MPC8358ECVRADDDA datasheet(98/102 Pages) FREESCALE

98 / 102 page

MPC8360E/MPC8358E PowerQUICC II Pro Processor Revision 2.x TBGA Silicon Hardware Specifications, Rev. 5

Freescale Semiconductor

Configuration Pin Muxing

Figure 57. Driver Impedance Measurement

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.

This table summarizes the signal impedance targets. The driver impedance are targeted at minimum VDD, nominal OVDD,

105

° C.

23.6

Configuration Pin Muxing

The device provides the user with power-on configuration options that can be set through the use of external pull-up or

pull-down resistors of 4.7 k

Ωon 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. 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.

Table 79. Impedance Characteristics

Impedance

Local Bus, Ethernet, DUART,

Control, Configuration, Power

Management

PCI

DDR DRAM

Symbol

Unit

42 Target

25 Target

20 Target

42 Target

25 Target

20 Target

Differential

ZDIFF

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

OVDD

OGND

Pad

Data

SW1

SW2

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