Freescale Semiconductor, Inc.
Electrical Characteristics
3.8 Clock and Reset Generator Electrical
Characteristics
This section describes the electrical characteristics for the oscillator, phase-locked loop, clock monitor and
reset generator.
3.8.1 Oscillator Characteristics
The MAC7100 Family features an internal low power loop controlled Pierce oscillator and a full swing Pierce
oscillator/external clock mode. The selection of loop controlled Pierce oscillator or full swing Pierce
oscillator/external clock depends on the level of the XCLKS signal at the rising edge of the RESET signal.
Before asserting the oscillator to the internal system clock distribution subsystem, the quality of the
oscillation is checked for each start from either power on, STOP or oscillator fail. tCQOUT specifies the
maximum time before switching to the internal self clock mode after POR or STOP if a proper oscillation is
not detected. The quality check also determines the minimum oscillator start-up time tUPOSC. The device also
features a clock monitor. A Clock Monitor Failure is asserted if the frequency of the incoming clock signal
is below the Clock Monitor Assert Frequency fCMFA.
Table 17. Oscillator Characteristics
Num C
Rating
Symbol
Min
H1a C Crystal oscillator range (loop controlled Pierce)
fOSC
4.0
H1b C Crystal oscillator range (full swing Pierce) 1, 2
fOSC
0.5
H2 P Startup Current
IOSC
100
H3 C Oscillator start-up time (loop controlled Pierce)
tUPOSC
—
H4 D Clock Quality check time-out
tCQOUT
0.45
H5 P Clock Monitor Failure Assert Frequency
H6 P External square wave input frequency 2
fCMFA
50
fEXT
0.5
H7 D External square wave pulse width low
tEXTL
9.5
H8 D External square wave pulse width high
tEXTH
9.5
H9 D External square wave rise time
tEXTR
—
H10 D External square wave fall time
tEXTF
—
H11 D Input Capacitance (EXTAL, XTAL pins)
CIN
—
H12 C EXTAL pin DC Operating Bias in loop controlled VDCBIAS
—
mode
1 Depending on the crystal; a damping series resistor might be necessary
2 XCLKS negated during reset
3 fosc = 4 MHz, C = 22 pF.
4 Maximum value is for extreme cases using high Q, low frequency crystals
Typ
—
—
—
TBD 3
—
100
—
—
—
—
—
7
TBD
Max
Unit
16
MHz
40
MHz
—
µA
50 4
ms
2.5
s
200
KHz
40
MHz
—
ns
—
ns
1
ns
1
ns
—
pF
—
V
14
MAC7100 Microcontroller Family Hardware Specifications
MOTOROLA
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
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