing the non-hermetic

CH1786LCNE, CH1786NE, and CH1786NH to

aqueous based rinsing processes.

5. The RING and TIP PCB traces should be as

short as possible and oriented to prevent

coupling other high speed or high frequency

signals present on the host circuit PCB.

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 during shipping. Cermetek recommends using

sockets from Samtec. See Application Note # 130,

Summary of Recommended Suppliers.

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, CH1786LCNE, and CH1786NH

(only) requires external surge protection (see

Figure 7B). This is mandatory to maintain FCC

Part 68 conveyed approval.

FCC REGISTRATION

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.

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.

9. The supplied FCC registration label must be

applied visibly on the outside of the product.

In addition to restriction notification, the FCC requires

that Cermetek make all repairs to all products in the

10. The product’s User Manual must provide the user

with instructions for connection and use as

recommended in the FCC Registration Section

below.

CH1786 family.

If repairs are necessary after

installation of the CH1786 in the end product and the

end product has been delivered to the end 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.

FOR YOUR USER’S MANUAL

The FCC Part 68 rules require the following (or

equivalent) be provided to the end user of equipment

containing a DAA.

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

Figure 6. Speaker Control Circuit: Optional to

allow for call progress monitoring.

2003 Cermetek Microelectronics, Inc.

Page 11

Document No. 607-0004 Revision L1 (06/03)

Cermetek Microelectronics, Inc.

CH1786 Family of Ultra Small 2400bps Modems

prohibited. Connection to party lines service is

subject to state tariffs.

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).

Changes in Attestation Procedure for Plugs and

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

DEFAULT STATUS, PERFORMANCE, AND

SPECIFICATIONS

The following is a summary of the Default

Configuration Profile installed by Cermetek

Microelectronics, Incorporated, prior to delivery

of the CH1786.

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.

Async mode selected

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

2400bps

Bell 212A operation at 1200bps

Even parity

Auto answer enabled (Disabled on CH1786NH)

Command echo ON

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 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

In certain circumstances, it may be necessary for the

telephone company to request information from you

concerning the equipment which you have connected

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

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.

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

If Problems Arise.

If any of your telephone

Back space character =08

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.

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

When you are notified, you will be given the

opportunity to correct the problem and informed of

your right to file a complaint with the FCC. Contact

your local telephone service provider if you have nay

questions about your phone line.

Sleep mode inactivity time =5 seconds

Long space disconnect disabled

2003 Cermetek Microelectronics, Inc.

Page 12

Document No. 607-0004 Revision L1 (06/03)

Cermetek Microelectronics, Inc.

CH1786 Family of Ultra Small 2400bps Modems

Figure 7.

PSTN Line Interface for all CH1786 Products.

1. Currently Limiting PSTN Protection Line

Device.

B. For CH1786NH, the required surge protection

(identified as D1 in dashed Box 2) must be

Currently limiting devices are mandatory to meet

UL safety standards. To maintain conveyed FCC

Part 68 approval, the current limiting components

identified as F1 and F2 in dashed Box #1 must

also survive FCC Part 68 surge testing. Refer to

Cermetek Application Note #126, Supplemental

PSTN Line Protection, for more details. Refer to

Application Note # 130, Summary of Recommend

Suppliers, for a list of suppliers and associated

part numbers.

supplied externally.

The purchaser must

include some form of surge protection as

described herein to maintain conveyed FCC

Part 68 approval.

C. In most environments, 2 terminal surge

suppressors are adequate.

For severe

environments, use an external 3 terminal

device with an earth ground.

3. EMI/RFI Suppression.

A. A Polyfuse (rated at 0.15 amps) is preferred

because it resets automatically upon removal

of the current flow. Non-resettable devices

are also acceptable. Refer to Application Note

#130 for a complete list of recommended

vendors and associated part numbers.

B. Resistors (10Ω carbon film or 1/8 watt

minimum) may be used in Canada, as Canada

has no requirements that PSTN equipment be

operational after a Type B surge test.

C. Although CSA CS-03 Part 1 (Canada) follows

the requirements of FCC Part 68 (USA),

Cermetek recommends contacting DOT

(Canada) and/or a certified independent lab to

verify compliance. For Canada, use either

10Ω resistors (carbon film or SMD parts 1/8

watt minimum) as described in paragraph B

above.

No external EMI/RFI noise suppression circuitry is

required to maintain conveyed FCC Part 68

approval. However, additional suppression, if

required for other reasons, may be added as

described below in Sections 3A-3B without

adversely affecting FCC Part 68 approval.

A. To provide adequate EMI/RFI suppression,

the capacitor/inductor network contained in

dashed Box #3 should be located as close to

the RJ11 Jack as possible. Further, this

network should be provided with an excellent

ground path to the chassis.

B. Capacitors C1 and C2 should not exceed

0.005µf. They must have a rating of 1.5KV

and typically are 0.001µf ± 20%. Inductors L1

and L2 may be either individual inductors or a

dual inductor. Refer to Application Note #130

for a complete list of recommended vendors

and associated part numbers.

For UL

2. Over Voltage and Lightning Protection.

applications, choose capacitors and inductors

that are UL 1950 listed. The actual values of

the components used may vary depending on

the end product design.

A. Surge Protection is provided by internal

circuitry contained within all CH1786 Products

except the CH1786NH (see Figure 7). No

additional external components are required to

maintain conveyed FCC Part 68 approval for

all

CH1786

Products

(excluding

the

CH1786NH).

2003 Cermetek Microelectronics, Inc.

Page 13

Document No. 607-0004 Revision L1 (06/03)

Cermetek Microelectronics, Inc.

CH1786 Family of Ultra Small 2400bps Modems

Table 7. CH1786 System Data Mode Compatibility Specifications.

Parameter

Asynchronous

Specification

2400, 1200 600 bps character

asynchronous.

Parameter

Receive Carrier

Frequencies

V.22 bis, V.22,

212A

Specification

Originate 2400Hz ± 7Hz

Answer 1200Hz ± 7Hz

0-300 bps asynchronous

Asynchronous

Range

Speed

TXD may differ +1%, -2.5%

from modem output. Offsets

will be corrected by adding/

deleting stop bits.

Bell 103

Answer

‘space’ 2020Hz ±

7Hz

Answer ‘mark’ 2225Hz ±

7Hz

Originate ’space’ 1070Hz ±

7Hz

Originate ‘mark’

7Hz

1270Hz ±

Asynchronous Format

Telephone Line Interface

Modulation

8,9,10 bits, including start,

stop, parity.

Receiver

OFF to ON threshold –43

dBm

Sensitivity

ON to OFF threshold –48

dBm

Two-wire full duplex over

public switched network. On-

chip hybrid and billing delay

timers.

Billing Delay

Hysteresis

2.0 to 3.0 seconds (T_a=25°C)

V.22 bis, 16 point QAM at 600

baud. V.22 and 212A, 4 point

2 dB minimum

DPSK at 600 baud.

103

Binary phase coherent FSK.

Alternate ‘ones’ and ‘zeros’

and error detector, to be used

along with most loopbacks. A

number indicating the bit

errors detected is sent to DTE.

Originate 1200Hz ± .01%

Self

Test

Pattern

Line

Fixed

compromise

transmit.

Generator

Equalization

equalization,

Adaptive

equalizer

for

PSK/QAM, receive.

Transmit

Carrier

Diagnostic

Available

Local analog loopback.

Remote digital loopback.

Frequencies V.22 bis,

V.22, 212A

Answer 2400Hz ± .01%

Request

remote

digital

loopback.

Local

interface

loopback

modem with self-test.

Bell 103

Originate ’space’ 1070Hz ±

.01%

Call Progress

With speaker or quiet screen

messages (No dial tone,

busy, ring-back, modem

answer tone and voice).

IBX PC/XT/AT bus

Tones Detected

Originate ‘mark’

.01%

1270Hz ±

Answer

.01%

‘space’ 2020Hz ±

Computer

Interface

compatible with an

Answer

.01%

‘mark’

2225Hz ±

8250/16450/16550A UART

as a serial controller.

2003 Cermetek Microelectronics, Inc.

Page 14

Document No. 607-0004 Revision L1 (06/03)

Cermetek Microelectronics, Inc.

CH1786 Family of Ultra Small 2400bps Modems

Table 8. CH1786 Electrical Specifications.

Description

Parameter

Min.

Typ.

5.0

50

Ma

x.

Units

V

V_CC

I_CCOff Hook

I_CCOn Hook

I_CCPD

Positive Supply Voltage- Noise less than 50mV

Nominal Operating Current when modem is OFF Hook

Nominal Operating Current when modem is ON Hook

Power Down Current

4.75

5.2

5

75

mA

V

25

50

10

V_IH

High Level Input Voltage*

2

V_IL

Low Level Input Voltage*

-0.3

15

0.8

V

I_IN

Input Leakage Current (TXD, DTR, RTS)

10

0

uA

I_LO

C_P

Leakage Current DCD, HS, RXD, SLEEP, DSR

Capacitive Lead (TXT, DTR, RST)

10

uA

pF

VT+

VT-

V_OH

V_OL

Positive Hysteresis Threshold for RESET pin

Negative Hysteresis Threshold for RESET pin

High Level (I_OH= 0.5mA)*

2.5

1.8

V

2.4

Low Level (I_OL= 1.6mA)*

0.6

Test conditions: VCC = 5V ± 10%, Temp = 0°C to 70°F (unless otherwise stated).

*Output Load = 50 pF ± one TTL.

Table 9. CH1786 Electrical Specifications.

Parameter

Minimum

Typical

Maximum

Units

Comments

Off Hook Impedance

20

Ohms

Trans Hybrid Loss

Ring Voltage Loop

25

dB

V_pp

600 Ohm, RXA, TXA

110V

-0.5

250V

100

On 48VDC line voltage for

sustained periods

Line Loop Current-(Off-

Hook)

20

15

mA

Return Loss @ 1000Hz

dB

600 Ohm

Ring Frequencies

40

Hz

Receiver Insertion Gain

Transmit Power

0.0

-9.5

1.0

50

+0.5

5

dBm

dB

600 Ohm- Data Mode

Delay

First Character After Reset

Inter Character Delay

Command Delay

0.5

20

sec

msec

Between all command

characters

100

10

200

Between all AT commands

Minimum Reset Pulse

Duration

If user supplied

2003 Cermetek Microelectronics, Inc.

Page 15

Document No. 607-0004 Revision L1 (06/03)

Cermetek Microelectronics, Inc.

CH1786 Family of Ultra Small 2400bps Modems

Table 10. Other Performance Specifications.

Parameter

Minimum

Typical

Maximum

Units

dB

ms

pps

%

Comments

Tone 2^ndHarmonic

Distortion

-35

HYB enabled into 600Ω

DTMF Twist (Balance)

3

DTMF Tone Duration

Pulse Dialing Rate

50

8

255

20

95ms default

10

10pps default

Pulse Dialing Make/

Break

39/61

33/67

US, Canada default

UK, Hong Kong

789ms default

Pulse Dialing Make/

Break

%

Pulse Interdigit Interval

700

3000

ms

Hz

dB

Hz

dB

Hz

sec

dB

Guard Tone Frequency

Guard Tone Amplitude

Guard Tone Frequency

Guard Tone Amplitude

550

-6

Referenced to High Channel

Transmit

Referenced to High Channel

Transmit

1800

-9

Referenced to High Channel

Transmit

Referenced to High Channel

Transmit

High Channel Transmit

Amplitude

-1

Referenced to Low channel,

Guard tone enabled

Guard Tone 2^nd

-40

Harmonic Distortion

Call Progress

120

2

620

255

Passband Frequency

Wait Time for Dial tone

Two second default

Return loss @ 1000Hz

30

T_r=600Ω + 2.16 µF

Table 11. Analog Characteristics.

Name

Type

Characteristic

Value

SPK

O(DF)

Minimum Load

300Ω

Maximum Capacitive Load

Output Impedance

Output voltage

0.01µ

10Ω

2.5± 1.6V

<20mV

D.C. Offset

2003 Cermetek Microelectronics, Inc.

Page 16

Document No. 607-0004 Revision L1 (06/03)

Cermetek Microelectronics, Inc.

CH1786 Family of Ultra Small 2400bps Modems

Table 12. CH1786 Pin Functions.

PACKAGE CONNECTION TABLE

PIN NO.

FUNCTION

RING

TIP

PIN NO.

FUNCTION

V/D

1

2

12

13

14

15

16

17

18

19

20

21

22

DTR

DSR

RI

3

RXA

TXA

4

5

SPK

CTS

DCD

HS

6

NC

7

NC

8

SLEEP

NC

VCC

GND

RST

NC

9

10

11

TXD

RXD

Figure 8.

CH1786 Physical Dimensions.

2003 Cermetek Microelectronics, Inc.

Page 17

Document No. 607-0004 Revision L1 (06/03)

Cermetek Microelectronics, Inc.

CH1786 Family of Ultra Small 2400bps Modems

Table 13. Summary CH1786 Family of Products.

Summary of Features

Model

Operating

Temperature

CH1786

Full function, Voice/Inject, NVRAM, FCC Part 68 approved, UL 1950

Listed, Hermetic

0°C to 70°C

CH1786ET

CH1786FX

CH1786FXNE

CH1786LC

CH1786LCNE

CH1786NE

CH1786NH

Full function, Voice/Inject, NVRAM, Zero Power Option, FCC Part 68

Approved, UL 1950 Listed, Hermetic

-40°C to 85°C

0°C to 70°C

Full function, FAX, Voice/Inject, NVRAM, FCC Part 68 approved, UL

1950 Listed, Hermetic

Full function, FAX, Voice/Inject, NVRAM, FCC Part 68 approved, UL

1950 Listed, Non-Hermetic

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

Hermetic

Full function, Voice/Inject, FCC Part 68 approved, UL 1950 Listed,

Non-Hermetic

Full function, Voice/Inject, NVRAM, FCC Part 68 approved, UL 1950

Listed, Non-Hermetic

Full function, FCC Part 68 Approved, Non-Hermetic, Listed UL 1950

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.

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/

2003 Cermetek Microelectronics, Inc.

Page 18

Document No. 607-0004 Revision L1 (06/03)


型号：	CH1786
厂家：	ETC
描述：	CH1786 Family of Ultra Small 2400bps Modems CH1786系列超小型的是2400bps调制解调器调制解调器
文件：	总18页 (文件大小：544K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

CH1786 [ETC]

相关型号：

CH1786ET

CH1786FX

CH1786LC

CH1786NH

CH1787

CH1787ET

CH1789ND

CH1790

CH1792

CH1793

CH1793ET

CH1793LT