BT8376EPF datasheet(102/323 Pages) CONEXANT

102 / 323 page

2.0 Circuit Description

Bt8370/8375/8376

2.9 Transmit Line Interface Unit

Fully Integrated T1/E1 Framer and Line Interface

2-74

Conexant

N8370DSE

The pulse shape block receives P and N rail NRZ data. For each mark, it

produces a set of eight 6-bit values which define the pulse shape to be transmitted,

as illustrated in Figure 2-39. One of eight preprogrammed pulse shapes is

selected via the Transmit LIU Configuration register [TLIU_CR; addr 068]. The

TLIU control circuit downloads the code values associated with the selected pulse

shape from the ROM to the Transmit Pulse Shape Configuration registers

[SHAPE; addr 060–067], whenever the TLIU register is written to or when the

device is reset. The SHAPE registers can be directly accessed via the

microprocessor interface when a custom pulse shape is desired.

NOTE:

Any modification to the TLIU register initiates another download to the

SHAPE registers. The data stored in the pulse shape ROM and the SHAPE

registers is 5-bit magnitude only.

The TLIU control circuit converts the 5-bit magnitude to 6-bit 2's complement

data. The first 4 code values of the pulse (first half of the symbol) are forced to be

positive, and the last 4 values (last half of the symbol) are forced to be negative,

with respect to output pulse polarity.

Figure 2-39. Digitized AMI Pulse Shape

0 1 2 3 4 5 6 7

0 123 4 5 6 7

0 1 234 5 6 7 0

Shape Data

Magnitude

0x00–0x1F

Positive Pulse

No Pulse

Negative Pulse

TCKO

8TCKO

ShapeAddr [060–067]

Digitized

AMI Pulses

BT8376EPF Datasheet(PDF) 102 Page - Synaptics Incorporated.