MITSUMI PST621

System Reset (with battery back-up) PST620, 621
MITSUMI
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
Package
DIP-8B (PST620DDB, PST621DDB)
SOP-8C (PST620DFT, PST621DFT)
Applications
1.
2.
3.
4.
VCR
Audio equipment
Communications equipment
Rice cookers, etc.
Pin Assignment
8
7
6
5
1
2
3
4
Pin Description
PST620
Pin No.
Pin name
1
VAC
2
3
VCC1
VCC2
4
TC
5
6
7
8
RE
PSCONT
CE
GND
Function
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
System Reset (with battery back-up) PST620, 621
MITSUMI
PST621
Pin No.
Pin name
1
VAC
2
3
VCC1
VCC2
4
TC
--------------------------------
5
RE
6
MODE
7
8
CE
GND
Function
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
Switches 1-chip microcomputer mode with pulse
shaver output signal
Chip enable signal output (power outage detection signal)
GND
Block Diagram
PST621
PST620
Absolute Maximum Ratings
(Ta=25°C)
Item
Symbol
Rating
Storage temperature
TSTG
-40~+125°C
Operating temperature
TOPR
-20~+70°C
Power supply voltage
VCC max.
-0.3~+10V
TC input input voltage
VC max.
VCC1+0.3V
Allowable loss
Pd
450mW
System Reset (with battery back-up) PST620, 621
MITSUMI
Electrical Characteristics
Item
Detection voltage 1
Detection
PST620
voltage 2
PST621
Detection voltage 3
Hysteresis voltage 1
Hysteresis voltage 2
Hysteresis voltage 3
Detection voltage
temperature coefficient 1
Detection voltage
temperature coefficient 2
Detection voltage
temperature coefficient 3
Low-level output voltage 1
Low-level output voltage 2
(Ta=25°C)
Symbol
V S1
V S3
VS1
VS2
VS3
Measurement conditions
RL1=47kΩ CE output, VCC1=L H
1
RL2=47kΩ, RE output
VCC2=H L
1
RL1=47kΩ, CE output, VAC=H L
1
RL1=47kΩ, CE output, VCC1=L H L
RL2=47kΩ, CE output, VCC2=L H L
RL1=47kΩCE output, VAC=L H L
VS/ T
RL1=47kΩ, CE output
±0.01
VS/ T
RL2=47kΩ, RE output
±0.02
VS/ T
RL1=47kΩ, CE output
±0.01
VOL1
VOL2
VCC1=VS1 min.-0.05V, RL1=47kΩ CE output
VCC2=VS2 min.-0.05V, RL2=47kzΩ RE output
VCC1=0V, VCC2=VS2 typ./0.85
RL1=47kΩ, CE output
RL1=47kΩ, VOL1 <= 0.4V CE output
RL2=47kΩ, VOL2 <= 0.4V RE output
VCC1=VCC2=VS1/0.85
RL1=RL2=∞
VCC1=VCC2=VS1 min.-0.05V
RL1=RL2=∞
VCC1=VCC2=VS2 min.-0.05V
RL1=RL2=∞
VCC1=0V RL1=RL2=∞,
VCC2=VS1T typ./0.85
VCC1=0V RL1=RL2=∞
VCC2=VS2 min.-0.05V
VCC1=VS1 min.-0.05V, RL1=0 CE output
VCC2=VS2 min.-0.05V, RL2=0 RE output
VCC1=VS1 typ.±0.4V, RL2=47kΩ CE output
VCC2=VS2 typ.±0.4V, RL2=47kΩ RE output
VCC1=VS1 typ.±0.4V, RL2=47kΩ CE output
VCC2=VS2 typ.±0.4V, RL2=47kΩ RE output
0.1
0.1
0.2
0.4
0.2
0.4
0.8
0.8
5.0
2.0
8.0
2.0
8.0
4.0
1.0
1.0
8.5
3.5
14.5
3.5
14.5
7.0
2.0
3.5
4.0
7.0
V S2
Low-level output voltage 3
VOL3
Operation limit voltage 1
Operation limit voltage 2
VOP1
VOP2
ICC1
ICC2
ICC1
ICC2
ICC1
ICC2
Consumption current 1
Consumption current 2
Consumption current 3
Consumption current 4
ICC2
Consumption current 5
ICC2
Output current while on 1
Output current while on 2
Transport delay time 1
Transport delay time 2
Transport delay time 3
Transport delay time 4
AC pin input resistance
One-shot pulse width
One-shot output voltage
TC pin threshold voltage
TC input input current
PS pin input H level voltage
PS pin input L level voltage
PS pin input H level current
IOL1
IOL2
TPLH1
TPLH2
TPLH3
TPLH4
RACIN
Tpd
VTOL
VCTH
ICIN
VPSH
VPSL
IPSH
*
*
Cd=0.47µF Rd=100k, VCC1=VS1 typ.±0.4V
VCC1=VS1 typ./0.85, RL1=47kΩ RE output, 1
RL1=47kΩ, VC=L H
VCC1=VS1 typ./0.85, VC=5.0V
Typ.
4.20
2.15
3.10
2.00
150
50
90
Max. Units
4.40
2.30
V
3.30
2.15
300
100 mV
180
%/°C
2
2
V
µA
0.5
6
mA
10
50
40
80
1.0
14
0.1
2.0
µS
21
0.4
1
2.0
VPSH=2.0V
V
µA
*
Note 1 : 1 Connect TC pin to GND.
Note 2 : Except where noted otherwise, VAC=5V, Vc=OPEN.
*
*
Min.
4.00
2.00
2.90
1.85
75
25
45
0.6
10
MΩ
mS
V
V
µA
V
V
µA
System Reset (with battery back-up) PST620, 621
MITSUMI
Characteristics
(PST620, 621 series. However, VS2 in PST620 series only.)
Current consumption
VS1
ICC1
(µA)
15.00
ICC1
(µA)
15.00
1.500/div
1.500/div
.0000
.0000
1.000/div
(V)
4.400
.4400/div
.4400/div
.0000
.0000
.0000
10.00
VCC1(V)
VS2
.0900/div
.2300/div
.0000
2.100
1 shot pulse width-Temperature
.0000
.0000
Vs1 detection
voltage (V)
5
-25
0
25
50
1.000/div
4.30
4.20
4.10
75
-25
Temperature (°C)
0
25
50
75
Temperature (°C)
Vs2 detection voltage-Temperature
Vs3 detection voltage-Temperature
2.10
Vs3 detection
voltage (V)
2.20
2.10
2.00
.0000
10.00
VCC1 (V)
Vs1 detection voltage-Temperature
10
0
1.000/div
1.000/div
.0000
2.300
VCC1 (V)
.0200/div
REST
(V)
10.00
CS
(V)
10.00
(V)
2.300
.2300/div
Vs2 detection
voltage (V)
.0000
10.00
VCC1 (V)
VOL
(V)
2.300
Pulse width (mS)
(V)
4.400
2.00
1.90
-25
0
25
50
Temperature (°C)
75
-25
0
25
50
Temperature (°C)
75
System Reset (with battery back-up) PST620, 621
MITSUMI
Timing Chart
PST620
4.2V
VCC1
2.15V
VCC2
CE
TC
Delay
Delay
RE
Note : Connect VAC pin to VCC when not using.
AC power supply
AC rectifier or
regulator
primary side
VTX
CE
Note 1: VTH is set at 2.0V and hysteresis voltage at 90mV.
1. Use a resistor to divide the detected voltage so that it equals VTH when monitoring regulator
primary side power supply.
2. When monitoring AC voltage rectified as in the application circuit, set so that it equals VTH by
lowering the constant and dividing with a resistor. Refer to application circuit diagram.
Note 2: VAC input and VS1 are OR, so either signal makes CE low when power outage is detected.
PST621
AC
VCC1
4.2V
CE
MODE
VCC2
3.1V
RESET
Application Circuits
VAC input : Power supply transformer secondary voltage detection
System Reset (with battery back-up) PST620, 621
MITSUMI
1. Connection
1. +5V power supply to VCC1 (Pin 2).
2. Connect back-up capacitor to VCC2 (Pin 3).
3. Connect a diode between VCC1 (Pin 2) and VCC2 (Pin 3).
4. Connect pulse width setting resistor and capacitor to PC (Pin 4) when using pulse shaver.
5. RE output (Pin 5) is reset signal output and is output when VCC is less than 2.15V.
6. When using pulse shaver, PSCONT (Pin 6) is high level.
7. CE output (Pin 7) is for chip enable signal and goes low when power outage is detected.
2. Theory of Operation
1. When +5V power is supplied normally, it is charged to the back-up capacitor via a diode.
2. The back-up capacitor starts back-up if +5V power supply voltage drops for some reason and
VCC1 goes below 4.2V, and at the same time the CE signal switches the 1-chip microcomputer to
standby mode, so that it operates on low current consumption.
3. When +5V power supply recovers and goes over 4.2V, an RE output signal of a certain width is
output, and this signal resets the 1-chip microcomputer. At the same time normal mode starts and
the time until crystal oscillator output stabilizes is reset.
4. If +5V power supply does not recover, and back-up capacitor voltage goes below 2.15V, reset is
carried out by the RE output signal to prevent the microcomputer from running wild.
3. Setting AC power supply power outage detection
1. Theory of operation for detecting AC voltage
AC voltage is rectified and smoothed by the capacitor. This voltage is divided and set at VAC input
detection voltage, +2V. At this time the smoothing capacitor and dividing resistor time constants
are used to set AC voltage missing waveform.
2. VAC voltage setting (R1, R2)
Set resistor ratio at the midpoint between R1 and R2 so that the voltage to be detected is +2V.
Impressed AC voltage
There is are no limitations on AC voltage as it is divided by R1 and R2 and applied to PST620.
3. Setting time constants to detect AC voltage (C4, R1+R2)
For impressed AC voltage of 5Vrms, and C4 and R1+R2 time constant of 60mS, set so that AC
voltage detects power outage when approximately 2 waveforms are missed. The time constants
can be set to detect missing AC waveforms.
--------------------------
Application Circuits
VAC input : Stable power supply primary voltage detection