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Maxim > Design Support > Technical Documents > Application Notes > T/E Carrier and Packetized > APP 3619
Keywords: T1, E1, transmit pulse, template
APPLICATION NOTE 3619
DS26334 and DS26324 Transmit Pulse Control
Sep 16, 2005
Abstract: The DS26334 and DS26324 line interface units (LIUs) contain precise methods for making
minor or major changes to the output pulse. This application note provides the information required to
access factory test registers that allow the transmit waveform to be modified to meet a wide variety of
application requirements.
With the addition of network-protection components and/or the need to route signals through connectors
and other PCB requirements, it is sometimes necessary to manipulate the transmit waveform.
T1 and E1 Transmit Waveform Programmable Sections
The DS26334 and DS26324 contain registers that provide control for the transmit pulse in two major
areas, amplitude and timing. T1 and E1 transmit pulses are divided into sections, each of which can be
manipulated to provide the desired waveform. Figure 1 shows how the T1 pulse is divided and the
registers that control each section. Figure 2 provides the same information for the E1 pulse.
T1 and E1 Transmit Waveform Amplitude Control
The amplitude of the DS26334 and DS26324 transmit pulse can be controlled in two ways.
1. Adjusting the DAC gain
The LITXLAE register bits DAC[3:0] provide positive and negative adjustment of all the T1 or E1
levels simultaneously.
2. Partial waveform level adjustment
The WLA[3:0] bits of the level adjustment registers provide fine-tuning of specific sections of the
waveform. The step size of the voltage level will change in proportion to the programmed DAC gain.
If the DAC gain is increased by 10%, the step sizes will also increase by 10%.
T1 and E1 Transmit Waveform Timing Control
The timing of the DS26334 and DS26324 transmit pulse levels are controlled by the CEA[2:0] bits of the
level adjustment registers. Each edge can be moved in both positive and negative directions in
increments of 1/32 of TCLK.
General Recommendations
Modifying the DAC gain is the easiest method of controlling the amplitude of the transmit pulse because
it will control the entire waveform with only one register change. Using the DAC gain first will allow for
minimal (if any) modifications of the individual level adjustment registers.
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