3819 datasheet(60/218 Pages) RENESAS

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3819 Group

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS

RESET CIRCUIT

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

level for 2

µs or more. Then the RESET pin is returned to an “H”

level (the power source voltage should be between 2.8 V and 5.5

V, and XIN oscillation is stable), reset is released. In order to give

the XIN clock time to stabilize, internal operation does not begin

until after about 4000 XIN clock cycles (256 cycles of f(XIN)/16) are

completed. After the reset is completed, the program starts from

the address contained in address FFFD16 (high-order) and ad-

dress FFFC16 (low-order). Make sure that the reset input voltage

is 0.5 V or less for 2.8 V of VCC.

Fig. 44 Example of reset circuit

Fig. 45 Reset sequence

Note : Reset release voltage : VCC = 2.8 V

Power source

voltage

Poweron

(Note)

VCC

RESET

VCC

RESET

Power source voltage

detection circuit

0 V

Reset input

voltage

0.2VCC

0 V

about 4000

XIN clock cycles

RESET

Internal reset

f(XIN) and f(

φ) are in the relationship : f(XIN) = 8•f(φ)

A question mark (?) indicates an undefined state that depends on the previous state.

Notes 1 :

2 :

SYNC

Data

Address

XIN

Reset address from

vector table

FFFC

FFFD

ADH, ADL

ADL

ADH

3819 Datasheet(PDF) 60 Page - Renesas Technology Corp

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