mpc8308 Freescale Semiconductor, Inc, mpc8308 Datasheet - Page 83

• Manufacturer Part Number: mpc8308
• Description: Mpc8308 Powerquicc Ii Pro Processor Hardware Specification
• Manufacturer: Freescale Semiconductor, Inc

These decoupling capacitors should receive their power from separate V
V
directly under the device using a standard escape pattern. Others may surround the part.
These capacitors should have a value of 0.01 or 0.1 µF. Only ceramic SMT (surface mount technology)
capacitors should be used to minimize lead inductance, preferably 0402 or 0603 sizes.
In addition, it is recommended that there be several bulk storage capacitors distributed around the PCB,
feeding the V
These bulk capacitors should have a low ESR (equivalent series resistance) rating to ensure the quick
response time necessary. They should also be connected to the power and ground planes through two vias
to minimize inductance. Suggested bulk capacitors are in the range of 100–330 µF (AVX TPS tantalum or
Sanyo OSCON). However, customers should work directly with their power regulator vendor for best
values and types of bulk capacitors.
23.4
To ensure reliable operation, it is highly recommended to connect unused inputs to an appropriate signal
level. Unused active low inputs should be tied to NV
inputs should be connected to VSS. All NC (no-connect) signals must remain unconnected.
Power and ground connections must be made to all external V
and V
23.5
The device drivers are characterized over process, voltage, and temperature. For all buses, the driver is a
push–pull single-ended driver type (open drain for I
To measure Z
or V
impedance is the average of two components: the resistances of the pull-up and pull-down devices. When
data is held high, SW1 is closed (SW2 is open), and R
NV
other in value. Then, Z
Freescale Semiconductor
SS
DD
SS
power planes in the PCB, utilizing short traces to minimize inductance. Capacitors may be placed
SS
/2. R
. Then, the value of each resistor is varied until the pad voltage is NV
pins of the device.
Connection Recommendations
Output Buffer DC Impedance
P
then becomes the resistance of the pull-up devices. R
DD
0
for the single-ended drivers, an external resistor is connected from the chip pad to NV
, NV
MPC8308 PowerQUICC II Pro Processor Hardware Specification, Rev. 1
DD
0
, GV
= (R
DD
P
+ R
, LV
N
)/2.
DD
planes, to enable quick recharging of the smaller chip capacitors.
DD
2
C, MDIO, and HRESET).
P
, GV
is trimmed until the voltage at the pad equals
DD
DD
, and LV
, NV
P
and R
DD
DD
N
, AV
DD
as required. Unused active high
are designed to be close to each
, NV
DD
DD1
/2
DD
, AV
(Figure
, GV
System Design Information
DD2
DD
, GV
55). The output
, LV
DD
DD
, LV
, and
DD
DD
83
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