TMP86FS49FG datasheet(21/42 Pages) TOSHIBA

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Page 19

TMP86FS49FG

Figure 2-8 Edge-sensitive Release Mode

STOP mode is released by the following sequence.

1. In the dual-clock mode, when returning to NORMAL2, both the high-frequency and low-

frequency clock oscillators are turned on; when returning to SLOW1 mode, only the low-

frequency clock oscillator is turned on. In the single-clock mode, only the high-frequency

clock oscillator is turned on.

2. A warm-up period is inserted to allow oscillation time to stabilize. During warm up, all

internal operations remain halted. Four different warm-up times can be selected with the

WUT (Bits 2 and 3 in SYSCR1) in accordance with the resonator characteristics.

3. When the warm-up time has elapsed, normal operation resumes with the instruction follow-

ing the STOP mode start instruction. The start is made after the prescaler and the divider of

the timing generator are cleared to “0”.

Note: The warm-up time is obtained by dividing the basic clock by the divider. Therefore, the warm-up

time may include a certain amount of error if there is any fluctuation of the oscillation frequency

when STOP mode is released. Thus, the warm-up time must be considered as an approximate

value.

STOP mode can also be released by inputting low level on the RESET pin, which immediately per-

forms the normal reset operation.

Note: When STOP mode is released with a low hold voltage, the following cautions must be observed.

The power supply voltage must be at the operating voltage level before releasing STOP mode.

The RESET pin input must also be “H” level, rising together with the power supply voltage. In this

case, if an external time constant circuit has been connected, the RESET pin input voltage will

increase at a slower pace than the power supply voltage. At this time, there is a danger that a

reset may occur if input voltage level of the RESET pin drops below the non-inverting high-level

input voltage (Hysteresis input).

Table 2-1 Warm-up Time Example (at fc = 16.0 MHz, fs = 32.768 kHz)

WUT

Warm-up Time [ms]

Return to NORMAL Mode

Return to SLOW Mode

12.288

750

4.096

250

3.072

5.85

1.024

1.95

NORMAL

operation

NORMAL

operation

VIH

STOP mode is released by the hardware at the rising

edge of STOP pin input.

Warm up

STOP mode started

by the program.

STOP

operation

STOP

operation

STOP pin

XOUT pin

TENTATIVE

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