CH2100 데이터 시트보기 (PDF) - Cermetek Microelectronics
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CH2100 Datasheet PDF : 10 Pages
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With the exception of the U.S., most countries (including Canada)
require submission of the final product or system containing the
CH2100 to the appropriate governing regulatory agency for
approval. Typically this is accomplished by submitting the final
end product to an independant test house or consultant for
evaluation. The test house/consultant then forwards the test
results and applicable documents to the regulatory agency. Call
Cermetek for a list of consultants.
SUPPORTED FEATURES
“AT” Command Set.
A 40-character command line is supported. The command line
starts with AT and may contain standard or enhanced commands.
A summary is available in this data sheet while a detailed descrip-
tion is available from our web site.
Serial Host Interface.
The serial interface signals conform to V.24 (EIA-232).
See pin description.
Transmission Speed.
In normal operation, the originating modem initiates the call and
attempts to connect to the answering modem at a speed estab-
lished 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 originat-
ing 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 termi-
nate the call. Table 1 indicates the connection rate that will result
when the calling modem’s Inital Trained Rate and the answering
modem’s Initial Trained Rate are different.
Note that a 2400 baud connection rate will only result if both mo-
dems are initially set at 2400 baud.
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 train-
ing also sets the speed of the data for originate calls. The CH2100
will automatically adjust to the originators speed when answering
calls.
The CH2100 matches the host’s parity when it returns status mes-
sages to the host. During a data connection, however, the modem
passes parity through without interpretation or alteration.
Power Supply.
The CH2100 modem module is a complex set of sub-systems.
During the course of normal operation the CH2100 decodes ana-
log 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 dedi-
cated power and ground planes. Failure to provide such operating
conditions could cause the CH2100 to malfunction or to function
erratically.
The CH2100 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 is recommended that a
10 µF or greater Tantalum capacitor in parallel with a 0.01µF ce-
ramic capacitor be used.
MODEM CONTROL
The CH2100 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 completion status. Re-
fer to Table 3 for a complete list of result codes.
Reset on Power Up.
The user can also reset the modem externally by applying a low-
going reset pulse to the RST pin for at least 10ms after the +5V
power supply has stabilized. This can be accomplished in one of
two methods. In the Reset on Power Up method, a resistor/ca-
pacitor network is used. Refering to figure 2, the reset pulse, with
the appropriate delays, are generated automatically when 5V are
applied simultaneously to the CH2100 and to the Reset on Power
Up circuit. Delay sending commands to CH2100 for 200ms after
reset has been initiated to allow the CH2100 to properly reconfigure.
TTL Controller Reset.
To reset the modem externally using the second reset method,
TTL Controller Reset, the modem must be powered up and the
5V supply must have stabalized prior to utilizing this method.
Refering to the TTL Controller Reset circuit in figure 2, a 10msec
low-going pulse is sent from the controller through the inverter.
Delay sending commands to CH2100 for 200ms after reset has
been initiated to allow the CH2100 to properly reconfigure.
Sleep Mode.
To minimize power consumption, the CH2100 includes a power
down feature called Sleep Mode. When activated, the CH2100 will
automatically enter Sleep Mode after 0 to 254 seconds of inactivity.
The inactivity delay is selected using the ATS24 command. The
CH2100 is delivered from the factory with a 5 second inactivity
delay enabled (i.e., ATS24=5). The CH2100 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. In Sleep Mode,
power is reduced to approximately 50% of normal operating power.
Table 1. Connection Rates
Answering Modem Initial Connection Rate Resulting When
Trained Rate
Calling Modem Initial Trained Rate is:
300
1200
2400
300
300
1200
1200
1200
300
1200
1200
Ring Indicator (RI).
The RI pin toggles low when the CH2100 detects an incoming call.
The RI pin is TTL compliant and can be utilized to activate external
circuitry including the external RST pin.
2400
300
1200
2400
1999 Cermetek Microelectronics, Inc.
Document No. 607-2100 Rev. C (8/99) 2
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