BT8375 CONEXANT [Conexant Systems, Inc], BT8375 Datasheet - Page 182

• Manufacturer Part Number: BT8375
• Description: single chip transceivers for T1/E1 and Integrated Service Digital Network (ISDN) primary rate interfaces
• Manufacturer: CONEXANT [Conexant Systems, Inc]

3.11 Transmit LIU Registers
3.11 Transmit LIU Registers
Unused bits indicated by a dash (
effect.
SHAPE[5:0]
After writing to TLIU_CR, the processor should wait for eight MCLK-cycles before reading back TLIU_CR.
This is because any write into TLIU_CR triggers an internal transfer of ROM data to update the SHAPE
registers. While this internal transfer is in progress, any read or write of TLIU_CR may be blocked internally or
it will return an incorrect read value.
TURNS
TERM
3-64
060–067—Transmit Pulse Shape Configuration (SHAPE)
068—Transmit LIU Configuration (TLIU_CR)
TURNS
—
7
7
Initialized to default values when the processor writes to addr 068. Refer to pulse shape
description in Transmit LIU section
Transmit Transformer Turns Ratio—Transmit DAC automatically scales the XTIP/XRING
outputs for the selected transformer turns ratio. The transmit DAC is current-limited and
cannot source sufficient current to drive full-height output pulses when an external transmit
termination resistor and 1:1.15 transformer is selected.
Transmit Termination Resistor—Transmit DAC automatically scales the XTIP/XRING output
amplitude to compensate for the presence of an optional external termination resistor. The
external resistor (51.1 ) is placed in parallel across XTIP/XRING on systems that must meet
–18 dB transmitter return loss requirements. Better return loss is also possible by more closely
matching transmitter and cable impedances, at the expense of higher power dissipation and
lower output signal amplitude. (Refer to
Placement
values.)
TERM
—
6
6
for resistor placement. Refer to
SHAPE[5]
LBO[1]
—
5
5
) are reserved and should be written to 0. Writing to reserved bits has no
0 = 1:1.36 transformer
1 = 1:1.15 transformer (reduced amplitude if TERM also enabled)
0 = internal transmit impedance (14.0 k )
1 = external transmit termination
SHAPE[4]
LBO[0]
4
4
Conexant
(Figure 2-39, Digitized AMI Pulse
Figure 2-45, External Termination Resistor
SHAPE[3]
PULSE[2]
Table 3-14, Return Loss Values
3
3
Fully Integrated T1/E1 Framer and Line Interface
SHAPE[2]
PULSE[1]
2
2
SHAPE[1]
PULSE[0]
Shape).
Bt8370/8375/8376
1
1
for return loss
N8370DSE
SHAPE[0]
AISCLK
0
0