CH1786FX 데이터 시트보기 (PDF) - Cermetek Microelectronics

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CH1786FX

CH1786 Family of Ultra Small 2400bps Modems

Cermetek Microelectronics 

Cermetek Microelectronics, Inc.

PIN NAME TYPE

1

RING

I/O

CH1786 Family of Ultra Small 2400bps Modems

Table 2. CH1786 Pin Descriptions

FUNCTION

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

RJ-11C jack.

2

TIP

I/O TIP. Directly connects to the telephone line’s Tip lead through a user supplied RJ-

11C jack.

3

RXA

O

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

CH1786NH.

4

TXA

I

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

CH1786NH.

5

SPK

O

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

6

NC

-

No connection.

7

NC

-

No connection.

8

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

-

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 binary 1

condition is indicated by HIGH.

12

V/D

O

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

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. No connect if not using the FAX option. Reserved for flow

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

17

DCD

O

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

detected. Must be enabled using the &C1 command.

2003 Cermetek Microelectronics, Inc.

Page 7

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

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