T7234A Просмотр технического описания (PDF) - Agere -> LSI Corporation

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T7234A

Compliance with the New ETSI PSD Requirement

Agere -> LSI Corporation 

T7234, T7237, and T7256

Data Sheet Advisory

Advisory

July 1998

Application Circuit

Please change the value of capacitor C15 from 0.1 µF to 1.0 µF in Figure 11 of the T7234 data sheet, Figure 17 of

the T7237 data sheet, and Figure 20 of the T7256 data sheet. The following schematic shows the correct value

(1.0 µF) for C15.

MLT CIRCUIT

+5 V

R8

17.8 kΩ

R10

10 kΩ

8

6

SCNT1

OPTOIN

PIN

5

R9 7

2.2 MΩ

U2

2

3

HCPL-0701

CA

1.0 µF

C15

1.0 µF

R11

137 Ω

R12

137 Ω

ZD

(PLACE THIS CAPACITOR AS

CLOSE AS POSSIBLE TO THE LH1465)

LH1465AB

8 TC

PR+ 1

7 RS

6 PD

U3

T2

R3

5 COM

PR– 4

R14

1.1 kΩ

2W

R15

1.1 kΩ

2W

FOR NORTH AMERICAN

APPLICATIONS ONLY

RING

TIP

Figure 1. MLT Circuit Showing New Placement of Zener Diode (ZD) and Capacitor (CA)

5-7034(C)

In the ILOSS mode (refer to ANSI T1.601 1992, Section 6.5.2), the NT generates a scrambled, framed, 2B1Q sig-

nal such as SN1 and SN2. When the ILOSS mode is applied to circuits with the LH1465, it was observed that for

some short loop lengths, the NT, once in the ILOSS mode, would not respond to further maintenance pulses until

the ILOSS timer expired. It was discovered that there is some portion of the transmitted 2B1Q signal from the NT

that passes through the LH1465 to the optoisolator. This causes the optoisolator to report incorrect dial pulses at

its output, and thus prevent the NT from properly exiting the ILOSS mode.

To correct this situation, the dropout voltage (voltage at the Tip/Ring needed to turn on the optoisolator) of the

optoisolator driver on the LH1465 is raised using the 3.6 V zener diode ZD (for example, Motorola* MMSZ4685T1).

Capacitor CA is a 1.0 µF ±10% tantalum chip capacitor, with a voltage rating of at least 16 V. CA is added to provide

a level of filtering for the transition points (turn-on or turn-off) of the optoisolator input voltage, which increases the

robustness of the circuit.

* Motorola is a registered trademark of Motorola Inc.

For additional information, contact your Microelectronics Group Account Manager or the following:

INTERNET: http://www.lucent.com/micro

E-MAIL:

docmaster@micro.lucent.com

N. AMERICA: Microelectronics Group, Lucent Technologies Inc., 555 Union Boulevard, Room 30L-15P-BA, Allentown, PA 18103

1-800-372-2447, FAX 610-712-4106 (In CANADA: 1-800-553-2448, FAX 610-712-4106)

ASIA PACIFIC: Microelectronics Group, Lucent Technologies Singapore Pte. Ltd., 77 Science Park Drive, #03-18 Cintech III, Singapore 118256

Tel. (65) 778 8833, FAX (65) 777 7495

CHINA:

Microelectronics Group, Lucent Technologies (China) Co., Ltd., A-F2, 23/F, Zao Fong Universe Building, 1800 Zhong Shan Xi Road,

Shanghai 200233 P. R. China Tel. (86) 21 6440 0468, ext. 316, FAX (86) 21 6440 0652

JAPAN:

Microelectronics Group, Lucent Technologies Japan Ltd., 7-18, Higashi-Gotanda 2-chome, Shinagawa-ku, Tokyo 141, Japan

Tel. (81) 3 5421 1600, FAX (81) 3 5421 1700

EUROPE:

Data Requests: MICROELECTRONICS GROUP DATALINE: Tel. (44) 1189 324 299, FAX (44) 1189 328 148

Technical Inquiries: GERMANY: (49) 89 95086 0 (Munich), UNITED KINGDOM: (44) 1344 865 900 (Bracknell),

FRANCE: (33) 1 48 83 68 00 (Paris), SWEDEN: (46) 8 600 7070 (Stockholm), FINLAND: (358) 9 4354 2800 (Helsinki),

ITALY: (39) 2 6601 1800 (Milan), SPAIN: (34) 1 807 1441 (Madrid)

Lucent Technologies Inc. reserves the right to make changes to the product(s) or information contained herein without notice. No liability is assumed as a result of their use or application. No

rights under any patent accompany the sale of any such product(s) or information.

Copyright © 1998 Lucent Technologies Inc.

All Rights Reserved

Printed in U.S.A.

July 1998

AY98-025ISDN (Replaces AY98-020ISDN)

(Must accompany DS97-410ISDN, DS97-411ISDN, and DS97-412ISDN)

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