CH1786LC Cermetek Microelectronics, CH1786LC Datasheet - Page 7

• Manufacturer Part Number: CH1786LC
• Manufacturer: Cermetek Microelectronics

Specifications of CH1786LC

• Main Category: Single Chip
• Data Rate: 2.34375Kbps
• Power Supply Type: Analog
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (min): 4.75V
• Operating Supply Voltage (max): 5.25V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Through Hole
• Lead Free Status / RoHS Status: Supplier Unconfirmed

Cermetek Microelectronics, Inc.
2004 Cermetek Microelectronics, Inc.
PIN
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
SLEEP
NAME
RING
RXA
SPK
TXD
RXD
DTR
DSR
CTS
TXA
V/D
TIP
NC
NC
NC
RI
TYPE
I/O
I/O
O
O
O
O
O
O
O
O
I
-
-
-
I
I
No connection.
No connection.
No connection.
RING. Directly connects to the telephone line’s Ring lead through a user supplied
RJ-11C jack.
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.
SPEAKER. Audio output for speaker. See speaker control schematic in Figure 6.
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.
TRANSMIT DATA. Serial Transmit data input. Marking or a binary 1 condition is
transmitted when a HIGH is asserted.
RECEIVE DATA.
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.
DATA TERMINAL READY. Active LOW. Switching off DTR can either return
modem to command state, disconnect phone call, or reset modem. DTR should be
set LOW when not used.
DATA SET READY.
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.
CLEAR-TO SEND. Ground if not using the FAX option. Reserved for flow control
when using FAX option. CTS only active on CH1786 when S24=255.
Table 2. CH1786 Pin Descriptions
Serial Receive data output.
Page 7
LOW indicates handshaking with a remote modem is in
FUNCTION
CH1786 Family of Ultra Small 2400bps Modems
Document No. 607-0004 Revision L4 (08/04)
Received marking or binary 1