CS61582 データシートの表示（PDF） - Cirrus Logic

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CS61582

Dual T1/E1 Line Interface

Cirrus Logic 

NORM ALIZED

A M P LIT U D E

1.0

0.5

ANSI T1.102

S P E C IF IC A T IO N

Percent of

nom inal

peak

voltage

120

110

100

90

80

269 ns

244 ns

194 ns

G .70 3

S P E C IF IC A T IO N

0

-0.5

0

CS61582

OUTPUT

PULSE SHAPE

250

500

750

TIM E (nanoseconds)

1000

Figure 5. Typical Pulse Shape at DSX-1 Cross Connect

matically adjusts the pulse width based on the

configuration selection.

The transmitter impedance changes with the line

length options in order to match the load imped-

ance (75Ω for E1 coax, 100Ω for T1, 120Ω for

E1 shielded twisted pair), providing a minimum

of 14 dB return loss for T1 and E1 frequencies

during the transmission of both marks and

spaces. This improves signal quality by minimiz-

ing reflections from the transmitter. Impedance

matching also reduces load power consumption

by a factor of two when compared to the return

loss achieved by using external resistors.

The CS61582 driver will automatically detect an

inactive TLCK input (i.e., no valid data is being

clocked to the driver). When this condition is de-

tected, the driver is forced low (except during

remote loopback) to output spaces and prevent

TTIP and TRING from entering a constant trans-

mit-mark state.

When the transmit configuration established by

CON[2:0], TAOS, or LLOOP changes state, the

transmitter stabilizes within 22 TCLK bit peri-

ods. The transmitter takes longer to stabilize

when RLOOP1 or RLOOP2 is selected because

50

10

0

-10

-20

219 ns

488 ns

Nominal Pulse

Figure 6. Pulse Mask at the 2048 kbps Interface

the timing circuitry must adjust to the new fre-

quency from RCLK.

When the transmitter transformer secondaries are

shorted through a 0.5 ohm resistor, the transmit-

ter will output a maximum of 50 mA-rms, as

required by European specification BS6450.

RECEIVER

The receiver extracts data and clock from the

T1/E1 signal on the line interface and outputs

clock and synchronized data to the system. The

signal is detected differentially across the receive

transformer and can be recovered over the entire

range of short haul cable lengths. The transmit

and receive transfomer specifications are identical

and are presented in the Applications section.

As shown in Table 1, the receiver slicing level is

set at 65% for DS1/DSX-1 short-haul and at

50% for all other applications.

10

DS224PP1

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