mpc8313e Freescale Semiconductor, Inc, mpc8313e Datasheet - Page 83

• Manufacturer Part Number: mpc8313e
• Description: Mpc8313e Powerquicc Ii Pro Processor
• Manufacturer: Freescale Semiconductor, Inc

Power and ground connections must be made to all external V
and VSS pins of the device.
21.5
The MPC8313E 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 VSS. Then, the value of each resistor is varied until the pad voltage is NV
output 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
The value of this resistance and the strength of the driver’s current source can be found by making two
measurements. First, the output voltage is measured while driving logic 1 without an external differential
termination resistor. The measured voltage is V
while driving logic 1 with an external precision differential termination resistor of value R
measured voltage is V
R
Freescale Semiconductor
term
DD
× (V
/2. R
Output Buffer DC Impedance
1
P
/V
then becomes the resistance of the pull-up devices. R
0
2
for the single-ended drivers, an external resistor is connected from the chip pad to NV
– 1). The drive current is then I
MPC8313E PowerQUICC
2
0
= (1/(1/R
= (R
P
+ R
Figure 41. Driver Impedance Measurement
1
Data
N
+ 1/R
)/2.
2
™
)) × I
II Pro Processor Hardware Specifications, Rev. 0
1
source
source
= R
source
. Solving for the output impedance gives R
= V
2
C).
1
× I
/R
Pad
P
R
source
R
source
is trimmed until the voltage at the pad equals
NV
N
DD
P
VSS
DD
, NV
P
. Second, the output voltage is measured
.
and R
SW2
SW1
DD
, GV
N
are designed to be close to each
DD
DD
, LV
/2 (see
System Design Information
DD
, LV
Figure
term
DDA
. The
41). The
source
, LV
DDB
=
DD
83
,