Ordering Information
V = (1 ÷ (1/R + 1/R )) × I
. Solving for the output impedance gives R
= R
× (V ÷ V – 1).
2
1
2
source
source
term 1 2
The drive current is then I
= V ÷ R
.
source
1
source
Table 65 summarizes the signal impedance targets. The driver impedance are targeted at minimum V
,
DD
nominal OV , 105°C.
DD
Table 65. Impedance Characteristics
Local Bus, Ethernet,
PCI Signals
(Not Including PCI
Output Clocks)
PCI Output Clocks
(Including
PCI_SYNC_OUT)
DUART, Control,
Configuration, Power
Management
Impedance
DDR DRAM Symbol
Unit
R
R
42 Target
42 Target
NA
25 Target
25 Target
NA
42 Target
42 Target
NA
20 Target
20 Target
NA
Z0
Z0
W
W
W
N
P
Differential
ZDIFF
Note: Nominal supply voltages. See Table 1, Tj = 105°C.
21.6 Configuration Pin Multiplexing
The MPC8349EA 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
the large value of the pull-up/pull-down resistor should minimize the disruption of signal quality or speed
for the output pins.
21.7 Pull-Up Resistor Requirements
The MPC8349EA requires high resistance pull-up resistors (10 kΩ is recommended) on open-drain pins,
2
including I C pins, and IPIC interrupt pins.
For more information on required pull-up resistors and the connections required for the JTAG interface,
refer to application note AN2931, “PowerQUICC Design Checklist.”
22 Ordering Information
This section presents ordering information for the device discussed in this document, and it shows an
example of how the parts are marked.
NOTE
The information in this document is accurate for revision 3.x silicon and
later (in other words, for orderable part numbers ending in A or B). For
information on revision 1.1 silicon and earlier versions, see the MPC8349E
PowerQUICC II Pro Integrated Host Processor Hardware Specifications
(Document Order No. MPC8349EEC).
MPC8349EA PowerQUICC II Pro Integrated Host Processor Hardware Specifications, Rev. 13
82
Freescale Semiconductor
FREESCALE [ Freescale ]
