MC34055DW View Datasheet(PDF) - Motorola => Freescale
Part Name
Description
Manufacturer
MC34055DW Datasheet PDF : 16 Pages
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MC34055
FUNCTIONAL DESCRIPTION
Introduction
The Motorola 10BASE–T transceiver, designed to comply
with the ISO 8802–3[IEEE 802.3] 10BASE–T specification,
will support one Medium Dependent Interface (MDI) through
standard 10BASE–T filters and transformers. Although the
device is capable of being used in embedded or external
Medium Attachment Units (MAU), it was primarily designed
for use in repeater or hub applications. For this reason a
digital interface is provided rather than an AUI interface. This
interface is TTL, CMOS, and raised ECL compatible and
allows for easy connection in hub applications.
Other features of the MC34055 include: select mode pins
of forcing Loop–Back and Full–Duplex operation; a Signal
Quality Error pin for testing the collision detect circuitry
without affecting the twisted pair output; and LED drivers for
Link Integrity status; Collision detection; and Jabber
detection. An on chip oscillator, capable of receiving a clock
input or operating under crystal control, is also provided for
internal timing and driving a buffered clock output.
Data Transmission
For data intended for the twisted pair, the MC34055 has
two data inputs, TX Data A and TX Data B. TX Data A is
CMOS compatible and TX Data B is raised ECL compatible.
The inputs were not intended to be used simultaneously in a
single application and are internally logically combined. The
unused input should be disabled by connection to VCC.
When data transmission is intended, the MC34055
detects the first falling edge of the Manchester encoded
frame at the input being used, synchronizes the on chip
oscillator (Pins 23 and 24) and asserts the twisted pair driver
output to full differential amplitude within 25 ns if the driver
enable pin (TX EN H) is previously asserted. Also, since
twisted pair attenuates a 10 MHz signal more than a 5.0 MHz
signal the 10BASE–T standard requires that data applied to
the twisted pair receive pre–equalization. To fulfill this
requirement the MC34055 provides an additional 730 mV for
approximately 50 ns to output data. This is accomplished
over the single pair of differential driver pins. TX+ and TX–,
and effectively equalizes the power of all data components at
the receiver. Figure 7A shows a 10 MHz waveform. Figure 7B
shows the effect of pre–emphasis on a 5.0 MHz waveform.
Manchester encoded data with the pattern shown in Figure
7A would represent a repeating pattern of zeros (000000...).
Figure 7B would represent an alternating pattern of ones and
zeros (0101010...).
Figure 7A. 10 MHz Waveform on Differential Outputs
Bit Pattern
0
0
0
TX+ 1.25 Vp–p
Pin 21
0
0
0
0V
TX– 1.25 Vp–p
Pin 20
0V
Figure 7B. 5.0 MHz Waveform on Differential Outputs
Bit Pattern
0
1
0
1
0
TX+
Pin 21
0V
1.25 Vp–p
50 ns
0.885 Vp–p
TX–
Pin 20
0V
0.50 ns
1.25 Vp–p
0.885 Vp–p
8
MOTOROLA ANALOG IC DEVICE DATA
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