MB89960 series
CHAPTER 3 CPU
57
3
3.6 Clocks
3.6.2 Osc. Stabilization Delay, Regulator Stabilization Time and
Regulator Recovery Time
This section describe the oscillation stabilization delay time, the regulator stabilization
time and the regulator recovery time.
s Oscillation Stabilization Delay Time
After starting, ceramic, crystal, and other oscillators typically require the time between several
milliseconds and several tens of milliseconds to stabilize at their fixed oscillation frequency.
Therefore, operation of the CPU and other functions is disabled when oscillation first starts and
no clock signal is supplied to the CPU and peripheral functions until the oscillation stabilization
delay time has passed and the oscillation has sufficiently stabilized.
The time required for oscillation to stabilize depends on the oscillator type (crystal, ceramic,
etc.) connected to the clock generator. Consequently, it is necessary to select an oscillation
stabilization delay time that matches the type of oscillator being used.
The oscillation stabilization delay time can be selected as an option by specifying a bit in the
counter of the time-based timer as the oscillation stabilization delay time bit. The oscillation
stabilization delay time is the time from when the counter starts counting up from zero until an
overflow occurs on the specified bit.
The MB89960 series require a delay for oscillation to stabilize after a power-on reset, after an
external reset in stop mode, or when an external interrupt triggers recovery from stop mode.
Figure 3.6.1 shows the operation of an oscillator after starting oscillation.
Figure 3.6.2a Operation of an Oscillator after Starting Oscillation
s Regulator Recovery Time
MB89965 contain an on-chip voltage regulator for the internal 3V circuits. In power-down mode
or in the stop mode, the internal voltage regulator is turned off to minimize power consumption.
The Regulator Recovery Time is the the time for the internal voltage regulator to resume normal
operation.
The Regulator Recovery Time is 20u second long, and it is required only in MB89965.
s Regulator Stabilization Time
When power-on, the on-chip voltage regulator requires a stabilization time in additional to the
oscillation stabilization time. This additional wait time is call Regulator Stabilization Time. The
external power supply voltage must reach the mininum operation voltage within the Regulator
stabilization time.
Oscillator oscillation time
Oscillation stabilization delay time
Normal operation
(recovery from stop
mode or reset operation)
Oscillation starts
Oscillation stabilizes