M5295AFP [MITSUBISHI]
WATCHDOG TIMER; 看门狗定时器
| 型号： | M5295AFP |
| 厂家： | 
Mitsubishi Group |
| 描述： | WATCHDOG TIMER |
| 文件： | 总8页 (文件大小：119K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MITSUBISHI<Dig.Ana.INTERFACE>
M5295AL/P/FP
WATCHDOG TIMER
DESCRIPTION
PIN CONFIGURATION (TOP VIEW)
M5295A is a semiconductor integrated circuit which is
designed for System Reset to detect +5V power supply.
This IC keeps the operation microcomputer watching.
When the system is abnormal,it generates Reset output until the
system returns to normal states of the System.
It is possible to vary the two detective voltage by connecting the
resistor,so it is suitable to high quality and high performance
system.
ADJ2
RST2
Vcc
8
7
6
5
4
3
2
1
ADJ1
GND
RST1
TC
FEATURES
•Watch Dog Timer
•Power on Reset Timer
•Low circuit current 0.8mA(Typ,Vcc=5V)
•Wide Range of power supply
WD
Outline 8P5(AL)
1
2
3
4
8
7
6
5
ADJ2
WD
TC
APPLICATION
Microcomputer Systems
RST2
Vcc
RST1
GND
RECOMMENDED OPERATING CONDITIONS
ADJ1
Supply voltage...........................................4V to 15V
Rated supply voltage............................................5V
Outline 8P4(AP)
8P2S-A(AFP)
BLOCK DIAGRAM
49.6k
51.2k
-
+
F.F
-
F.F
+
-
20.4k
18.8k
+
W.D.T
F.F
1.24V
REFERENCE VOLTAGE
GENERATOR CIRCUIT
20k
30k
1
8
2
5
7
3
4
6
WD
Vcc
ADJ1
TC
RST1
GND
RST2
ADJ2
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MITSUBISHI<Dig.Ana.INTERFACE>
M5295AL/P/FP
WATCHDOG TIMER
ABSOLUTE MAXIMUM RATINGS (Ta=25°C,unless otherwise noted)
Conditions
Symbol
Ratings
Unit
V
Parameter
Supply voltage
Vcc
VIN
15
-10 to +10
15
Input voltage
V
Output voltage
V
VOUT
IOUT
10
Output current
mA
mW
mW/°C
°C
800(SIP)/625(DIP)/440(FP)
8(SIP)/6.25(DIP)/4.4(FP)
-20 to +75
Power dissipation
Thermal derating
Operating temperature
Pd
K
Ta³ 25°C
Topr
Tstg
-55 to +125
Storage temperature
°C
ELECTRICAL CHARACTERISTICS (Ta=25°C,Vcc=5V,unless otherwise noted)
(1)DC FEATURES
Limits
Parameter
Pin
Unit
mA
Symbol
Test conditions
Typ.
0.15
-0.1
Min.
0.06
0.05
2
Max.
0.25
-0.15
VIN=5V
IIH
IIL
WD
WD input current
mA
V
VIN=-5V
VIH
WD
WD input voltage
VIL
0.8
-1
V
µA
mA
IOUT
IIN
TC output current
TC input current
TC
TC
VIN=1.5V
3.3
4
VOUT=4.2V
VVH3(H)
VVH3(L)
3.7
1.7
4.3
2.3
0.5
5
V
Threshold voltage of watch dog timer
TC
2
V
V
0.1
Output voltage
VOL
IOUT=1mA
VOUT=15V
RST1
RST2
ILEAK
Output leak current
µA
V
VTH1
Vcc detective voltage(1)
Vcc
4.25
4.45
4.05
VTH2(H)
VTH2(L)
DVTH2
V5
4.5
4.45
0.05
1.17
1.07
4.7
4.6
4.9
4.75
0.2
V
V
Vcc detective voltage(2)
ADJ1 voltage
Vcc
0.1
V
V
ADJ1
ADJ2
RST1
1.75
1.61
0.5
1.46
1.34
V8
ADJ2 voltage
V
V
V
RST1 on voltage
RST1
Vcc=1.2V,RL=4.7k
Vcc=1.2V,RL=4.7k
0.5
RST2
Icc
RST2 on voltage
Circuit current
RST2
Vcc
0.8
V
1.5
(2)AC FEATURES
Limits
Typ.
Pin
Symbol
Parameter
Watch dog timer
Unit
Test conditions
Min.
0.5
Max.
1.7
s
1.1•C•R1
1.1
tWD
RST1
ms
C=0.1µF,R1=10kW
0.5•C•R1
0.5
s
ms
s
RST1
RST1
Reset timer (1)
tRST(1)
tRST(2)
1.1
C=0.1µF,R1=10kW
R1=10kW
0.2
830•C
83
Reset timer (2)
40
3
220
µs
µs
µs
µs
C=0.1µF,R1=10kW
tWD IN
td1
Input pulse watch
Transmittal delay time
WD
20
10
RST1
RST2
td2
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MITSUBISHI<Dig.Ana.INTERFACE>
M5295AL/P/FP
WATCHDOG TIMER
OPERATING EXPLANETION
VTH2(H)
VTH1
VTH2(L)
VTH1
Vcc
0V
VTH3(H)
VTH3(L)
0V
TC
VIN
0V
RST1
RST2
0V
0V
tRST(1)
tWD
tRST(2)
6
1 2 3
4
5
7 8
9
9 1011
In the case of entrance of abnormal signal input,
as the waveform of TC pin repeats charge and
discharge of Reset1 alternatively from 2V to 4V,the
Reset1 repeats high and low output operation.
The Vcc falls to 4.6V,then Reset2 generates Low,
this detective voltage has a 100mV hysteresis.
When Vcc goes down to 4.25V(VTH1),the status of
TC pin is switched to discharge.When the potentional
at TC pin is detected being VTH3(H) or VTH3(L),the
status of Reset1 becomes "low".
The Vcc rises up to 0.8V,then Reset1 and 2
generate Low output,and Rising up to 4.25V,charge
of C1 begins.
The Vcc rises up to 4.7V,then Reset2 generates
high.
The voltage at TC pin is 2V,then Reset2 generates
high,when 4V,C1 is discharged and Reset1
generates Low.
The voltage at TC pin falls to 2V,then Reset1
generates high unless normal clock signal is entered
to WD pin,Reset1 repeats this operation.
Before the voltage at TC pin reaches 4V,if normal
clock signal is entered to WD pin,Low Reset1 is
canceled.
1
8
,
2
4
10
11
3
6
,
5
7
,
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MITSUBISHI<Dig.Ana.INTERFACE>
M5295AL/P/FP
WATCHDOG TIMER
2.Pin 1 (WD Pin) Input Frequency,
Input Pulse Width,Charge Time and
Discharge Time
TERMINOLOGY
tRST1:Time required for TC pin potential to rise
from 0V VTH3(L) when Vcc is being applied.
tWD: Time required for TC pin potential to rise
from VTH3(L) to VTH3(H).
When input to WD pin 1 is normal,TC pin 2 output
waveform is as shown below:
(Vcc=5V)
tRST2:Time required for TC pin potential to go
down from VTH3(H) to VTH3(L).
4V
Pin 2 xV
1.Pin 2 (TC Pin) Charge Time and
Discharge Time
2V
t2
t1
When input to WD pin is abnormal,TC pin output
waveform is as shown below:
4
5
•Vcc
•Vcc
TC
Input
2
5
tWDIN
0V
tWD
3
5-x
t1=C•R1•in
(charge time)
R1
tRST(2)
tRST(1)
+1
x-5
1000
tRST(1)=0.51•C•R1
tWD=1.1•C•R1(charge time)
(discharge time)
t2=1000•C•in
R1
1000
2•
-3
R1
4•
-1
-3
tRST(2)=1000•C•in
1000
R1
1000
(discharge time)
PIN 1 (WD PIN)INPUT REQUIREMENTS
(1)Connect capacitor between WD pin and voltage input.
(Refer to Section 3.)
2•
Vcc
(2)Input cycle:No more than tWD
R1
(Discharge should start before voltage at WD pin
reaches 4V.)
2
C
1
f
<
1.1•C•R1
(3)Input pulse width tWDIN:No more than t2
Resistance R1:10kW£R1£30kW
When R1 is 10kW,tRST(2) is 830•C.
C=104
1ms
t1
t
C=103
100µs
Vcc=5V
R1=10kW
0.5
ms
50µs
t2
4
3
2
DISCHARGE VOLTAGE x(V)
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MITSUBISHI<Dig.Ana.INTERFACE>
M5295AL/P/FP
WATCHDOG TIMER
3.Relationship between Input Pulse
Width and Input Capacitance Cin
Vin
Vin
VIN
t
t4
When input to pin 1 is 1.5V or more,TC pin
discharges electricity. Determine pulse width and
input capacitance Cin with reference to the diagram
shown on the right.
WD
1
1.5V
t
t3
4V
TC
2
tWD
2V
t
VIN
30k
Q1
1
Cin
20k
RST1
3
t
Q1 is off when voltage at pin 1 is 1.5V or less.
Cin:10.000pF,t3=0.6ms
Cin:1000pF,t3=0.6µs
Cin:100pF,t3=6µs
Vin
1.5
t3=Cin•5X104•In
RST1 is output when t4 is longer than tWD.
When t3 is too long,TC pin output waveform frequency
changes as shown above.Set t3 to be sufficiently long
to turn on Q1[tWDIN(3µs)or more] but not to exceed
t2(Discharge time).
(t2:Discharge time during normal input)
VTH1(V)
13
R2(kW)
R1(kW)
10
Detection voltage calculation formula
R01+R02
0.92
1.25
1.96
3.17
4.Vcc Detection Voltage Adjustment
(1)Detection voltage 1(VTH1)adjustment.
VTH1=
X1.24(V)
10
10
R02
7
10
R01=R1//49.6kW
R02=R2//20.4kW
5
10
4.25
4
6
10.90
8.59
5
5
3.5
49.6k
20.4k
RL
R1
R2
To adjust detection voltage 1,determine external resistance
with the following equation:
+
-
5
3
a. VTH>4.25V(R1=10kW)
1.24V
1
8.322kX1.24
VTH1-1.24
R2=
R0=
R0=
1
1
4
-
R0
20.4k
b. VTH1<4.25V(R2=5kW)
(VTH1-1.24)4.016k
1.24
1
R1=
1
1
-
R0
49.6k
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MITSUBISHI<Dig.Ana.INTERFACE>
M5295AL/P/FP
WATCHDOG TIMER
(2)Detection voltage 2(VTH2(L))adjustment
DVTH2(mV)
VTH2(L)(V)
13
10
7
R3(kW)
10
R4(kW)
0.93
1.26
1.99
3.24
Detection voltage calculation formula
16.3
R03+R04
VTH2(L)=
X1.24(V)
10
16.3
16.3
R04
10
6
R03=R3//51.2kW
R04=R4//18.8kW
5
10
16.3
100
51.2k
R3
4.6
4
RL
R03
51.2k
5
5
17.2
10.61
8.38
DVTH2=
X100(mV)
+
-
5
7
3.5
14.1
R4
18.8k
To adjust detection voltage 2,determine external resistance
with the following equations:
1.24V
a. VTH2(L)>4.6V(R3=10kW)
4
1
8.37kX1.24
VTH2(L)-1.24
R4=
R0=
R0=
1
1
-
R0
18.8k
b. VTH2(L)<4.6V(R4=5kW)
APPLICATION EXAMPLE
(VTH2(L)-1.24)3.95k
1.24
1
R3=
1
1
-
R0
51.2k
M5295AL
1
2
3
4
5
6
7
8
CLOCK
RST1
(RESET)
RST2
(HOLD)
MCU/MPU
VDD
Example of Backup Circuit with M5295AL
BACKUP POWER SUPPLY
3.5V
OPERATION INSTRUCTIONS
M5295AL
1.When malfunction occurs due to noise or other related
trouble,connect capacitance of approximately 1000pF
between pin 5 and GND as well as pin 8 and GND to
stabilize operation.
10KW
R4
1
2
3
4
5
6
7
8
2.To adjust detection voltage,add resistance of 15kW
or less to both Vcc and GND via adjusting pins.
(Set detection voltage to no less than 3V.)
3.Set tWD and tRST(2) as shown below:
110µs£tWD£1.1s
R3
Vcc
Backup switching voltage
VTH(L)
Switching voltage calculation formula
TO SYSTEM
8.3µs£tRST(2)£83ms
10kW£R1£30kW
4.Input clock pulses to pin 1 via capacitor.To determine
capacitance,refer to "Relationship between Input Pulse
Width and Input Capacitance Cin".
RESET
OUTPUT
R03+R04
R04
R03=R3//51.2k
VTH2(L)=
X1.24
R04=R4//18.8k
(Note)Set backup switching voltage to be more
than or equal to backup supply voltage.
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MITSUBISHI<Dig.Ana.INTERFACE>
M5295AL/P/FP
WATCHDOG TIMER
TYPICAL CHARACTERISTICS
THERMAL DERATING
(MAXIMUM RATING)
DETECTION VOLTAGE VS.
SUPPLY VOLTAGE
4.9
1000
M5295AL
800
4.8
VTH2(H)
4.7
M5295AP
600
4.6
VTH2(L)
M5295AFP
400
4.5
4.4
VTH1
4.3
4.2
4.1
200
0
0
40 60 80 100
120
25
50
125
0
20
100
75
-40
-20
AMBIENT TEMPERATURE Ta(°C)
AMBIENT TEMPERATURE Ta(°C)
INTERRUPTION OUTPUT VOLTAGE VS.
CIRCUIT CURRENT
CIRCUIT CURRENT VS.
SUPPLY VOLTAGE
4.0
1.6
1.4
1.2
RL=4.7kW
3.5
Vcc=5V
3.0
2.5
1.0
0.8
0.6
0.4
0.2
0
RST1 High
2.0
1.5
1.0
RST2 High
0.5
0
(Icc FLUCTUATION CAUSED
BY CIRCUIT OPERATION)
16
8 10 12 14
6
0
2
4
100 120
20 40 60 80
-20
0
-40
SUPPLY VOLTAGE Vcc(V)
AMBIENT TEMPERATURE Ta(°C)
CRITICAL OPERATION VOLTAGE
CHARACTERISTICS
DELAY TIME VS.DELAY CAPACITY
CHARACTERISTICS
0.8
100
7
5
3
2
Vcc=5V
0.7
0.6
tWD(R1=10kW)
10
1
7
5
3
2
0.5
0.4
0.3
tRST2
RL=2.2kW
RL=22kW
RL=100kW
7
5
3
2
0.2
0.1 7
5
3
2
0.1
0
0.01
3
3 5 7
5 710 2
2
0
0.4 0.6 0.8 1.0 1.2 1.4 1.6
3
3 5 70.12
0.012
5 7 1
0.2
100
SUPPLY VOLTAGE Vcc(V)
DELAY CAPACITY C(µF)
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MITSUBISHI<Dig.Ana.INTERFACE>
M5295AL/P/FP
WATCHDOG TIMER
OUTPUT SATURATION VOLTAGE VS.
AMBIENT TEMPERATURE
OUTPUT SATURATION VOLTAGE VS.
LOAD CURRENT
0.4
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
Vcc=5V
RL=4.7kW
Vcc=5V
0.3
0.2
0.1
0
-40
60 80
3
2
-20
20
120
100
40
0
3
5
7
3
2
5 7
2
1
10
5 7 100
0.1
AMBIENT TEMPERATURE Ta(°C)
LOAD CURRENT IOUT(mA)
WATCHDOG TIMER THRESHOLD VOLTAGE
PIN TC INPUT CURRENT VS.
AMBIENT TEMPERATURE
VS. AMBIENT TEMPERATURE
8
8
7
6
5
4
3
2
1
0
Vcc=5V
7
6
5
4
3
2
1
Vcc=5V
VTH3(H)
VTH3(L)
0
-40
20
60 80
100
-20
120
0
40
-40
60 80
-20
20
40
100 120
0
AMBIENT TEMPERATURE Ta(°C)
AMBIENT TEMPERATURE Ta(°C)
WATCHDOG TIMER VS.
AMBIENT TEMPERATURE
RESET TIMER(2) VS.
AMBIENT TEMPERATURE
1.6
320
280
240
200
160
120
80
Vcc=5V
C=0.1µF
R1=10kW
Vcc=5V
C=0.1µF
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
40
0
-40
60 80
-20
20
40
100 120
0
-40
20
60 80
100
-20
120
0
40
AMBIENT TEMPERATURE Ta(°C)
AMBIENT TEMPERATURE Ta(°C)
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