MPC8560CPXAPDB datasheet(98/108 Pages) FREESCALE

98 / 108 page

MPC8560 Integrated Processor Hardware Specifications, Rev. 3.1

Freescale Semiconductor

System Design Information

Figure 59. Driver Impedance Measurement

The output impedance of the RapidIO port drivers targets 200-

Ω differential resistance. 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 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 60 summarizes the signal impedance targets. The driver impedance are targeted at minimum VDD, nominal

OVDD, 105°C.

17.6 Configuration Pin Muxing

The MPC8560 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 k

Ω 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

Table 60. Impedance Characteristics

Impedance

Local Bus, Ethernet,

DUART, Control,

Configuration, Power

Management

PCI/PCI-X

DDR DRAM

RapidIO

Symbol

Unit

43 Target

25 Target

20 Target

43 Target

25 Target

20 Target

Differential

200 Target

ZDIFF

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

OVDD

OGND

Pad

Data

SW1

SW2

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