Oscillator
Various oscillator options offer the user a wide range of functions according to their various applica-
tion requirements. Two types of system clocks can be selected while various clock source options
for the Watchdog Timer are provided for maximum flexibility. All oscillator options are selected
through the configuration options.
System Clock Configurations
There are two methods of generating the system clock, using an external crystal/ceramic oscilla-
tor or an external RC network. The chosen method is selected through the configuration options.
System Crystal/Ceramic Oscillator
For the crystal oscillator configuration, the simple connection of a crystal across OSC1 and OSC2
will create the necessary phase shift and feedback for oscillation with no other external compo-
nents required. A ceramic resonator can be used instead of a crystal but two small value capaci-
tors should be connected between OSC1, OSC2 and ground.
The table below shows the C1, C2 and R1 values for various crystal/ceramic oscillating frequen-
cies.
Crystal or Resonator
C1, C2
R1
4MHz Crystal
0pF
10k
W
4MHz Resonator
10pF
12k
W
3.58MHz Crystal
0pF
10k
W
3.58MHz Resonator
25pF
10k
W
2MHz Crystal & Resonator
25pF
10k
W
1MHz Crystal
35pF
27k
W
480kHz Resonator
300pF
9.1k
W
455kHz Resonator
300pF
10k
W
429kHz Resonator
300pF
10k
W
The function of the resistor R1 is to ensure that the oscillator will switch off should low voltage
conditions occur. Such a low voltage, as mentioned here, is one which is less than the lowest
value of the MCU operating voltage. Note however that if the LVR is enabled then R1 can be re-
moved.
72
A/D Type MCU
O S C 2
O S C 1
C 2
C 1
R 1
Crystal/Ceramic Oscillator
Содержание HT46R22
Страница 7: ...vi A D Type MCU...
Страница 9: ...viii A D Type MCU...
Страница 10: ...P a r t I Microcontroller Profile Part I Microcontroller Profile 1...
Страница 11: ...2 A D Type MCU...
Страница 90: ...P a r t I I Programming Language Part II Programming Language 81...
Страница 91: ...82 A D Type MCU...
Страница 97: ...88 A D Type MCU...
Страница 128: ...P a r t I I I Development Tools Part III Development Tools 119...
Страница 129: ...120 A D Type MCU...
Страница 140: ...Appendix Appendix 131...
Страница 141: ...132 A D Type MCU...
Страница 151: ...142 A D Type MCU...
Страница 152: ...A p p e n d i x B Package Information Appendix B Package Information 143 B...
Страница 161: ...A D Type MCU...
Страница 162: ...Amendments...