HD6473847RHV Datasheet, PDF (138/546 Pages) Renesas Technology Corp – Renesas 8-Bit Single-Chip Microcomputer H8 Family / H8/300L Super Low Power Series

Section 4 Clock Pulse Generators
4.6.3 Definition of Oscillation Stabilization Standby Time
Figure 4.16 shows the oscillation waveform (OSC2), system clock (φ), and microcomputer
operating mode when a transition is made from standby mode, watch mode, or subactive mode, to
active (high-speed/medium-speed) mode, with a resonator connected to the system clock
oscillator.
As shown in figure 4.16, as the system clock oscillator is halted in standby mode, watch mode,
and subactive mode, when a transition is made to active (high-speed/medium-speed) mode, the
sum of the following two times (oscillation stabilization time and standby time) is required.
1. Oscillation stabilization time (t_rc)
The time from the point at which the oscillation waveform of the system clock oscillator starts to
change when an interrupt is generated, until the amplitude of the oscillation waveform increases
and the oscillation frequency stabilizes.
2. Standby time
The time required for the CPU and peripheral functions to begin operating after the oscillation
waveform frequency and system clock have stabilized.
The standby time setting is selected with standby timer select bits 2 to 0 (STS2 to STS0) (bits 6 to
4 in the system control register 1 (SYSCR1)).
Rev. 7.00 Mar. 08, 2010 Page 106 of 510
REJ09B0024-0700