CH1788ET 데이터 시트보기 (PDF) - Cermetek Microelectronics

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CH1788ET

Surface Mount PLCC 2400bps Modem

Cermetek Microelectronics 

Cermetek Microelectronics, Inc.

CH1788 Surface Mount PLCC 2400bps Modem

CH1788

Used for LIU/911/General IO

Used for LIU/911/Audio Control

DTE Signal

DTE Signal

DTE Signal

DTE Signal

DTE Signal

DTE Signal

Used for LIU/911/Detection

DTE Signal

Optional High Reset Input

1

2

A1

3

OH

RTS

4

5

6

7

RI

CTS

DSR

DCD

8

9

DTR

A2

10 TXD

11 RST

Top View

RXD

22

21

GND

VCC

S2

20

19

S1 18

V-

V+

TIP

15

14

13

RING 12

DTE Signal

Power Input +5V

Optional S1/S2 Audio

Monitor/Tone/Voice

V+/V- Optional

CID Input

Telephone Line

Input

High Voltage Section

Figure 2. CH1788 Pin Configuration. See Table 2 for detailed Pin Descriptions.

PIN NAME TYPE

Table 2. CH1788 Pin Descriptions.

FUNCTION

1

A1

O

Optional Input. Active high. Used when implementing the 911 Priority Pick-Up

circuit or the Line In Use circuit.

2

OH

O

Off-Hook. Active low. OH Indicates when the CH1788 is Off-Hook. Used in Line

In Use, 911 Priority Pick-Up applications and for Audio Control.

3

RTS

I

Request To Send. Active low. Used for optional flow control. Used in conjunction

with the Clear to Send (CTS) pin as a handshaking signal. See the details of

register S90.

4

RI

O

Ring Indication. Active low. For each occurrence of a valid ring signal, this pin will

pulse low for 70 ms. This output signal follows the frequency of the ringing signal

and is typically in the 20 to 40 Hz range with a cadence of 2 seconds on with 4

seconds off.

5

CTS

O

Clear to send. Active low. Used for optional flow control. Used in conjunction with

the Request To Send (RTS) pin as a handshaking signal. See the details of

register S90.

6

DSR

O

Data Set Ready. Active low. A low indicates that handshaking with the remote

modem is in progress and/or the carrier of the remote modem has been detected

and a valid connection is imminent as measured by DCD being active. This feature

is enabled with the N command.

7

DCD

O

Data Carrier Detect. Active low. This output must be enabled with the C

command. When enabled, it will become active when both the originated and

answering modems are connected and a data carrier has been detected.

NOTE: 1. All unused pins should be left unconnected when not required in a specific application,

unless specifically directed otherwise.

2. See DC characteristics before attempting to drive an LED directly from the output of any pin.

2003 Cermetek Microelectronics, Inc.

Page 5

Document No. 607-0018 Revision A2 (07/03)

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