mpc8343e Freescale Semiconductor, Inc, mpc8343e Datasheet - Page 76

• Manufacturer Part Number: mpc8343e
• Description: Mpc8343e Powerquicc
• Manufacturer: Freescale Semiconductor, Inc

System Design Information
Two measurements give the value of this resistance and the strength of the driver current source. First, the
output voltage is measured while driving logic 1 without an external differential termination resistor. The
measured voltage is V
with an external precision differential termination resistor of value R
V
drive current is then I
Table 57
nominal OV
21.6
The MPC8343E power-on configuration options can be set through external pull-up or pull-down resistors
of 4.7 kΩ on certain output pins (see the customer-visible configuration pins). These pins are used as
output only pins in normal operation.
However, while HRESET is asserted, these pins are treated as inputs, and the value on these pins is latched
when PORESET deasserts. Then the input receiver is disabled and the I/O circuit takes on its normal
function. Careful board layout with stubless connections to these pull-up/pull-down resistors coupled with
76
Note: Nominal supply voltages. See
2
Impedance
Differential
= (1/(1/R
R
R
N
P
summarizes the signal impedance targets. The driver impedance are targeted at minimum V
Configuration Pin Multiplexing
MPC8343E PowerQUICC™ II Pro Integrated Host Processor Hardware Specifications, Rev. 11
DD
1
+ 1/R
, 105°C.
Configuration, Power
Local Bus, Ethernet,
DUART, Control,
2
Management
)) × I
source
42 Target
42 Target
1
= R
NA
source
= V
source
. Solving for the output impedance gives R
Table
1
Figure 37. Driver Impedance Measurement
/R
× I
Data
source
Table 57. Impedance Characteristics
1, T
source
(Not Including PCI
j
.
= 105°C.
Output Clocks)
. Second, the output voltage is measured while driving logic 1
PCI Signals
25 Target
25 Target
NA
PCI Output Clocks
PCI_SYNC_OUT)
Pad
R
R
(Including
N
P
OV
OGND
42 Target
42 Target
DD
NA
SW2
SW1
term
. The measured voltage is
source
DDR DRAM
20 Target
20 Target
= R
NA
term
Freescale Semiconductor
× (V
Symbol
Z
1
DIFF
Z
Z
/V
0
0
2
– 1). The
Unit
Ω
Ω
Ω
DD
,