Cermetek Microelectronics, Inc.
High Speed Modem and FAX Family
2003 Cermetek Microelectronics, Inc.
Page 8
Document No. 607-0003 Revision K3 (09/03)
Table 3.
HS Modem Family Pin Descriptions.
PIN
NAME
I/O
FUNCTION
1
RING
I/O
TELCO/TELSET INPUT. Directly connects to the telephone line’s RING lead through a
user supplied RJ-11C jack.
2
TIP
I/O
TELCO/TELSET INPUT. Directly connects to the telephone line’s TIP lead through a user
supplied RJ-11C jack.
3
T1
I/O
ANALOG VOICE INJECTED. Input (See Figure 5). 2.2V P-P max. Let float if not used.
4
NC
-
No connection.
5
SPK
O
SPEAKER. Audio output for speaker. See speaker control diagram.
6
NC
-
No connection.
7
NC
-
No connection.
8
NC
-
No connection.
9
NC
-
No connection.
10
TXD
I
TRANSMIT DATA. Serial Transmit data input. Marking, or a binary 1 condition, is
transmitted when a HIGH is asserted.
11
RXD
O
RECEIVE DATA. Serial Receive data output. Received marking or a binary 1 condition is
indicated by a HIGH.
12
NC
-
No connection.
13
DTR
I
DATA TERMINAL READY. Active LOW. Switching off DTR can either return modem to
command state, disconnect phone call, or reset the modem. DTR should be set LOW
when not used.
14
DSR
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.
15
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.
16
CTS
O
CLEAR TO SEND. Active LOW. Indicates that the modem is ready to accept data from
the DTE.
17
DCD
O
DATA CARRIER DETECT. LOW indicates a data carrier from a remote modem has been
detected. This feature must be enabled using the &C1 command.
18
NC
-
No connection.
19
VCC
-
POWER SUPPLY. 5 Volts ± 5%. Note: Noise should be less than 25mV peak-to-peak.
20
GRD
-
GROUND. Note: Noise should be less than 25mV peak-to-peak.
21
RST
I
RESET. Active HIGH. This input must be asserted HIGH for at least 10-msec to reset the
modem. RESET is then returned to LOW for normal operation. If no system reset is
available, let this pin float to enable the internal reset.
22
RTS
I
REQUEST TO SEND. Active LOW. Used for flow control. Should be tied low if not used.
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.
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