CS61304A データシートの表示（PDF） - Cirrus Logic

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CS61304A

T1/E1 Line Interface

Cirrus Logic 

CS61304A

CS61304A

Transmitter

The transmitter takes digital T1 or E1 input data

and drives appropriately shaped bipolar pulses

onto a transmission line. The transmit data (TPOS

& TNEG or TDATA) is supplied synchronously

and sampled on the falling edge of the input

clock, TCLK.

Either T1 (DSX-1 or Network Interface) or E1

CCITT G.703 pulse shapes may be selected.

Pulse shaping and signal level are controlled by

"line length select" inputs as shown in Table 3.

The output options in Table 3 are specified with a

1:1.15 transmitter transformer turns ratio for T1

and a 1:1 turns ratio for E1 without external series

resistors. Other turns ratios may be used if ap-

proriate resistors are placed in series with the

TTIP and TRING pins. Table A1 in the applica-

tions section lists other combinations which can

be used to provide transmitter impedance match-

ing.

For T1 DSX-1 applications, line lengths from 0 to

655 feet (as measured from the transmitter to the

DSX-1 cross connect) may be selected. The five

partition arrangement in Table 3 meets ANSI

T1.102 and AT&T CB-119 requirements when

using #22 ABAM cable. A typical output pulse is

shown in Figure 8. These pulse settings can also

be used to meet CCITT pulse shape requirements

for 1.544 MHz operation.

For T1 Network Interface applications, two addi-

tional options are provided. Note that the optimal

pulse width for Part 68 (324 ns) is narrower than

the optimal pulse width for DSX-1 (350 ns). The

CS61304A automatically adjusts the pulse width

based upon the "line length" selection made.

The E1 G.703 pulse shape is supported with line

length selections LEN2/1/0 = 0/0/0 and 0/0/1.

The pulse width will meet the G.703 pulse shape

template shown in Figure 9, and specified in Ta-

ble 4.

10

LEN2 LEN1 LEN0 Option Selected Application

0

1

1

1

0

0

1

0

1

1

1

0

1

1

1

0-133 ft

133-266 ft

266-399 ft

399-533 ft

533-655 ft

DSX-1

ABAM

(AT&T 600B

or 600C)

0

0

0

75Ω coax

E1

0

0

1

120Ω twisted-pair CCITT G.703

0

1

0 FCC PART 68, OPT. A Network

0

1

1

ANSI T1.403

Interface

Table 3. Line Length Selection

The CS61304A transmitter provides short-circuit

current limiting protection and meets OFTEL

OTR-001 short-circuit current limiting require-

ments for E1 applications.

The CS61304A will detect a static TCLK, and

will force TTIP and TRING low to prevent trans-

mission when data is not present. When any

transmit control pin (TAOS, LEN0-2 or LLOOP)

is toggled, the transmitter outputs will require ap-

proximately 22 bit periods to stabilize. The

transmitter will take longer to stabilize when

RLOOP is selected because the timing circuitry

must adjust to the new frequency.

NORMALIZED

AMPLITUDE

1.0

0.5

ANSI T1.102,

AT&T CB 119

SPECIFICATIONS

0

-0.5

0

OUTPUT

PULSE SHAPE

250

500

750

TIME (nanoseconds)

1000

Figure 8. Typical Pulse Shape at DSX-1 Cross Connect

DSD1S5165P6PF21

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