XE2420-ITR Просмотр технического описания (PDF) - Xecom

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XE2420-ITR

2400 BPS Surface-Mountable Integrated Sealed-Hybrid Modem

Xecom 

Application Note: XE2420 Shared Line Feature

For applications where the XE2420 shares a telephone line with a telephone handset, Xecom has provided four

hardware hooks for connecting two monitoring circuits. These circuits monitor the status of the telephone line to

prevent the modem from interfering with a voice call.

The Connect Detection Circuit monitors the telephone loop voltage when the modem is not in use. This allows the

system host to check the status of the telephone line before initiating a call. The ConDetect signal will be be high

when the phone line is available but goes low to indicate that the telephone line is in use.

The Handset Interupt or 911 Interrupt circuit monitors loop current while the modem is in the off-hook state. This

circuit detects the change in loop current which occurs when a handset on the shared telephone line is lifted. The

HSInterrupt output will go low momentarily if the handset is lifted during data communications. The system host can

then immediately abort the modem connection and permit the user to complete their call.

Parts List for Shared Line Feature Application Note

Reference

Designation Qty Description

Reference

Designation Qty Description

C1, C2

2 Cap. 470 pfd 2600V

R7

1 Resistor, 56K 5%

C3

1 Cap. 10 ufd 20% 16V

R8

1 Resistor, 33K 5%

C4

1 Cap. 1 Ufd, 20% 10V

R9

1 Resistor, 402K 5%

F1, F2

2 PTC, TR600-150

R10

1 Resistor, 1M 5%

FB1, FB2

2 Ferrite, ACB2012L-120

R11

1 Resistor, 1.5K 5%

Q1

1 Trans. FMMT3904

R12

1 Resistor, 20K 5%

R1, R2

2 Resistor, 10M 5%

R13

1 Resistor, 100K 5%

R3, R5, R6

3 Resistor, 200K 1%

U1, U2

2 OP Amp, TLC271CD

R4

1 Resistor, 280K 1%

U3

1 Opto-coupler, PS2705-1

XECOM

(10)

XE2420

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