56855 datasheet(23/52 Pages) FREESCALE

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AC Electrical Characteristics

56855 Technical Data, Rev. 6

Freescale Semiconductor

Figure 4-3 Example Circuit to Control Supply Sequencing

4.4 AC Electrical Characteristics

Timing waveforms in Section 4.2 are tested with a VIL maximum of 0.8 V and a VIH minimum of 2.0 V

for all pins except XTAL, which is tested using the input levels in Section 4.2. In Figure 4-4 the levels of

VIH and VIL for an input signal are shown.

Figure 4-4 Input Signal Measurement References

Figure 4-5 shows the definitions of the following signal states:

•

Active state, when a bus or signal is driven, and enters a low impedance state.

•

Tri-stated, when a bus or signal is placed in a high impedance state.

•

Data Valid state, when a signal level has reached VOL or VOH.

•

Data Invalid state, when a signal level is in transition between VOL and VOH.

Figure 4-5 Signal State

3.3V

Regulator

1.8V

Regulator

Supply

VDD

VDDIO, VDDA

VIH

VIL

Fall Time

Input Signal

Note: The midpoint is VIL + (VIH – VIL)/2.

Midpoint1

Low

High

90%

50%

10%

Rise Time

Data Invalid State

Data1

Data2 Valid

Data

Tri-stated

Data3 Valid

Data2

Data3

Data1 Valid

Data Active

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