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CHAPTER 5 CLOCK
5.5
Oscillation Stabilization Wait Interval
When the power is turned on, when stop mode is released, or when a watchdog timer
reset occurs, the oscillation clock starts, oscillation is unstable initially. Therefore, an
oscillation stabilization wait interval is required. When the switch from the main clock to
a PLL clock occurs, an oscillation stabilization wait interval is also required when PLL
oscillation starts.
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Oscillation Stabilization Wait Interval
Ceramic and crystal oscillators generally require an oscillation stabilization wait interval of a few to several
dozen milliseconds until they stabilize at their natural frequency when oscillation starts.
For this reason, CPU operation is not allowed as soon as oscillation starts and is allowed only after full
stabilization of oscillation. After the oscillation stabilization wait interval has elapsed, the clock is supplied
to the CPU.
Because the oscillation stabilization time depends on the type of the oscillator (crystal, ceramic, etc.), the
proper oscillation stabilization wait interval for the oscillator used must be selected. An oscillation
stabilization wait interval is selected by setting the clock selection register (CKSCR).
In a switch from the main clock to a PLL clock, the CPU continues to operate on the main clock during the
oscillation stabilization wait interval. After this interval, the operating clock switches to the PLL clock.
Figure 5.5-1 shows the operation after oscillation starts.
Figure 5.5-1 Operation when Oscillation Starts
Oscillator-activated Oscillation stabilization Normal operation start
Start of oscillation
Stable oscillation
oscillation time
wait interval
or change to PLL clock
Summary of Contents for MB90460 Series
Page 1: ...The following document contains information on Cypress products ...
Page 3: ......
Page 5: ......
Page 9: ...iv ...
Page 41: ...22 CHAPTER 1 OVERVIEW ...
Page 45: ...26 CHAPTER 2 NOTES ON HANDLING DEVICES ...
Page 83: ...64 CHAPTER 3 CPU ...
Page 95: ...76 CHAPTER 4 RESET ...
Page 107: ...88 CHAPTER 5 CLOCK ...
Page 131: ...112 CHAPTER 6 LOW POWER CONSUMPTION MODE ...
Page 175: ...156 CHAPTER 7 INTERRUPT ...
Page 181: ...162 CHAPTER 8 MODE SETTING ...
Page 223: ...204 CHAPTER 9 I O PORT ...
Page 237: ...218 CHAPTER 10 TIME BASE TIMER ...
Page 247: ...228 CHAPTER 11 WATCHDOG TIMER ...
Page 275: ...256 CHAPTER 12 16 BIT RELOAD TIMER ...
Page 373: ...354 CHAPTER 14 MULTI FUNCTIONAL TIMER ...
Page 485: ...466 CHAPTER 16 PWC Timer ...
Page 531: ...512 CHAPTER 17 UART ...
Page 559: ...540 CHAPTER 19 DELAYED INTERRUPT GENERATOR MODULE ...
Page 589: ...570 CHAPTER 20 8 10 BIT A D CONVERTER ...
Page 601: ...582 CHAPTER 21 ROM CORRECTION FUNCTION ...
Page 633: ...614 CHAPTER 23 512K 1024K BIT FLASH MEMORY ...
Page 645: ...626 CHAPTER 24 EXAMPLE OF F2 MC 16LX MB90F462 F462A F463A CONNECTION FOR SERIAL WRITING ...
Page 715: ...696 APPENDIX ...
Page 716: ...697 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
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