mpc8544e Freescale Semiconductor, Inc, mpc8544e Datasheet - Page 109

• Manufacturer Part Number: mpc8544e
• Description: Mpc8544e Powerquicc Iii Integrated Processor
• Manufacturer: Freescale Semiconductor, Inc

resistance of the pull-up devices. R
Z
Table 73
nominal OV
21.8
The MPC8544E 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 HRESET deasserts, at which time the input receiver is disabled
and the I/O circuit takes on its normal function. Most of these sampled configuration pins are equipped
with an on-chip gated resistor of approximately 20 kΩ. This value should permit the 4.7-kΩ resistor to pull
the configuration pin to a valid logic low level. The pull-up resistor is enabled only during HRESET (and
for platform /system clocks after HRESET deassertion to ensure capture of the reset value). When the input
receiver is disabled the pull-up is also, thus allowing functional operation of the pin as an output with
minimal signal quality or delay disruption. The default value for all configuration bits treated this way has
Freescale Semiconductor
Note: Nominal supply voltages. See
0
= (R
Impedance
P
R
R
+ R
summarizes the signal impedance targets. The driver impedances are targeted at minimum V
N
P
Configuration Pin Muxing
DD
N
) ÷ 2.
, 90°C.
MPC8544E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 4
Control, Configuration, Power
Local Bus, Ethernet, DUART,
Management
43 Target
43 Target
Table
Figure 67. Driver Impedance Measurement
Data
Preliminary—Subject to Change Without Notice
Table 73. Impedance Characteristics
P
1.
and R
Freescale Confidential Proprietary
N
are designed to be close to each other in value. Then,
25 Target
25 Target
PCI
Pad
R
R
OV
OGND
N
P
DD
SW2
SW1
DDR DRAM
20 Target
20 Target
System Design Information
Symbol
Z
Z
0
0
Unit
W
W
DD
109
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