MC68160BFB View Datasheet(PDF) - Motorola => Freescale
Part Name
Description
Manufacturer
MC68160BFB Datasheet PDF : 30 Pages
| |||
MC68160 MC68160B MC68160C
APPLICATIONS INFORMATION
Selection of Crystal and External Components
Accuracy of frequency and stability over temperature are
the main determinants of crystal choice. Specifications for a
suitable crystal are tabulated below.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Frequency
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Mode
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Tolerance
Stability
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Aging
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Shunt Capacitance
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Load Capacitance
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Series Fundamental Resistance (ESR)
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Drive Level
20.000 MHz
Fundamental
± 100 ppm
± 100 ppm
± 5 ppm/yr
7.0 pF
18–20 pF
25 Ω
500 µW
X1
X2
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.
C5
12
C4
Vendor
FEE Fil–Mag
Valor Electronics
Pulse Engineering
TOKO
Part #
78Z1120B–01, 78Z1122B/D–01,
78Z1122 F–01
PT3877, FL1012, FL1066
PE–65434, PE65424, PE65433
PM01–00, PM02–00, PM05–00
AUI Transformer Choice
Like the 10BASE–T outputs, the AUI differential outputs
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.
Vendor
Coilcraft
FEE Fil–Mag
Valor Electronics
Pulse Engineering
TOKO
Part #
LAX–ET304
23Z90, 23Z91/ 23Z92
LT6032, LT6033
PE64502, PE6103
Q30ALQ8–1AA3, Q30ALQ9–1AA3
PLL Filter Components
The filter components at Pin 12 were chosen to assure
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.
+ ǒ Ǔ VCO Gain
24
MHz
Volt • sec
+ ń ǒ Ǔ Phase Detector Gain
100
p2
and,
mA
rad
and the
filter impedance function is;
[ ) ń) ń uu Z(jw)
(jw 1 C6)
jw • C5 • (jw 1 C5) (for C6
C5)
10BASE–T Filter and Transformer Choice
The MC68160, B and C differential outputs are low
impedance 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 Ω, a 39 Ω resistor is
used in series as shown in the applications schematic. So the
impedance presented from the source to the isolation
transformer is then very nearly 100 Ω. The following is a list of
some 10BASE–T filter module vendors and their products.
Application Notes:
The following procedure is applicable to all three versions
MC68160, MC68160B and MC68160C. References to the
MC68160 includes all the versions.
Resetting the MC68160 after power up.
In some applications, after initial power up, the MC68160
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 MC68160 into the production test
mode.
To exit the test mode and return to normal: Set LOOP low,
TPFULDL high and TPSQEL low. Then, while keeping
TPSQEL low, raise LOOP after 300 ms lower TPFULDL. This
will put the MC68160 into test mode but also resets the
MC68160. After 500 ms lower LOOP to get out of the test
mode. TPFULDL may then be de–asserted if desired.
The MC68160 is now ready for operation.
A hardware implementation of this fix would be to place a
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 MC68160 lines
while it is booting up, the reset procedure must be followed.
MOTOROLA ANALOG IC DEVICE DATA
27
Share Link: 