
Electrical Specifications
Data Sheet
MC68HC908SR12MC68HC08SR12 — Rev. 5.0
378
Electrical Specifications
Freescale Semiconductor
24.10 5.0V Oscillator Characteristics
Figure 24-1. RC vs. Bus Frequency (5V @25
°
C)
Table 24-8. 5V Oscillator Specifications
Characteristic
Symbol
Min
Typ
Max
Unit
Internal oscillator clock frequency
f
ICLK
19.2k
24k
28.8k
Hz
External reference clock to OSC1
(1)
Notes
:
1. No more than 10% duty cycle deviation from 50%.
2. Fundamental mode crystals only.
3. Consult crystal manufacturer’s data.
4. Not Required for high frequency crystals.
f
OSC
dc
—
20M
Hz
Crystal reference frequency
(2)
f
XCLK
32.768k
4.9152M
Hz
Crystal load capacitance
(3)
C
L
—
—
—
Crystal fixed capacitance
C
1
—
2
×
C
L
(25p)
—
F
Crystal tuning capacitance
C
2
—
2
×
C
L
(25p)
—
F
Feedback bias resistor
R
B
—
10M
—
Series resistor
(4)
R
S
—
100k
—
External RC clock frequency
f
RCCLK
2M
—
18M
Hz
External resistor
R
EXT
See
Figure 24-1
External capacitor
C
EXT
—
10
—
pF
R
EXT
C
EXT
OSC1
V
DD
MCU
0
0
2
4
6
8
10
5
4
3
2
1
Resistor R
EXT
(k
)
B
O
C
EXT
= 10 pF
5V @ 25
°
C
f
RCCLK
= f
OP
×
4