MT9076AB Просмотр технического описания (PDF) - Mitel Networks

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производитель

MT9076AB

T1/E1/J1 3.3V Single Chip Transceiver

Mitel Networks 

MT9076

Peak to Peak

Jitter Amplitude

(log scale)

18UI

Preliminary Information

MT9076

Tolerance

1.5UI

0.2UI

1.667Hz 20Hz

Jitter Frequency

(log scale)

2.4kHz 18kHz 100kHz

Figure 4 - Input Jitter Tolerance as Recommended by G.823 and ETSI 300 011 (E1)

1.2 Transmitter

The transmit portion of the MT9076 LIU consists of a high speed digital-to-analog converter and

complementary line drivers.

When a pulse is to be transmitted, a sequence of digital values (dependent on transmit equalization) are read

out of a ROM by a high speed clock. These values drive the digital-to-analog converter to produce an analog

signal, which is passed to the complementary line drivers.

The complementary line drivers are designed to drive a 1:2.4 step-up transformer in T1 mode (see Figure 4 for

T1 mode) and either a 1:2 or 1:2.4 step-up transformer in E1 mode (see Figure 5 for E1 mode). A 0.47uF

capacitor is required between the TTIP and the transmit transformer. Resistors RT (as shown in Figure 4) are

for termination for transmit return loss. The values of RT may be optimized for T1 mode, E1 120Ω lines, E1 75Ω

lines or set at a compromise value to serve multiple applications. Program the Tx LIU Control Word (page 02H,

address 11H) to adjust the pulse amplitude accordingly.

Alternatively, the pulse level and shape may be discretely programmed by writing to the Custom Pulse Level

registers (page 2, addresses 1CH to 1FH) and setting the Custom Transmit Pulse bit high (bit 3 of the Tx LIU

Control Word). In this case the output of each of the registers directly drives the D/A converter going to the line

driver. Tables 1 and 2 show recommended transmit pulse amplitude settings.

In T1 mode, the template for the transmitted pulse (the DSX-1 template) is shown in Figure 8. The nominal

peak voltage of a mark is 3 volts. The ratio of the amplitude of the transmit pulses generated by TTIP and

TRING lie between 0.95 and 1.05.

In E1 mode, the template for the transmitted pulse, as specified in G.703, is shown in Figure 8. The nominal

peak voltage of a mark is 3 volts for 120 Ω twisted pair applications and 2.37 volts for 75 Ω coax applications.

The ratio of the amplitude of the transmit pulses generated by TTIP and TRING lie between 0.95 and 1.05.

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