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
VAC
Has +2.0V detection voltage to detect AC power supply and
stable power supply primary side, for quick power outage detection.
2
VCC1
+5V main power supply
3
VCC2
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
PSCONT
Pulse shaver ON/OFF switching High : OFF Low : ON
7
CE
Chip enable signal output
8
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.
Products
to
be
discontinued