CS61884 datasheet(53/72 Pages) CIRRUS

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CS61884

DS485PP4

18.1 Transformer specifications

Recommended

transformer

specifications

are

shown in Table 12. Any transformer used with the

CS61884 should meet or exceed these specifica-

tions.

18.2 Crystal Oscillator Specifications

When a reference clock signal is not available, a

CMOS crystal oscillator may be used as the refer-

ence clock signal. The oscillator must have a mini-

mum symmetry of 40-60% and minimum stability

of + 100ppm for both E1 and T1/J1 applications.

18.3 Designing for AT&T 62411

For information on requirements of the AT&T

62411 and the design of the appropriate system

synchronizer, refer to Application Note AN012

“AT&T 62411 Design Considerations - Jitter and

Synchronization” and Application Note AN011

“Jitter Testing Procedures for Compliance with

AT&T 62411”.

18.4 Line Protection

Secondary protection components can be added to

the line interface circuitry to provide lightning

surge and AC power-cross immunity. For addition-

al information on the different electrical safety

standards and specific applications circuit recom-

mendations, refer to Application Note AN034

“Secondary Line Protection for T1 and E1 Cards”.

Table 12. Transformer Specifications

Descriptions

Specifications

Turns Ratio Receive/Trans-

mit

1:2

Primary Inductance

1.5mH min. @ 772 kHz

Primary Leakage Induc-

tance

0.3

µH max @ 772 kHz

Secondary leakage Induc-

tance

0.4

µH max @ 772 kHz

Inter winding Capacitance

18pF max, primary to

secondary

ET-Constant

16V -

µsmin.

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