REJ03D0784-0200 Rev.2.00 Jun 15, 2007

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M62021L/P/FP

System Reset IC with Switch for Memory Backup

REJ03D0784-0200

Rev.2.00

Jun 15, 2007

Description

The M62021 is a system IC that controls the memory backup function of microcomputer (internal RAM).

The IC outputs reset signals (RES/

RES) to a microcomputer at power-down and power failure. It also shifts the power

supply to RAM from main to backup, outputs a signal (

CS) that invokes standby mode, and alters RAM to backup

circuit mode.

The M62021 contains, in a single chip, power supply monitor and RAM backup functions needed for a microcomputer

system, so that the IC makes it possible to construct a system easily and with fewer components compared with a

conventional case that uses individual ICs and discrete components.

Features

• Built-in switch for selection between main power supply and backup power supply to RAM.

• Small difference between input and output voltage (I

• Detection voltage (power supply monitor voltage) 4.40 V ± 0.2 V

• Chip select signal output (CS)

• Two channels of reset outputs (RES/RES)

• Power on reset circuit built-in

• Delay time variable by an external capacitance connected to Ct pin

• Facilitates to form backup function with a few number of components

Application

• Power supply control systems for memory backup of microcomputer system and SRAM boards with built-in backup

function that require switching between external power supply and battery.

Block Diagram

3

1

7

RES

5

RES

4 Ct

8

CS

–

+

1.24V

Com

SW

Reset

circuit

Delay

circuit

6

GND