ds26518 Maxim Integrated Products, Inc., ds26518 Datasheet - Page 83

• Manufacturer Part Number: ds26518
• Description: 8-port T1/e1/j1 Transceiver
• Manufacturer: Maxim Integrated Products, Inc.

9.12.2 Transmitter
NRZ data arrives from the framer transmitter; the data is encoded with HDB3 or B8ZS or AMI. The encoded data
passes through a jitter attenuator if it is enabled for the transmit path. A digital sequencer and DAC are used to
generate transmit waveforms compliant with T1.102 and G.703 pulse templates.
A line driver is used to drive an internal matched impedance circuit for provision of 75:, 100:, 110:, and 120:
terminations. The transmitter couples to the E1 or T1 transmit twisted pair (or coaxial cable in some E1
applications) via a 1:2 step-up transformer. In order for the device to create the proper waveforms, the transformer
used must meet the specifications listed in
E1 or 1.544MHz for T1/J1 operation.
The DS26518 drivers have a short-circuit and open-circuit detection driver-fail monitor. The TXENABLE pin can
high impedance the transmitter outputs for protection switching. The individual transmitters can also be placed in
high impedance through register settings. The DS26518 also has functionality for powering down the transmitters
individually. The relevant telecommunications specification compliance is shown in
Table 9-39. Telecommunications Specification Compliance for DS26518 Transmitters
Table 9-40. Transformer Specifications
Turns Ratio 3.3V Applications
Primary Inductance
Leakage Inductance
Intertwining Capacitance
Transmit Transformer DC
Resistance
Receive Transformer DC
Resistance
Transmission and Return Loss Compliance
T1 Telecom Pulse Template Compliance
T1 Telecom Pulse Template Compliance
Transmit Electrical Characteristics for E1
TRANSMITTER FUNCTION
SPECIFICATION
Primary (Device Side)
Secondary
Primary (Device Side)
Secondary
Table
9-40. The transmitter requires a transmit clock of 2.048MHz for
83 of 286
TELECOMMUNICATIONS COMPLIANCE
1:1 (receive) and 1:2 (transmit) ±2%
RECOMMENDED VALUE
600PH minimum
1.0PH maximum
40pF maximum
1.0: maximum
2.0: maximum
1.2: maximum
1.2: maximum
ANSI T1.403
ANSI T1.102
ITU-T G.703
DS26518 8-Port T1/E1/J1 Transceiver
Table
9-39.