CS61304A View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CS61304A

T1/E1 Line Interface

Cirrus Logic 

CS61304A

Parameter

Turns Ratio

Receiver

1:2 CT ± 5%

Primary Inductance

Primary Leakage Inductance

Secondary Leakage Inductance

Interwinding Capacitance

ET-constant

600 µH min. @ 772 kHz

1.3 µH max. @ 772 kHz

0.4 µH max. @ 772 kHz

23 pF max.

16 V-µs min. for T1

12 V-µs min. for E1

Table A2. Transformer Specifications

Transmitter

1:1 ± 1.5 % for 75 Ω E1

1:1.15 ± 5 % for 100 Ω T1

1:1.26 ± 1.5 % for 120 Ω E1

1.5 mH min. @ 772 kHz

0.3 µH max. @ 772 kHz

0.4 µH max. @ 772 kHz

18 pF max.

16 V-µs min. for T1

12 V-µs min. for E1

The receiver transformer has a grounded center

tap on the IC side. Resistors between the RTIP

and RRING pins to ground provide the termina-

tion for the receive line.

CXT6176 crystal be used for T1 applications and

the CXT8192 crystal be used for E1 applications.

Designing for AT&T 62411

The transmitter transformer matches the 75 Ω

transmitter output impedance to the line imped-

ance. Figures A1-A3 show a 0.47 µF capacitor in

series with the transmit transformer primary. This

capacitor is needed to prevent any output stage

imbalance from resulting in a DC current through

the transformer primary. This current might satu-

rate the transformer producing an output offset

level shift.

Transformers

Recommended transmitter and receiver trans-

former specifications are shown in Table A2. The

transformers in Table A3 are recommended for

use with the CS61304A. Refer to the "Telecom

Transformer Selection Guide" for detailed sche-

matics which show how to connect the line

interface IC with a particular transformer.

Selecting an Oscillator Crystal

Specific crystal parameters are required for

proper operation of the jitter attenuator. It is rec-

ommended that the Crystal Semiconductor

DS156PP2

For additional information on the requirements of

AT&T 62411 and the design of an appropriate

system synchronizer, please refer to the Crystal

Semiconductor Application Notes: "AT&T 62411

Design Considerations – Jitter and Synchroniza-

tion" and "Jitter Testing Procedures for

Compliance with AT&T 62411".

Transmit Side Jitter Attenuation

In some applications it is desirable to attenuate

jitter from the signal to be transmitted. A

CS61304A in local loopback mode can be used

as a jitter attenuator. The inputs to the jitter at-

tenuator are TPOS, TNEG, TCLK. The outputs

from the jitter attenuator are RPOS, RNEG and

RCLK.

Line Protection

Secondary protection components can be added

to provide lightning surge and AC power-cross

immunity. Refer to the "Telecom Line Protection

Application Note" for detailed information on the

different electrical safety standards and specific

application circuit recommendations.

29

Share Link: