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MITSUMI
System Reset (with battery back-up) PST620, 621
System Reset (with battery back-up)
Monolithic IC PST620, 621
Outline
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.
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
PST620
1
4
3
2
8
5
6
7
Pin No.
Pin name
Function
1
V
AC
Has +2.0V detection voltage to detect AC power supply and
stable power supply primary side, for quick power outage detection.
+5V main power supply
Back-up power supply (back-up capacitor connected)
Pulse width setting pin for pulse shaver
(capacitor and resistor connected)
Reset output
Pulse shaver ON/OFF switching High : OFF Low : ON
Chip enable signal output
GND
2
3
V
CC1
V
CC2
4
TC
5
6
7
8
RE
PS
CONT
CE
GND
Package
DIP-8B (PST620DDB, PST621DDB)
SOP-8C (PST620DFT, PST621DFT)