BT8954 CONEXANT [Conexant Systems, Inc], BT8954 Datasheet - Page 20

• Manufacturer Part Number: BT8954
• Description: VOICE PAIR GAIN FRAMER
• Manufacturer: CONEXANT [Conexant Systems, Inc]

2.0 Pin Descriptions
Table 2-1. Hardware Signal Definitions (2 of 4)
2-4
BCLK
QCLK
TDAT
RDAT
BCLK_REP
QCLK_REP
Pin Label
Number
Pin
10
11
6
4
5
7
Bit Clock
Quaternary Clock
Transmit Data
Receive Data
BCLK from destination
bit pump in a repeater
terminal
QCLK from destination
bit pump in a repeater
terminal
Signal Name
Conexant
I/O
O
I
I
I
I
I
Corresponds to the DSL channel. BCLK operates at the 2B1Q
symbol rate. The rising edge of BCLK outputs 2x TDAT. The
falling edge of BCLK samples QCLK at the RDAT input. (In
the repeater terminal, BCLK is the BCLK from the bit pump to
which RDAT is connected.)
NOTE(S):
The BCLK signal from the bit-pump to the channel unit
device is sensitive to overshoot and undershoot. The BCLK
sensitivity could cause bit-errors in the system. A 100
series terminating resistor might be required to help dampen
the overshoot and undershoot. The bit-pump line cards
include a 74HCT244 to drive the long traces through the
motherboard 96-pin connectors.
Operates at the 2B1Q symbol rate (1/2 bit rate) and identifies
sign and magnitude alignment of both the RDAT and TDAT
serially encoded bit streams.
1 = magnitude bit. In the Repeater Terminal, BCLK is the
BCLK from the bit pump to which RDAT is connected.
DSL transmit data output at the bit rate on the rising edge of
BCLK. Serially encoded with the 2B1Q sign bit aligned to the
QCLK low level and the 2B1Q magnitude bit aligned to the
QCLK high level.
DSL receive data input sampled on the falling edge of BCLK.
The serially encoded 2B1Q sign bit is sampled when QCLK is
low, and the 2B1Q magnitude bit is sampled when QCLK is
high.
BCLK from the bit pump to which the Bt8954 TDAT is
connected in a repeater terminal. It is used only in the
repeater mode and should be tied to VDD or GND in
non-repeater terminals.
QCLK from the bit pump to which the Bt8954 TDAT is
connected in a repeater terminal. It is used only in the
repeater mode and should be tied to VDD or GND in
non-repeater terminals.
The falling edge of BCLK samples QCLK: 0 = sign bit;
Refer to Appendix A, page 81.
Definition
Voice Pair Gain Framer
N8954DSC
Bt8954