MITSUMI

System Reset (with battery back-up) PST620, 621

System Reset (with battery back-up)

Monolithic IC PST620, 621

Outline

Features

1. Low current consumption

2. Capacitors (super capacitor, large capacity chemical capacitor) are used for back-up power supply, lowering

system cost

3. Stable 1-chip microcomputer crystal oscillator rise time maintained with the built-in pulse shaver.

4. In addition to power outage detection for main power supply (+5V), there are built-in pins to detect AC power

supply and +5V power supply primary side

5. Reset signal output by back-up power supply (super capacitor, large capacity chemical capacitor) detection

Applications

1. VCR

2. Audio equipment

3. Communications equipment

4. Rice cookers, etc.

Pin Assignment

Pin Description

14

3

2

85

6

7

PST620

Pin No.

Pin name

Function

1

Has +2.0V detection voltage to detect AC power supply and

stable power supply primary side, for quick power outage detection.

2

+5V main power supply

3

Back-up power supply (back-up capacitor connected)

4

TC

Pulse width setting pin for pulse shaver

(capacitor and resistor connected)

5

RE

Reset output

6

Pulse shaver ON/OFF switching High : OFF Low : ON

7

CE

Chip enable signal output

8

GND

GND

Package

DIP-8B (PST620DDB, PST621DDB)

SOP-8C (PST620DFT, PST621DFT)

These ICs are part of the regular series of back-up ICs, and use capacitors (super capacitor, large capacity

chemical capacitor) as back-up power supply. They control 1-chip microcomputer high-speed, low-speed,

and stand-by modes (MNI control).

These ICs also are capable of controlling data save in EPROM and other nonvolatile memories during power outage.