MMA955xL

Sensors

20

Freescale Semiconductor, Inc.

4.12

AC Electrical Characteristics

Tests are conducted using the input levels specified in Table 5 on page 17. Unless otherwise specified, propagation delays are

measured from the 50-percent to 50-percent point. Rise and fall times are measured between the 10-percent and 90-percent

points, as shown in the following figure.

Figure 10. Input signal measurement references

The subsequent figure shows the definitions of the following signal states:

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

• Three-stated, when a bus or signal is placed in a high-impedance state

Figure 11. Signal states

4.13

General Timing Control

1.

Characteristic

Symbol

Condition(s)

Min

Typ

Max

Unit

10% to 90%

1

ms

2.

Power-up

0.35

1.5

ms

Warm-up time

7

sample

periods

Frequency of operation

Full Speed Clock

8

MHz

Slow Clock

62.5

KHz

System clock period

Full Speed Clock

125

ns

Slow Clock

16

μs

Full/Slow clock ratio

128

Oscillator frequency absolute accuracy @ 25°C

Full Speed Clock

-5

+5

%

Oscillator frequency variation over temperature

(-40°C to 85°C vs. ambient)

Slow Clock

-6

+6

%

Minimum RESET assertion duration

3.

In the formulas, T = 1 system clock cycle. In full speed mode, T is nominally 125 ns. In slow speed mode, T is nominally 16

μs.

Fall Time

Input Signal

Midpoint1

Low

High

90%

50%

10%

Rise Time

Data Invalid State

Data1

Data

3-stated

Data3 Valid

Data2

Data3

Data1 Valid

Data Active

Data Active

Data1 Valid