Page 1
MITSUMI
1432
8567
SOP-8C/DIP-8B
System Reset (with built-in watchdog timer) MM1095
System Reset (with built-in watchdog timer)
Monolithic IC MM1095
Outline
This IC functions in a variety of CPU systems and other logic systems to generate a reset signal and reset the
system accurately during momentary interruption or lowering of power supply voltage.
It also has a built-in watchdog timer for operation diagnosis. This prevents the system from running wild by
generating an intermittent reset pulse during system mis-operation.
Features
1. Built-in watchdog timer
2. Low minimum operating voltage 100µA typ.
3. Low operating limit voltage Vcc=0.8V
4. Watchdog stop function (RCT pin)
5. Few external parts
Package
DIP-8B (MM1095AD, MM1095BD)
SOP-8C (MM1095AF, MM1095BF)
SIP-8A (MM1095AS, MM1095BS)
Applications
1. Reset circuits in microcomputers, CPUs and MPUs
2. Logic circuit reset circuits
3. Microcomputer system monitoring, etc.
Pin Assignment
1 TC
2 NC
3 CK
1 TC
2 NC
3 CK
4 GND
5 V
6 RCT
7 V
8 RESET
CC
S
------------------------------------------
13572468
SIP-8A
4 GND
5 V
6 RCT
7 V
8 RESET
CC
S
------------------------------------------
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MITSUMI
System Reset (with built-in watchdog timer) MM1095
Pin Description
Pin No. Name Function
TWD, TWR, TPR variable pins
1 TC
(T
WD, TWR and TPR times are determined TWD (mS)=500 CT (µF)
by the external capacitor.) T
2 N.C
3 CK
4 GND
5 V
6 RCT
7 V
------------------------------------------------------------------------------------
8 RESET
Clock input pin, inputs clock from logic system
GND pin
CC
Voltage detection MM1095A 3.2V, MM1095B 4.2V
Watchdog timer stop pin Operation modes : Operation OPEN, Stop connect to GND
S
Detection voltage variable pin
Reset output pin (low output)
Absolute Maximum Ratings
Item Symbol Rating Units
Power supply voltage V
CK pin input voltage V
S pin input voltage VVS
V
Voltage applied to RCT pin V
Voltage applied to RESET
Allowable loss Pd 400 mW
Storage temperature T
--------------------------------------------
.
CC max.
CK
RCT
pin VOH
STG
TPR (mS)=5000 CT (µF)
WR (mS)=100 CT (µF)
-
0.3~+10 V
-
0.3~VCC+0.3 (
-
0.3~VCC+0.3 (
-
0.3~VCC+0.3 (
-
0.3~VCC+0.3 (
-
40~+125 °C
<
+10) V
=
<
+10) V
=
<
+10) V
=
<
+10) V
=
Recommended Operating Conditions
Item Symbol Rating Units
Power supply voltage V
-------------------------------------------
RESET
sync current IOL 0~1.0 mA
Clock monitoring time setting T
Clock rise and fall times t
TC pin capacitance C
Operating temperature T
CC +2.2~+7.0 V
WD 0.1~1000 mS
FC, tRC <100 µS
T 0.0002~2 µF
OP
-
25~+75
°
C
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MITSUMI
System Reset (with built-in watchdog timer) MM1095
Electrical Characteristics (DC)
(Except where noted otherwise, MM1095A : Vcc=3.6V, Ta = 25°C, MM1095B: Vcc=5.0V)
Item Symbol Measurement conditions Min. Typ. Max. Units
Consumption
current
MM1095A
CC During watchdog timer operation
I
MM1095B 130 195
MM1095A
SL
V
VS=OPEN, VCC
3.10 3.20 3.30
100 150
Detection MM1095B 4.05 4.20 4.35
voltage MM1095A
SH
V
VS=OPEN, VCC
3.15 3.25 3.35
MM1095B 4.15 4.30 4.45
Detection voltage
V
S/ T ±0.01 %/
temperature coefficient
Hysteresis voltage
MM1095A
HYS
V
VSH-VSL, VCC
25 50 100
MM1095B 50 100 150
CK input threshold V
TH 0.8 1.2 2 V
I
IH A : VCK=3.6V, B : VCK=5.0V 0 1
CK input current
IL VCK=0V
I
Output voltage
MM1095A
OH
V
(High) MM1095B V
V
OL1 I =0.5mA, VS=0V 0.2 0.4
Output voltage (Low)
OL2 I =1.0mA, VS=0V 0.3 0.5
V
R output sync current I
T charge current
C
OL V =1.0V, VS=0V 1 2 mA
I
I
CT1
CT2
VTC=1.0V during watchdog timer operation-1.60-2.40-4.80 µA
VTC=1.0V during power ON reset operation-0.16-0.24-0.48 µA
Minimum operating power
supply voltage to ensure RESET
--------------------------------------------------------------------------
VCCL 0.8 1.0 V
------------------------------------------
RESET
I=-1µA 3.0 3.4
S=OPEN 4.0 4.5
------------------------------------------
RESET
------------------------------------------
RESET
------------------------------------------
RESET
------------------------------------------
RESET
V =0.4V
------------------------------------------
RESET
I =0.1mA
-
12
µA
V
°
C
mV
µA
-
6
-
2
V
V
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MITSUMI
System Reset (with built-in watchdog timer) MM1095
Electrical Characteristics (DC)
Item Symbol Measurement conditions Min. Typ. Max. Units
CC input
V
pulse width
CK input pulse width T
CK input cycle T
Watchdog timer
monitoring time
Reset time for
watchdog timer
Reset hold time for
power supply rise
Output delay time from V
Output rise time
Output fall time
Notes:
1 Monitoring time is the time from the last pulse (negative edge) of the timer clear clock pulse until reset
*
pulse output. In other words, reset output is output if a clock pulse is not input during this time.
2 Reset time means reset pulse width. However, this does not apply to power ON reset.
*
3 Reset hold time is the time from when VCC exceeds detection voltage (VSH) during power ON reset until
*
reset release (RESET
4 Output delay time is the time from when power supply voltage drops below detection voltage (VSL) until
*
reset (RESEToutput low).
5 Voltage range when measuring output rise and fall is 10~90%.
*
6 Watchdog timer monitoring time (TWD), watchdog timer reset time (TWR) and reset hold time (TPR) during
*
power supply rise can be changed by varying C
formulae.
MM1095A 8
T
MM1095B 8
CKW 3µS
CK 20 µS
T
1
*
2
*
3
*
CC
5 tR RESET
*
5 tF RESET
*
-------------------------------------------------------------------------------
WD CT=0.02µF 5 10 15 mS
T
WR CT=0.02µF 1 2 3 mS
T
PR 50 100 150 mS
4
TPD RESET
*
output high).
VCC
PI µS
VCC
CT=0.02µF, VCC
(Except where noted otherwise, MM1095A : V
3.6V
2.8V
5.0V
4.0V
CK or
VCC
-------------------------------------------------------------------------------
pin, RL=10kΩ, CL=20pF 2 10 µS
-------------------------------------------------------------------------------
pin, RL=10kΩ, CL=20pF 2.0 4.0 µS
-------------------------------------------------------------------------------
pin, RL=10kΩ, CL=20pF 0.2 1.0 µS
T capacitance. The times are expressed by the following
CC
=3.6V, Ta=25°C, MM1095B : VCC=5.0V)
PR (mS)
T
T
WD (mS)
T
WR (mS)
.
=.5000 CT (µF)
.
=.500 CT (µF)
.
=.100 CT (µF)
Example: When C
T
T
T
.
PR
=.100mS
.
WD
=.10mS
.
WR
=.2mS
T=0.02µF
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MITSUMI
System Reset (with built-in watchdog timer) MM1095
Measuring Circuits
Measuring Circuit 1(DC) Measuring Circuit 2 (AC)
Measuring Circuit 1
Item
Consumption current I
Detection voltage
CK input threshold V
CK input current
Output voltage (High) VOH ON OFF ON ON ON ON A 3.6V 3.6V 2V
Output voltage (Low)
Output sink current I
T charge current 1 ITC1 OFF OFF OFF ON ON OFF A 3.6V
C
CT charge current 2 ITC2 OFF OFF OFF ON ON OFF A 3.6V
Minimum operating power
supply voltage to ensure RESET
Symbol
V
V
VCCL ON OFF ON ON ON ON A
--------------------------------------------------
Measuring Circuit 2
Item
CC input pulse width TP1C B
V
CK input pulse width T
CK input cycle T
Watchdog timer
monitoring time CRT2
Reset time for
watchdog timer CRT2
Reset hold time for
power supply rise CRT2
Output delay time
CC
from V
Output rise time T
Output fall time T
Symbol
T
T
T
TPD CA
SW & Power Supply Table
-------------------------------------------------------
1V
1V
1V
RESET
-
-
-
-
-
-
-
1µA VO1
-
-
-
-
SW1 SW2 SW3 SW4 SW5 SW6 SW7 VCC VCK VCT I VM, IM Notes
CC OFF OFF OFF ON ON ON A 3.6V 3.6V 0V
SL OFF OFF ON ON ON ON A
V
V
SH OFF OFF ON ON ON ON A
TH OFF OFF OFF ON ON ON A 3.6V
IH OFF OFF OFF ON ON ON A 3.6V 3.6V 0V
I
3.6V 3V
3V 3.6V
0V 2V
0V 2V
0V 3V
IIL OFF OFF OFF ON ON ON A 3.6V 0V 0V
OL1 ON ON ON ON ON ON A 3.6V 3.6V 2V 0.5mA VO1
OL2 ON ON ON ON ON ON A 3.6V 3.6V 2V 1.0mA VO1
OL1 OFF ON ON ON ON ON B 3.6V 3.6V 2V
-
-
0V 2V
0V 0V
SW & Power Supply Table
SW1 SW2 VCCA VCC VCKA VCK CRT Notes
T2 T3
T2
or
T2 T3
-
-
-
-
-
T2
3.6V
3.6V
3.6V
0V CRT1
3.6V CRT1
3.6V CRT1
CKW AB
CK AB
WD AA
WR AA
PR
B A
A
R AA
F AA
3.6V
2.5V
3.6V
0V
T1
-
-
-
-
-
1.4V
-0V
1.4V
3.6V
0V
1.4V
3.6V
0V
3.6V
3.6V
3.6V
--
-
-
3.6V
3.6V
-
-
ICC
VO1, CRT1
VO1, CRT1
ICK, VCK
ICK
ICK
IO1VO=1V
ITC
ITC
VO1, VCC
CRT1
CRT2
CRT1
CRT2
CRT1
CRT2
T3=20µS
CRT1
CRT1
CRT1
T1=8µS
T2=3µS
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MITSUMI
VCC
CK
C
T
RESET
VSL
VSH
TCK
TPR
TWD
TWR
TPR
1 2 3 4 5 5 6 7 8 9 10 11
12
Block Diagram
System Reset (with built-in watchdog timer) MM1095
RA RB
MM1095A
MM1095B
~
~
-
305k
350k
~
~
-
195k
150k
Timing Chart
Note 1 : CP=0.1µF approx.
Note 2 : C=1000pF
Note 3 : The watchdog timer can be stopped by connecting the RCT pin to GND.
(Then it functions as a voltage detection circuit.)
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MITSUMI
System Reset (with built-in watchdog timer) MM1095
Description of Operation
-------------------------------------------------
1. RESET
2. Capacitor C
reset state at this time.
3. Output reset is released (RESET
discharge (the time from when C
drops to a certain threshold value 2 (.=.0.2V). Approximately 1µA (V
from RESET.
Reset hold time : T
T
C
4. If a clock is input (negative edge trigger) to the CK pin during C
5. Discharge switches to charging when C
are repeated while a normal clock is input from the logic system.
6. Output goes to reset state (RESET
threshold value (.=.1.4V).
The formula for C
T
7. Watchdog timer reset time T
(.=.0.2V). The formula is as follows.
T
After reset OFF threshold value is reached, output reset is released and C
steps 4 and 5 are repeated if a normal clock is input, and when the clock ceases, 6 and 7 are repeated.
8. Reset is output when V
simultaneously.
9. C
When Vcc drops momentarily, C
dropping below VSL until it rises to VSH is longer than the VCC input pulse width standard value TPI.
10.Output reset is released after V
8~10 are repeated when V
11.When power is OFF, reset is output if V
12.When V
goes low when VCC rises to approximately 0.8V.
T charging starts when VCC rises to VSH (MM1095A
---------------------------------------------
PR (mS)
T charging starts again after reset release, and watchdog timer operation begins.
WD (mS)
WR (mS)
T charging starts when VCC rises to VSH.
.
=.5000 CT (µF)
.
=.500 CT (µF)
.
=.100 CT (µF)
CC drops to 0V, reset output is held until VCC reaches 0.8V.
PR is as follows.
T charging time (TWD: watchdog timer monitoring time) until reset is output is as follows.
CC drops to VSL (MM1095A
goes high) after a certain time (TPR), from when CT starts charging until
T voltage reaches a certain threshold value 1 (
T voltage drops to a certain threshold value (
---------------------------------------------
CC goes below VSL.
goes low) when the clock ceases and CT voltage reaches reset ON
WR is the discharge time until CT voltage drops to reset OFF threshold value
.
=.3.2V, MM1095B .=.4.2V). CT is charged
T charging begins after the charge is first discharged, if the time from VCC
CC goes above VSH and after TPR, and the watchdog timer starts. Thereafter,
CC goes below VSL.
.
=.3.25V, MM1095B .=.4.3V). Output is in
.
=.1.4V) until CT voltage
CC=0.8V) of pull up current is output
T charging, charging switches to discharge.
T starts charging. Thereafter,
.
=.0.2V). Steps 4 and 5
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