XRT83SL38IB datasheet(30/88 Pages) EXAR

30 / 88 page

XRT83SL38

OCTAL T1/E1/J1 SH TRANSCEIVER WITH CLOCK RECOVERY AND JITTER ATTENUATOR

REV. 1.0.2

ARBITRARY PULSE GENERATOR FOR T1 AND E1

The arbitrary pulse generator divides the pulse into eight individual segments. Each segment is set by a 7-Bit

binary word by programming the appropriate channel register. This allows the system designer to set the

overshoot, amplitude, and undershoot for a unique line build out. The MSB (bit 7) is a sign-bit. If the sign-bit is

set to “1”, the segment will move in a positive direction relative to a flat line (zero) condition. If this sign-bit is set

to “0”, the segment will move in a negative direction relative to a flat line condition. A pulse with numbered

segments is shown in Figure 8.

By default, the arbitrary segments are programmed to 0x00h. The transmitter outputs will result in an all zero pattern to the

line. For E1 arbitrary mode, see global register 0xC0h.

TRANSMITTER

DIGITAL DATA FORMAT

Both the transmitter and receiver can be configured to operate in dual or single-rail data formats. This feature is

available under both Hardware and Host control modes, on a global basis. The dual or single-rail data format

is determined by the state of the SR/DR pin in Hardware mode or SR/DR interface bit in the Host mode. In

single-rail mode, transmit clock and NRZ data are applied to TCLK_n and TPOS_n/TDATA_n pins respectively.

In single-rail and Hardware mode the TNEG_n/CODES_n input can be used as the CODES function. With

TNEG_n/CODES_n tied “Low”, HDB3 or B8ZS encoding and decoding are enabled for E1 and T1 modes

respectively. With TNEG_n/CODES_n tied “High”, the AMI coding scheme is selected. In both dual or single-

rail modes of operations, the transmitter converts digital input data to a bipolar format before being transmitted

to the line.

TRANSMIT CLOCK (TCLK) SAMPLING EDGE

Serial transmit data at TPOS_n/TDATA_n and TNEG_n/CODES_n are clocked into the XRT83SL38 under the

synchronization of TCLK_n. With a “0” written to the TCLKE interface bit, or by pulling the TCLKE pin “Low”,

input data is sampled on the falling edge of TCLK_n. The sampling edge is inverted with a “1” written to TCLKE

interface bit, or by connecting the TCLKE pin “High”.

FIGURE 8. ARBITRARY PULSE SEGMENT ASSIGNMENT

Segment

0xn8

0xn9

0xna

0xnb

0xnc

0xnd

0xne

0xnf

XRT83SL38IB Datasheet(PDF) 30 Page - Exar Corporation