CH1782A Просмотр технического описания (PDF) - Cermetek Microelectronics

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производитель

CH1782A

Family of Ultra Small Modem Modules V.22bis-2400bps

Cermetek Microelectronics 

Cermetek Microelectronics, Inc.

CH1782A Family of Ultra Small Modem Modules V.22bis-2400bps

PIN NAME I/O

Table 3. CH1782A Pin Description Continuation.

FUNCTION

9 TIP I/O TIP. Directly connects to the telephone line’s Tip lead through a user supplied RJ-11C jack.

10 RING I/O RING. Directly connects to the telephone line’s Ring lead through a user supplied RJ-11C

jack.

11 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.

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 CH1782A is off-hook

and online. Therefore, this pin also reflects the state of the off-hook relay of the CH1782A.

See Figure 2.

13 CTS

14 RST(1)

O CLEAR TO SEND. Output always LOW. Reserved for flow control when using FAX option.

CTS only active on CH1782A when S24=255.

I RESET. Active HIGH. This input must be asserted HIGH for at least 10 ms to reset the

modem. RESET is then returned LOW for normal operation. If no system reset is available,

let this pin float to enable internal reset.

15 HS

O SPEED INDICATION. HIGH speed select output. A low on this pin indicates the modem is

operating at 2400bps.

16 TXD

I TRANSMIT DATA. Serial Transmit data input. Marking or a binary 1 condition is transmitted

when a HIGH is asserted.

17

-

NC NO CONNECTION.

18

-

NC NO CONNECTION.

19

-

NC NO CONNECTION.

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

21

-

NC NO CONNECTION.

NOTE

If the VCC power supply has a slow power up ramp time, the internal reset may be ineffective. In this case, use

an external reset to cycle the VCC to perform the reset function.

2002 Cermetek Microelectronics, Inc.

Page 7

Document No. 607-0009 Revision C (01/03)

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