MITSUMI
System Reset PST993, 994
System Reset
Monolithic IC PST993, 994
Outline
The function of this IC is to accurately reset systems after detecting the supply voltage at the time of
switching power on and instantaneous power off in various CPU and other logic systems. Further, this IC can
be offered at low cost because it is designed to be simplified allowing for the replacement from reset circuit of
discrete configuration.
Features
1. Voltage detect precision
2. Low consumption current
3. Low operating threshold voltage
4. Hysteresis voltage is provided as detect voltage
5. Large output current at the time ON
6. Detect voltage rank
V
S
±5% max.
I
CCH
=300µA typ. I
CCL
=250µA typ.
0.65V typ.
50mV typ.
15mA typ.
PST993 C : 4.5V
H : 3.1V
D : 4.2V
I : 2.9V
E : 3.9V
J : 2.7V
F : 3.6V
K : 2.5V
G : 3.3V
L : 2.3V
(Same ranks for PST994 too)
7. Output form
PST993 : Constant current load built-in
PST994 : Open collector
Packages
TO-92A (PST993 , PST994 )
contains detection voltage rank.
*
Applications
1. Reset circuits for microcomputers, CPU and MPU.
2. Reset circuit for logic circuitry.
3. Level detecting circuit.
Pin Assignment
1
2
3
V
CC
GND
V
OUT
1
2
3
TO-92A
MITSUMI
System Reset PST993, 994
Equivalent Circuit Diagram
PST993
PST994
Absolute Maximum Ratings
Item
Storage temperature
Operating temperature
Supply voltage
Allowable loss
(Ta=25
°
C)
Symbol
T
STG
T
OPR
V
CC
Pd
Ratings
-40~+125
-20~+75
-0.3~10
300
Units
°
C
°
C
V
mW
Electrical Characteristics
Item
(Ta=25
°
C) (The unit of resistance is
Ω
unless otherwise indicated.)
Measurement
Circuit
Measurement conditions
PST993C
PST993D
PST993E
PST993F
PST993G
R
L
=∞
V
CC
=H L
PST993H
PST993I
PST993J
PST993K
PST993L
R
L
=∞, V
CC
=L H L
R
L
=∞, Ta=-20~+75
°
C
V
CC
=Vs min. -0.05V, R
L
=1k
V
O
=2.5V, V
CC
=5V, R
L
=∞
V
CC
=Vs min. -0.05V, R
L
=∞
V
CC
=Vs typ. /0.85V, R
L
=∞
C
L
=100pF
Min. Typ. Max. Units
4.27
4.00
3.70
3.42
3.13
2.94
2.75
2.56
2.37
2.18
30
4.5
4.2
3.9
3.6
3.3
3.1
2.9
2.7
2.5
2.3
50
±0.01
0.1
-25
250
300
20
1
1
0.65
0.4
-17
400
500
4.73
4.40
4.10
3.78
3.47
3.26
3.05
2.84
2.63
2.42
100
Symbol
V
Detection Voltage
V
S
1
Hysteresis Voltage
Detection Voltage
Temperature Coefficient
Low Level Output Voltage
Output Constant Current
Circuit Current at ON Time
Circuit Current at OFF Time
"H" Transmission Delay Time
"L" Transmission Delay Time
Operating Threshold Voltage
V
S
V
S
/ T
V
OL
I
O
C
I
CCL
I
CCH
tpLH
tpHL
V
OP
L
1
1
1
1
1
1
2
2
1
mV
%/
°
C
V
µA
µA
µA
µS
µS
V
mA
mA
-40
C
L
=100pF
R
L
=4.7k, V
OL
< 0.4V
=
R
L
=∞, V
O
=0.4V
Output Current at ON Time 1
6
I
O
L1
1
V
CC
=V
S
min. -0.05V
Ta=-20~+75
°
C, R
L
=∞
1
4
Output Current at ON Time 2
I
O
L2
V
O
=0.4V, V
CC
=Vs min. -0.05V
Do not apply onto the OUT terminal any voltage higher than that at the V
CC
terminal.
( 1) The tpLH is a function of the charging time of C
L
by output constant current.
The delay time of this IC is about 1 µS.
*
0.85
15
*
*
MITSUMI
System Reset PST993, 994
Absolute Maximum Ratings
Item
Storage temperature
Operating temperature
Supply voltage
Allowable loss
(Ta=25
°
C)
Symbol
T
STG
T
OPR
V
CC
Pd
Ratings
-40~+125
-20~+75
-0.3~10
300
Units
°
C
°
C
V
mW
Electrical Characteristics
Item
(Ta=25
°
C) (The unit of resistance is
Ω
unless otherwise indicated.)
Measurement
Circuit
Measurement conditions
PST994C
PST994D
PST994E
PST994F
R
L
=1k
PST994G
V
CC
=H L
PST994H
PST994I
PST994J
PST994K
PST994L
R
L
=1k, V
CC
=L H L
R
L
=1k, Ta=-20~+75
°
C
V
CC
=Vs min. -0.05V, R
L
=1k
V
CC
=10V
V
CC
=Vs min. -0.05V, R
L
=∞
V
CC
=Vs typ./0.85V, R
L
=∞
C
L
=100pF, R
L
=4.7k
C
L
=100pF, R
L
=4.7k
R
L
=4.7k, V
OL
< 0.4V
=
V
O
=0.4V
V
CC
=Vs min. -0.05V
Ta=-20~+75
°
C
V
O
=0.4V, V
CC
=Vs min.-0.05V
CC
L
Symbol
Min. Typ. Max. Units
4.27
4.00
3.70
3.42
3.13
2.94
2.75
2.56
2.37
2.18
30
4.5
4.2
3.9
3.6
3.3
3.1
2.9
2.7
2.5
2.3
50
±0.01
0.1
250
300
1
1
0.65
6
4
15
0.4
0.1
400
500
4.73
4.40
4.10
3.78
3.47
3.26
3.05
2.84
2.63
2.42
100
Detection Voltage
Vs
1
V
Hysteresis Voltage
Detection Voltage
Temperature Coefficient
Low Level Output Voltage
Output Leakage Current
Circuit Current at ON Time
Circuit Current at OFF Time
"H" Transmission Delay Time
"L" Transmission Delay Time
Operating Threshold Voltage
Output Current at ON Time 1
Output Current at ON Time 2
Vs
Vs/ T
V
OL
I
OH
I
CCL
I
CCH
tpLH
tpHL
V
OP
L
I
O
L1
I
O
L2
1
1
1
1
1
1
2
2
1
1
1
mV
%/
°
C
V
µA
µA
µA
µS
µS
V
mA
mA
0.85
not
onto the OUT
terminal.
*
Do The apply is a function ofterminal any voltage higher than that at the Vcurrent.
( 1)
tpLH
the charging time of C by output constant
*
The delay time of this IC is about 1 µS.
MITSUMI
System Reset PST993, 994
Equivalent Circuit Diagram
*
Since PST993 incorporates a constant current load, the pull-up resistance is not necessary.
Characteristics
V
S
vs. Ta
4300
4280
4260
4240
4220
4200
4180
4160
4140
4120
4100
V
O
pL vs. Ta
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
V
S
(mV)
VopL
(V)
-20-10 0 10 20 30 40 50 60 70
-20-10 0 10 20 30 40 50 60 70
Ta (
°
C)
Ta (
°
C)
V
S
vs. Ta
100
90
80
70
60
50
40
30
20
10
0
V
O
L vs. Ta
100
90
80
70
60
50
40
30
V
S
(mV)
V
O
L
(mV)
-20-10 0 10 20 30 40 50 60 70
-20-10 0 10 20 30 40 50 60 70
Ta (
°
C)
Ta (
°
C)
I
CC
H vs. Ta
440
400
360
I
CC
H
320
(µA)
280
240
200
160
I
O
C vs. Ta (PST993)
-20
-22
-24
-26
-28
-30
-32
-34
-36
-38
-40
PST993
PST994
I
O
C
(µA)
-20-10 0 10 20 30 40 50 60 70
-
20
-
10 0
10 20 30 40 50 60 70
Ta (
°
C)
Ta (
°
C)
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