AN728 データシートの表示（PDF） - Vishay Semiconductors

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Designing A Flyback Converter with Si9113 for Feeding the TE from U-Interface In ISDN

Vishay Semiconductors 

AN728

Vishay Siliconix

VIN = 48 V

IO @ 3.3 V = Step – 12 to 120 mA

IO @ 40 V = 12 mA

Ch1: VO = 3.3 V (50 mV/div)

Ch4: IO = 3.3 V (50 mA/div)

FIGURE 10. Transient Response—Main Output (3.3 V)

ISDN CONCEPT

Integrated Services Digital Network (ISDN) is a combination of

technology standards and regulations for digital

telecommunications first proposed by the international

telecommunications regulatory body, CCITT, in 1980.

Intended to enable end-to-end digital communication of voice

and data, the ISDN subscriber loop is key to the successful

ISDN implementation because it must:

D Provide the user with a flexible digital interface with

access to a wide variety of present and future services;

D Allow the evolution of the individual network services to

progress towards achieving an ISDN according to the

different strategies of the networks operators.

In analog transmission systems, the transmitted signals may

represent analog or digital data. In either case, the signals are

subject to attenuation, limiting the length of the transmission

link. Even with repeaters, the signal-to-noise ratio still suffers

over long distances. Digital signals, by contrast, are

significantly more accurate.

Most of today’s public switched telephone networks (PSTN)

are digital, but the connection to end-customer telephone

equipment—often called the subscriber loop—mostly

employs analog techniques. The connection becomes

dedicated for the duration of a call. For data terminals, packet

switching is commonly used to support multiple logical

connections and thus makes more efficient use of the

connection bandwidth. Similar to the telephone network, the

telex network also uses circuit switching but at a much slower

speed. Consequently there is a tremendous pressure to

integrate the series to achieve an efficient digital network.

As shown in Figure 11, the ISDN central office connects the

numerous subscriber loops to the digital network. This

provides access to a variety of lower OSI layers.

Phone

ISDN

Subscriber

Loop

PC

Special Terminal

ISDN

Exchange

Telex

Telephone Network

Packet -Switched Data Network

Telex Network

Signaling Network

ISDN

Subscriber

Loop

Phone

ISDN

Exchange

PC

Special Terminal

Telex

Document Number: 71120

29-Feb-00

FIGURE 11. Integrated Digital Network

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