mpc8378e Freescale Semiconductor, Inc, mpc8378e Datasheet - Page 123

• Manufacturer Part Number: mpc8378e
• Description: Powerquicc Ii Pro Processor Hardware Specifications
• Manufacturer: Freescale Semiconductor, Inc

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
Table 79
nominal OV
24.5
The device provides the user with power-on configuration options which can be set through the use of
external pull-up or pull-down resistors of 4.7 kΩ on certain output pins (see customer visible configuration
pins). These pins are generally used as output only pins in normal operation.
While HRESET is asserted however, these pins are treated as inputs. The value presented on these pins
while HRESET is asserted, is latched when PORESET deasserts, at which time 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 the large value of the pull-up/pull-down resistor should
minimize the disruption of signal quality or speed for output pins thus configured.
24.6
The device requires high resistance pull-up resistors (10 kΩ is recommended) on open drain type pins
including I
For more information on required pull-up resistors and the connections required for the JTAG interface,
see AN3665, “MPC837xE Design Checklist.”
25 Ordering Information
Ordering information for the parts fully covered by this specification document is provided in
Section 25.1, “Part Numbers Fully Addressed by This Document.”
Freescale Semiconductor
Note: Nominal supply voltages. See
term
Impedance
Differential
R
R
× (V
N
P
summarizes the signal impedance targets. The driver impedance are targeted at minimum V
Pull-Up Resistor Requirements
Configuration Pin Muxing
1
2
/V
C pins and IPIC interrupt pins.
DD
2
, 105°C.
– 1). The drive current is then I
Configuration, Power
Local Bus, Ethernet,
DUART, Control,
Management
MPC8378E PowerQUICC II Pro Processor Hardware Specifications, Rev. 3
42 Target
42 Target
2
= (1/(1/R
NA
Table
1
+ 1/R
Table 79. Impedance Characteristics
2, T
(not including PCI
j
= 105°C.
2
output clocks)
)) × I
PCI Signals
25 Target
25 Target
NA
1
source
source
= R
source
. Solving for the output impedance gives R
= V
1
× I
PCI Output Clocks
/R
PCI_SYNC_OUT)
source
source
(including
42 Target
42 Target
NA
. Second, the output voltage is measured
.
DDR DRAM
20 Target
20 Target
NA
Ordering Information
Symbol
Z
term
DIFF
Z
Z
0
0
. The
source
Unit
=
W
W
W
DD
123
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