MC9S12E Motorola, MC9S12E Datasheet - Page 123

• Manufacturer Part Number: MC9S12E
• Description: MC9S12E-Family Device User Guide V01.04
• Manufacturer: Motorola

B.4.2 Oscillator
The device features an internal Colpitts and Pierce oscillator. The selection of Colpitts oscillator or Pierce
oscillator/external clock depends on the XCLKS signal which is sampled during reset. Pierce
oscillator/external clock mode allows 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
POR or STOP if a proper oscillation is not detected. The quality check also determines the minimum
oscillator start-up time t
asserted if the frequency of the incoming clock signal is below the Assert Frequency f
Conditions are shown in Table A-4 unless otherwise noted
Num C
NOTES:
1. Depending on the crystal a damping series resistor might be necessary
2. f
3. Maximum value is for extreme cases using high Q, low frequency crystals
4. Only valid if Pierce oscillator/external clock mode is selected
1a
1b
10
11
12
13
14
15
2
3
4
5
6
7
8
9
osc
C Crystal oscillator range (Colpitts)
C Crystal oscillator range (Pierce)
P Startup Current
C Oscillator start-up time (Colpitts)
D Clock Quality check time-out
P Clock Monitor Failure Assert Frequency
P External square wave input frequency
D External square wave pulse width low
D External square wave pulse width high
D External square wave rise time
D External square wave fall time
D Input Capacitance (EXTAL, XTAL pins)
C
P EXTAL Pin Input High Voltage
P EXTAL Pin Input Low Voltage
C EXTAL Pin Input Hysteresis
= 4MHz, C = 22pF.
T EXTAL Pin Input High Voltage
T EXTAL Pin Input Low Voltage
DC Operating Bias in Colpitts Configuration on
EXTAL Pin
CQOUT
UPOSC
specifies the maximum time before switching to the internal self clock mode after
Rating
Freescale Semiconductor, Inc.
. The device also features a clock monitor. A Clock Monitor Failure is
Table B-3 Oscillator Characteristics
For More Information On This Product,
(4)
(4)
(4)
(4)
(4)
(4)
(4)
1
Go to: www.freescale.com
(4)
4
(4)
V
V
V
Symbol
V
V
V
HYS,EXTAL
t
t
IH,EXTAL
IH,EXTAL
CQOUT
IL,EXTAL
IL,EXTAL
UPOSC
f
t
t
t
t
DCBIAS
f
f
i
CMFA
f
EXTH
EXTR
EXTL
EXTF
C
OSC
OSC
OSC
EXT
IN
Device User Guide — 9S12E128DGV1/D V01.04
V
0.7*V
SSPLL
Min
0.45
100
0.5
0.5
0.5
9.5
9.5
50
DDPLL
- 0.3
Typ
100
250
1.1
8
7
2
V
CMFA.
0.3*V
DDPLL
Max
100
200
2.5
16
40
50
1
1
DDPLL
3
+ 0.3
Unit
MHz
MHz
MHz
KHz
mV
ms
µA
pF
ns
ns
ns
ns
V
V
V
V
V
s
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