M38506MB-FP View Datasheet(PDF) - Renesas Electronics

Part Name

Description

MFG CO.

M38506MB-FP

8-BIT CISC SINGLE-CHIP MICROCOMPUTER

Renesas Electronics 

HARDWARE

FUNCTIONAL DESCRIPTION

RESET CIRCUIT

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

level for 20 cycles or more of XIN. Then the RESET pin is returned

to an “H” level (the power source voltage must be between 2.7 V

and 5.5 V, and the oscillation must be stable), reset 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 input voltage is

less than 0.54 V for VCC of 2.7 V.

RESET

Power source

VCC voltage

0V

Reset input

voltage

0V

Poweron

(Note)

0.2VCC

Note : Reset release voltage; Vcc = 2.7 V

RESET

VCC

Power source

voltage detection

circuit

Fig. 36 Reset circuit example

XIN

φ

RESET

RESETOUT

Address

Data

SYNC

?

?

?

?

FFFC FFFD ADH,L

Reset address from the vector table.

?

?

?

?

ADL

ADH

XIN: 8 to 13 clock cycles

Notes 1: The frequency relation of f(XIN) and f(φ) is f(XIN) = 2 • f(φ).

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

3: All signals except XIN and RESET are internals.

Fig. 37 Reset sequence

1-34

3850 Group (Spec. H) User’s Manual

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