MC68HC908GT16_07 FREESCALE [Freescale Semiconductor, Inc], MC68HC908GT16_07 Datasheet - Page 261

• Manufacturer Part Number: MC68HC908GT16_07
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

20.10 Internal Oscillator Characteristics
20.11 External Oscillator Characteristics
Freescale Semiconductor
Internal oscillator base frequency
Internal oscillator tolerance
Internal oscillator multiplier
External clock option
External crystal options
Crystal load capacitance
Crystal fixed capacitance
Crystal tuning capacitance
Feedback bias resistor
Series resistor
1. V
2. Internal oscillator is selectable through software for a maximum frequency. Actual frequency will be
3. f
4. Multiplier must be chosen to limit the maximum bus frequency of 4 MHz for 2.7-V operation and 8 MHz
10. Not required for high-frequency crystals
1. V
2. Setting EXTCLKEN configuration option enables OSC1 pin for external clock square-wave input.
3. No more than 10% duty cycle deviation from 50%
4. EXTSLOW configuration option configures external oscillator for a slow speed crystal and sets the clock monitor circuits of
5. Some modules may require a minimum frequency greater than dc for proper operation. See appropriate table for this
6. MCU speed derates from 32 MHz at V
7. Setting EXTCLKEN and EXTXTALEN configuration options enables OSC1 and OSC2 pins for external crystal option.
8. f
9. Consult crystal vendor data sheet, see
With ICG clock disabled
With ICG clock enabled
EXTSLOW = 1
EXTSLOW = 0
multiplier (N) x base frequency.
for 4.5-V operation.
Bus
EXTSLOW = 1
EXTSLOW = 0
the ICG module to expect an external clock frequency that is higher/lower than the internal oscillator base frequency,
f
information.
DD
Bus
INTOSC.
DD
= (f
= 5.5 Vdc to 2.7 Vdc, V
= (f
= 5.5 to 2.7 Vdc, V
INTOSC
EXTOSC
(9)(10)
(4)
(4)
/ 4) x N when internal clock source selected
(4)
(4)
Characteristic
Characteristic
/ 4) when external clock source is selected.
(2)(3)
MC68HC908GT16 • MC68HC908GT8 • MC68HC08GT16 Data Sheet, Rev. 5.0
(9)
(7)(8)
(9)
(9)
(9)
(4)
SS
= 0 Vdc, T
SS
(2), (3)
= 0 Vdc, T
(1)
(1)
A
DD
= T
Figure 7-4. External Clock Generator Block
A
= 4.5 Vdc to 16 MHz at V
A
= T
(min) to T
A
(min) to T
A
(max), unless otherwise noted
A
f
Symbol
Symbol
f
f
OSC_TOL
f
(max), unless otherwise noted
EXTOSC
EXTOSC
INTOSC
C
C
C
R
R
N
L
1
2
B
S
DD
= 2.7 Vdc.
307.2 k
230.4
dc
30 k
Min
Min
–25
1 M
60
—
—
—
—
—
1
(5)
Diagram.
Internal Oscillator Characteristics
2 x C
2 x C
307.2
Typ
Typ
10
—
—
—
—
—
—
—
—
—
L
L
32 M
307.2 k
32 M
100 k
10 M
Max
Max
384
+25
127
—
—
—
—
—
(6)
(6)
Unit
Unit
kHz
MΩ
MΩ
Hz
Hz
pF
pF
pF
—
%
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