![](http://datasheet.mmic.net.cn/370000/P9S12XEP100J1VVLR_datasheet_16728329/P9S12XEP100J1VVLR_948.png)
Appendix A Electrical Characteristics
MC9S12XE-Family Reference Manual , Rev. 1.07
948
Freescale Semiconductor
A.6
Reset, Oscillator and PLL
This section summarizes the electrical characteristics of the various startup scenarios for oscillator and
phase-locked loop (PLL).
A.6.1
Startup
Table A-22
summarizesseveralstartupcharacteristicsexplainedinthissection.Detaileddescriptionofthe
startup behavior can be found in the Clock and Reset Generator (CRG) block description
A.6.1.1
POR
The release level V
PORR
and the assert level V
PORA
are derived from the V
DD
supply. They are also valid
if the device is powered externally. After releasing the POR reset the oscillator and the clock quality check
are started. If after a time t
CQOUT
no valid oscillation is detected, the MCU will start using the internal self
clock. The fastest startup time possible is given by n
uposc
.
A.6.1.2
SRAM Data Retention
Provided an appropriate external reset signal is applied to the MCU, preventing the CPU from executing
codewhenV
DD35
isoutofspecificationlimits,theSRAMcontentsintegrityisguaranteedifafterthereset
the PORF bit in the CRG flags register has not been set.
A.6.1.3
External Reset
When external reset is asserted for a time greater than PW
RSTL
the CRG module generates an internal
reset, and the CPU starts fetching the reset vector without doing a clock quality check, if there was an
oscillation before reset.
A.6.1.4
Stop Recovery
Out of stop the controller can be woken up by an external interrupt. A clock quality check as after POR is
performed before releasing the clocks to the system.
If the MCU is woken-up by an interrupt and the fast wake-up feature is enabled (FSTWKP = 1 and
SCME = 1), the system will resume operation in self-clock mode after t
fws
.
Table A-22. Startup Characteristics
Conditions are shown in
Table A-4
unless otherwise noted
Num
C
Rating
Symbol
Min
Typ
Max
Unit
1
D Reset input pulse width, minimum input time
PW
RSTL
2
—
—
t
osc
2
D Startup from reset
n
RST
192
—
196
n
osc
3
D Wait recovery startup time
t
WRS
—
—
14
t
cyc
μ
s
4
D Fast wakeup from STOP
1
1
Including voltage regulator startup; V
DD
/V
DDF
filter capacitors 220 nF, V
DD35
= 5 V, T= 25
°
C
t
fws
—
50
100