MC9S12DP256B Datasheet, PDF (106/126 Pages) Freescale Semiconductor, Inc – device made up of standard HCS12 blocks and the HCS12 processor core

MC9S12DP256B Device User G^Fui^rd^ee^e—^scV0^a2.^l1^e5 ^{Semiconductor, Inc.}
A.5.1.4 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.
A.5.1.5 Pseudo Stop and Wait Recovery
The recovery from Pseudo STOP and Wait are essentially the same since the oscillator was not stopped in
both modes. The controller can be woken up by internal or external interrupts. After t_wrs the CPU starts
fetching the interrupt vector.
A.5.2 Oscillator
The device features an internal Colpitts oscillator. By asserting the XCLKS input during reset this
oscillator can be bypassed allowing the input of a square wave. Before asserting the oscillator to the
internal system clocks the quality of the oscillation is checked for each start from either power-on, STOP
or oscillator fail. t_CQOUT 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 t_UPOSC. The device also features a clock monitor. A Clock Monitor Failure is
asserted if the frequency of the incoming clock signal is below the Assert Frequency f_CMFA.
Table A-15 Oscillator Characteristics
Conditions are shown in Table A-4 unless otherwise noted
Num C
Rating
Symbol Min
1 C Crystal oscillator range
f_OSC
0.5
2 P Startup Current
i_OSC
100
3 C Oscillator start-up time
t_UPOSC
4 D Clock Quality check time-out
t_CQOUT
0.45
5 P Clock Monitor Failure Assert Frequency
f_CMFA
50
6 P _{External square wave input frequency}³
f_EXT
0.5
7 D External square wave pulse width low
t_EXTL
9.5
8 D External square wave pulse width high
t_EXTH
9.5
9 D External square wave rise time
t_EXTR
10 D External square wave fall time
t_EXTF
11 D Input Capacitance (EXTAL, XTAL pins)
C_IN
12
C
DC Operating Bias in Colpitts Configuration on
EXTAL Pin
V_DCBIAS
NOTES:
1. f_osc = 4MHz, C = 22pF.
2. Maximum value is for extreme cases using high Q, low frequency crystals
3. XCLKS =0 during reset
Typ
8¹
100
9
1.1
Max
16
100²
2.5
200
50
1
1
Unit
MHz
µA
ms
s
KHz
MHz
ns
ns
ns
ns
pF
V
108
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