7477 datasheet(180/354 Pages) RENESAS

180 / 354 page

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7470/7471/7477/7478 GROUP USER’S MANUAL

HARDWARE

1.17 Low-power dissipation function

Fig. 1.17.3 oscillation stabilizing wait time at recovery from stop mode by reset input

(2) Releasion of stop mode

The stop mode is released by inputting a reset signal or generating an interrupt request. There is a

difference in restore processing from the stop mode between the use of reset input and the use of

interrupt.

2 Recovery by reset input

____________________

The microcomputer is reset by applying the "L" level to the RESET pin for 2

s or more in the stop

mode, thereby releasing the stop mode.

After the stop mode is released, oscillator starts. (At this time, the inside is in the reset state.)

The reset state is released after 32768 counts of the X IN pin input after the “H” level is applied to

the RESET pin.

At a start of oscillation of the oscillator, the oscillation is unstable. It takes time before stabilization

of oscillation (oscillation stabilizing time). The oscillation stabilizing wait time is secured by the time

for holding this internal reset state.

For the details of the reset, Refer to “1.15 Reset.”

Note: When the stop mode is released, the contents of the RAM before reset are held. However,

the contents of the CPU register and the SFR cannot be held but are reset.

Figure 1.17.3 shows the oscillation stabilizing wait time at recovery from stop mode by reset input.

RESET

XIN

VCC

Execute STP instruction

Recovered by reset input

Stop mode

µs or more

(Note)

Note: No waveform may be input to X

(in low-speed mode).

Undefined

XIN: in high-impedance state

XOUT: “H”

Oscillation stabilizing wait time : 32768 counts of X IN pin input signal

7477 Datasheet(PDF) 180 Page - Renesas Technology Corp