MITSUMI PST623

System Reset PST623
MITSUMI
System Reset
Monolithic IC PST623
Outline
This low reset type IC functions in CPU and other logic systems to detect input voltage and reset the system
accurately when power is turned on or interruped.
Features
1.
2.
3.
4.
5.
6.
7.
Detection voltage can be set easily (2 external resistors)
High percision voltage detection Internal reference voltage
Enables high voltage check (at stage before Reg)
Low operating limit voltage
High output current during ON
Low current consumption
Built-in delay circuit (1 external capacitor)
1.25±2%
0.65V typ.
10mA min.
40µA typ.
Applications
1. Reset circuits in microcomputers, CPUs and MPUs
2. Logic circuit reset circuits
3. Level detection circuits
Package
VSOP-8A (PST623XS)
SIP-5A (PST623XW)
Pin Assignment
8
1
7
2
6
3
VSOP-8A
5
4
1
VS
2
NC
3
TC
4
GND
5
RESET
6
NC
7
NC
8
VCC
1
2
3
SIP-5A
4
5
1
VCC
2
VS
3
TC
4
GND
5
RESET
System Reset PST623
MITSUMI
Absolute Maximum Ratings
(Ta=25°C)
Item
Storage temperature
Maximum power supply voltage
Allowable power consumption
Input pin voltage
Symbol
TSTG
VCC max.
Pd max.
VID
Rating
-40~+125
10
300
-0.3~VCC
Units
°C
V
mW
V
Rating
2.0~10.0
-25~+75
Units
V
°C
Recommended Operating Conditions
Item
Power supply voltage
Operating temperature
Electrical Characteristics
Symbol
VCCOP
TOPG
(Except where noted otherwise, VCC=5V, Ta=25°C)
Item
Detection reference voltage
Hysteresis voltage
Detection reference voltage
temperature coefficient
L level output voltage
Output leakage current
Circuit current while on
Circuit current while off
"H" transport delay time
"L" transport delay time
Symbol
VS
VS
Measurement conditions
RL=470Ω, VIN=H L
RL=470Ω, VIN=L H L
Vs
T
RL=470Ω, Ta=-25~+75°C
±0.01
VOL
IOH
ICCL
ICCH
tpLH
tpHL
0.3
Operation limit voltage
VOPL
Output current while on
Delay time setting comparator
Threshold level
Capacitor charging current
Vs input current
IOL
VIN=1.0V, RL=470Ω
VIN=1.5V, VOUT=10V
VIN=1.0V, RL=∞
VIN=1.5V, RL=∞
RL=4.7kΩ, Cd=0.047uF
RL=4.7kΩ, Cd=0.047uF
RL=4.7kΩ, VOL =< 0.4V
Minimum power supply voltage for
which output can maintain Lo.
VIN=1.0V, RL=0
Vtsh
ITC
IIN
RL=470Ω, VTC=L
VIN=1.5V, VTC=0.2V
VIN=1.35V
Equivalent Circuit Diagram
VSOP-8A
H
SIP-5A
Min. Typ. Max. Units
1.225 1.25 1.275 V
12
25
50
mV
50
42
110
15
0.65
%/°C
0.45
±0.1
90
70
V
µA
µA
µA
mS
µS
0.85
V
10
mA
1.25
1.4
1.55
V
0.39
0.60
40
0.81
µA
nA
System Reset PST623
MITSUMI
Notes on Using PST623
1. Input voltage rise and fall
VS+0.4V
VS
VS-0.4V
30µS
Be sure to give an incline of more than 30µS to rise and fall for input with varied power supply voltage (VCC)
and bleeder resistance.
Also, when setting input bleeder resistance, VS pin input current is affected and the detection voltage setting
will differ from the set value if current on the bleeder resistor is too low.
Use input bleeder resistor R2 at 250kΩ or less.
2. Delay time setting
H transmission delay time can be set easily as follows from the TC pin, using the external capacitor.
T = Cd (2.33 106) [S]
Use the external capacitor at 1µF (approx. 2.33S) or less.
Characteristics
Current consumption for OFF
70
65
60
55
50
45
40
35
30
25
20
15
Detection voltage (V)
ICC
(µA)
Detection voltage
0
1
2
3
4
5
6
7
8
2
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1
-30
9 10
VCC (V)
H transport delay time (S)
101
100
10-1
10-2
10-3
10-4
10-3
10
30
50
H transport delay time (S)
H transport delay time
10-4
10-5
-10
10-2
Capacitance (µF)
10-1
100
70
System Reset PST623
MITSUMI
Application Circuits
1. Circuit Diagram
2. Detection Voltage Setting
R1+R2
VS ·=· 1.25 · ——————
R2
* Note
The value of I2 should be sufficient to ignore I3.
Make I2 > 5µA.
R2 < 250kΩ
3. How to widen hysteresis
Voltage VIN1 so that Q1 ON goes OFF.
(R1+R2)
R1//R2
VIN1=————————— [1.25 (V) · (R3+R1//R2+R4//R5) - ———— (R4 · VBE+R5 · VCC)]
R2 · (R3+R4//R5)
R4+R5
Voltage VIN2 so that Q1 OFF goes ON.
(R1+R2)
VIN2=————— [1.275 (V) · (R1//R2+R3) -VOL · (R1//R2)]
R2 · R3
VOL: Low level output voltage
VBE: Base-emitter voltage of transistor Q1
R1//R2
R1 · R2
————
R1+R2
R4//R5
R4 · R5
————
R4+R5