38K2 datasheet(113/358 Pages) RENESAS

113 / 358 page

FUNCTIONAL DESCRIPTION

Rev.2.00

Oct 15, 2006

page 94 of 130

38K2 Group

REJ09B0338-0200

HARDWARE

Fig. 137 Example of reset circuit

RESET CIRCUIT

To reset the microcomputer, RESET pin should be held at an “L”

level for 16 cycles or more of XIN. Then the RESET pin is returned

to an “H” level (the power source voltage should be between 3.0 V

and 5.25 V for L version, and the oscillation should be stable), re-

set is released. After the reset is completed, the program starts

from the address contained in address FFFD16 (high-order byte)

and address FFFC16 (low-order byte). Make sure that the reset in-

put voltage is under 0.6 V for VCC of 3.0 V (L version).

Fig. 138 Reset sequence

0 V

VCC

RESET

VCC

RESET

(Note)

0.2VCC

Poweron

Power

source

voltage

Reset input

voltage

Note : Reset release voltage ;

Vcc = 3.0 V (L version)

Power source

voltage detection

circuit

RESET

Internal

reset

Data

Address

SYNC

XIN: 10.5 to 18.5 clock cycles

XIN

FFFC

FFFD

ADH,L

ADL

ADH

1: The frequency relation of f(XIN) and f(

φ) is f(XIN)=8 • f(φ).

2: The question marks (?) indicate an undefined state that depends on the previous state.

Reset address from the vector table.

Notes

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