mc68160b Freescale Semiconductor, Inc, mc68160b Datasheet - Page 24

• Manufacturer Part Number: mc68160b
• Description: Enhanced Ethernet Transceiver
• Manufacturer: Freescale Semiconductor, Inc

Selection of Crystal and External Components
the main determinants of crystal choice. Specifications for a
suitable crystal are tabulated below.
PLL Filter Components
adequate pull–range but with a emphasis on stability. It is not
foreseeable that a design would need to change the
components, but for the sake of completeness, relevant
values are provided here.
filter impedance function is;
10BASE–T Filter and Transformer Choice
voltage sources. Therefore, external series resistors must be
used in order to match the characteristic impedance of
twisted pair. Since the output resistance of each leg of the
transmitter is about 10 , a 39
shown in the applications schematic. So the impedance
presented from the source to the isolation transformer is then
very nearly 100 . The following is a list of some 10BASE–T
filter module vendors and their products.
A suitable crystal is the MTRON
HC49 MP–1, 20.000 MHz crystal.
20 pF for C4 and C5 have been
shown to work reliably.
Frequency
Mode
Tolerance
Stability
Aging
Shunt Capacitance
Load Capacitance
Series Fundamental Resistance (ESR)
Drive Level
VCO Gain
Phase Detector Gain
Z(j
24
Accuracy of frequency and stability over temperature are
The filter components at Pin 12 were chosen to assure
The MC68160B differential outputs are low impedance
w
)
[
j
w
+
(j
C5 (j
24
w
)
Volt
w
1 C6)
MHz
+
)
1 C5)
100
p
sec
2
and,
resistor is used in series as
rad
m
(for C6
A
C 5
and the
X1
uu
APPLICATIONS INFORMATION
Fundamental
1
20.000 MHz
C5)
18–20 pF
500 W
100 ppm
100 ppm
5 ppm/yr
7.0 pF
25
2
X2
MC68160B
C 4
AUI Transformer Choice
are low impedance sources and capable of meeting the IEEE
802.3 waveform requirements when a coupling transformer
is used. Some AUI transformer vendors and their products
are provided below.
Application Notes:
may not be able to transmit or receive data. This is usually
caused by the LOOP and TPFULDL control lines being active
at the same time. This is an illegal condition during normal
operation, it places the MC68160B into the production test
mode.
TPFULDL high and TPSQEL low. Then, while keeping
TPSQEL low, raise LOOP after 300 ms lower TPFULDL. This
will put the MC68160B into test mode but also resets the
MC68160B. After 500 ms lower LOOP to get out of the test
mode. TPFULDL may then be de–asserted if desired.
pull down resistor on the TPSQEL pin. Even if test mode is
entered by accident, this ensures that zero’s will be written to
the test register. The hardware implementation will solve the
problem if the test mode is entered because of noise on the
TPSQEL pin. If the controller is toggling the MC68160B lines
while it is booting up, the reset procedure must be followed.
Vendor
FEE Fil–Mag
Valor Electronics
Pulse Engineering
TOKO
Vendor
Coilcraft
FEE Fil–Mag
Valor Electronics
Pulse Engineering
TOKO
a o
Like the 10BASE–T outputs, the AUI differential outputs
Resetting the MC68160B after power up.
In some applications, after initial power up, the MC68160B
To exit the test mode and return to normal: Set LOOP low,
The MC68160B is now ready for operation.
A hardware implementation of this fix would be to place a
ec o cs
MOTOROLA ANALOG IC DEVICE DATA
Part #
78Z1120B–01, 78Z1122B/D–01,
78Z1122 F–01
78Z1122 F–01
PT3877, FL1012, FL1066
PE–65434, PE65424, PE65433
PM01–00, PM02–00, PM05–00
Part #
LAX–ET304
23Z90, 23Z91/ 23Z92
LT6032, LT6033
PE64502, PE6103
Q30ALQ8–1AA3, Q30ALQ9–1AA3
38
,
0
,
066