MPC8349E View Datasheet(PDF) - Freescale Semiconductor

Part Name

Description

Manufacturer

MPC8349E

PowerQUICC™ II Pro Integrated Host Processor Hardware Specifications

Freescale Semiconductor 

Data

OVDD

RN

SW2

Pad

SW1

RP

System Design Information

OGND

Figure 41. Driver Impedance Measurement

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 V1 = Rsource × Isource. Second, the output voltage is measured while driving logic 1

with an external precision differential termination resistor of value Rterm. The measured voltage is

V2 = (1/(1/R1 + 1/R2)) × Isource. Solving for the output impedance gives Rsource = Rterm × (V1/V2 – 1). The

drive current is then Isource = V1/Rsource.

Table 61 summarizes the signal impedance targets. The driver impedance are targeted at minimum VDD,

nominal OVDD, 105°C.

Table 61. Impedance Characteristics

Impedance

Local Bus, Ethernet,

DUART, Control,

Configuration, Power

Management

PCI Signals

PCI Output Clocks

(Not Including PCI

(Including

DDR DRAM

Output Clocks) PCI_SYNC_OUT)

Symbol

Unit

RN

RP

Differential

42 Target

42 Target

NA

25 Target

25 Target

NA

Note: Nominal supply voltages. See Table 1, Tj = 105°C.

42 Target

42 Target

NA

20 Target

Z0

Ω

20 Target

Z0

Ω

NA

ZDIFF

Ω

21.6 Configuration Pin Multiplexing

The MPC8349E 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

MPC8349E PowerQUICC™ II Pro Integrated Host Processor Hardware Specifications, Rev. 10

Freescale Semiconductor

81

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