CAT823, CAT824, CAT825
System Supervisory Voltage
Reset with Watchdog and
Manual Reset
Description
The CAT823, CAT824, and CAT825 provide basic reset and
monitoring functions for the electronic systems. Each device monitors the
system voltage and maintains a reset output until that voltage reaches
the device’s specified trip value and then maintains the reset output
active condition until the device’s internal timer, after a minimum
timer of 140 ms; to allow the systems power supply to stabilize.
The CAT823 and CAT824 also have a watchdog input which can be
used to monitor a system signal and cause a reset to be issued if the
signal fails to change state prior to a timeout condition.
The CAT823 and CAT825 also provide a manual reset input which
can be used to initiate reset if pulled low. This input can be directly
attached to a push−button or a processor signal.
Features
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SC−70
SD SUFFIX
CASE 419AC
TSOT−23
TD SUFFIX
CASE 419AE
PIN CONNECTIONS
RESET
GND
MR
1
1
V
CC
CAT823
WDI
•
•
•
•
•
•
•
•
Automatically Restarts Microprocessor after Power Failure
Monitors Pushbutton for External Override
Accurate Under Voltage System Monitoring
Brownout Detection System Reset for use with 3.0, 3.3, and 5.0 Volt
Systems
Pin and Function Compatible with the MAX823/24/25 Products
Operating Range from
−40°C
to +85°C
Available in TSOT−23 5−lead and SC−70 Packages
These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
Microprocessor and Microcontroller Based Systems
Intelligent Instruments
Control Systems
Critical
mP
Monitors
Portable Equipment
RESET
GND
RESET
V
CC
CAT824
WDI
RESET
GND
RESET
1
V
CC
CAT825
MR
(Top Views)
Applications
•
•
•
•
•
MARKING DIAGRAM
XXXMG
G
XXX
M
G
= Specific Device Code
= Date Code
= Pb−Free Package*
PIN FUNCTIONS
Pin Name
RESET
GND
MR
Function
CMOS Push−Pull Active Low Reset Output
Ground
Manual Reset input – Pulled high Internally by a 52 kW res-
istor designed to be driven low by a mechanical pushbutton,
open drain output or CMOS output.
CMOS Push−Pull Active High Reset Output
Watchdog Timer Input – Designed to be driven by a processor
output or can be disabled by tri−stating or leaving open.
Power Supply
(*Note: Microdot may be in either location)
RESET
WDI
V
CC
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 11 of this data sheet.
©
Semiconductor Components Industries, LLC, 2012
May, 2012
−
Rev. 8
1
Publication Order Number:
CAT823/D
CAT823, CAT824, CAT825
V
CC
WDI*
LEVEL SENSE
&
TIMER
TIMEOUT
COMPARATOR
RESET
V
CC
V
CC
TOLERANCE
BIAS
+
–
DIGITAL
DELAY
V
CC
V
CC
VOLTAGE
REFERENCE
52 kW
RESET*
MR*
LEVEL SENSE
&
DEBOUNCE
* Functions Available by Device
Figure 1. Block Diagram
Device
CAT823
CAT824
CAT825
RESET
x
x
x
x
x
x
RESET
MR
x
WDI
x
x
Table 1. ABSOLUTE MAXIMUM RATINGS
Parameters
Supply Voltage
All other pins
Input Current, V
CC
Output Current RESET, RESET
Continuous Power Dissipations (T
A
= +70°C)
SC−70 5−lead (derate 3.1 mW/°C above +70°C)
TSOT−23 5−lead (derate 7.1 mW/°C above +70°C)
Storage Temperature
Operating Ambient Temperature
Lead Soldering (10 seconds max)
ESD Rating: Low Voltage Pins
Human Body Model
Machine Model
Ratings
6
−0.3
to (V
CC
+ 0.3)
20
20
247
571
−65
to 150
−40
to +85
+300
2000
200
°C
°C
°C
V
Units
V
V
mA
mA
mW
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
Table 2. RECOMMENDED OPERATING CONDITIONS
Parameter
V
CC
(T
A
= 0°C to +70°C)
V
CC
(T
A
=
−40°C
to +85°C)
All Other Pins
Ambient Temperature
Range
1.0 to 5.5
1.2 to 5.5
−0.1
to (V
CC
+ 0.1)
−40
to +85
Units
V
V
V
°C
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2
CAT823, CAT824, CAT825
Table 3. ELECTRICAL OPERATING CHARACTERISTICS
(DC Characteristics: V
CC
= 3.0 V to 5.5 V for L/M versions;
V
CC
= 2.0 V to 3.6 V for the R/S/T/U/Y/Z version,
−40°C
≤
T
A
≤
+85°C unless otherwise noted. Typical Values at T
A
= 25°C and V
CC
= 5 V
for L/M versions; V
CC
= 3.3 V for the T/S versions; V
CC
= 3.0 V for the R version; and V
CC
= 2.5 V for the U/Y/Z versions.) (Note 1)
Symbol
I
CC
Parameter
Supply Current
Conditions
CAT823 (L/M Versions)
CAT824 (L/M Versions)
CAT823 (R/S/T/Y/Z Versions)
CAT824 (R/S/T/U/Y/Z Versions)
CAT825 (L/M Versions)
CAT825 (R/S/T/Y/Z Versions)
V
RST
Reset Threshold
CAT82_L at
−40°C
≤
T
A
≤
+85°C
CAT82_M at
−40°C
≤
T
A
≤
+85°C
CAT82_T at
−40°C
≤
T
A
≤
+85°C
CAT82_S at
−40°C
≤
T
A
≤
+85°C
CAT82_R at
−40°C
≤
T
A
≤
+85°C
CAT82_Z at
−40°C
≤
T
A
≤
+85°C
CAT82_Y at
−40°C
≤
T
A
≤
+85°C
CAT824U at
−40°C
≤
T
A
≤
+85°C
Reset Threshold Tempco
Reset Threshold Hysteresis
CAT82_L/M
CAT82_R/S/T/Y/Z, CAT824U
t
RD
t
RP
V
OH
V
CC
to Reset Delay (Note 2)
Reset Active Timeout Period
RESET Output High Voltage
CAT82_L/M, V
CC
= V
RST max
,
I
SOURCE
=
−120
mA
CAT82_T/S/R/Z/Y, CAT824U,
V
CC
= V
RST max
, I
SOURCE
=
−30
mA
V
OL
RESET Output Low Voltage
CAT82_L/M, V
CC
= V
RST min
,
I
SINK
= 3.2 mA
CAT82_T/S/R/Z/Y, CAT824U,
V
CC
= V
RST min
, I
SINK
= 1.2 mA
T
A
= 0°C to +70°C, V
CC
= 1 V,
V
CC
falling, I
SINK
= 50
mA
T
A
= T
MIN
to T
MAX
, V
CC
= 1.2 V,
V
CC
falling, I
SINK
= 100
mA
I
SOURCE
V
OH
V
OL
RESET Output
Short−Circuit Current
Reset Output Voltage
CAT82_L/M, Reset = 0 V, V
CC
= 5.5 V
CAT82_L/M, Reset = 0 V, V
CC
= 3.6 V
V
CC
> 1.8 V, I
SOURCE
=
−150
mA
CAT824L/M & CAT825L/M,
V
CC
= V
RST max
, I
SINK
= 3.2 mA
CAT824R/S/T/U/Y/Z &
CAT825R/S/T/Y/Z,
V
CC
= V
RST max
, I
SINK
= 1.2 mA
1.
2.
3.
4.
0.8 x V
CC
0.4
0.3
V
CC
= V
TH
to (V
TH
−
100 mV)
140
V
CC
−
1.5 V
0.8 x V
CC
0.4
0.3
0.3
0.3
1.5
0.8
V
mA
V
4.50
4.25
3.00
2.85
2.55
2.25
2.13
1.95
Min
Typ
6
4
3
2
4.63
4.38
3.08
2.93
2.63
2.32
2.19
2.00
40
10
5
20
200
400
ms
ms
V
Max
17
12
8
6
4.75
4.50
3.15
3.00
2.70
2.38
2.25
2.05
ppm/°C
mV
V
Units
mA
Over−temperature limits are guaranteed by design and not production tested.
The RESET short−circuit current is the maximum pull−up current when reset is driven low by a bidirectional output.
WDI is internally serviced within the watchdog period if WDI is left open.
The WDI input current is specified as an average input current when the WDI input is driven high or low. The WDI input if connected to
a three−stated output device can be disabled in the tristate mode as long as the leakage current is less than 10
mA
and a maximum capacitance
of less than 200 pF. To clock the WDI input in the active mode the drive device must be able to source or sink at least 200
mA
when active.
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CAT823, CAT824, CAT825
Table 3. ELECTRICAL OPERATING CHARACTERISTICS
(DC Characteristics: V
CC
= 3.0 V to 5.5 V for L/M versions;
V
CC
= 2.0 V to 3.6 V for the R/S/T/U/Y/Z version,
−40°C
≤
T
A
≤
+85°C unless otherwise noted. Typical Values at T
A
= 25°C and V
CC
= 5 V
for L/M versions; V
CC
= 3.3 V for the T/S versions; V
CC
= 3.0 V for the R version; and V
CC
= 2.5 V for the U/Y/Z versions.) (Note 1)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
WATCHDOG INPUT (CAT823 & CAT824)
t
WD
t
WDI
V
IL
V
IH
WDI Input Current (Note 4)
WDI = V
CC
, Time Average
WDI = 0 V, Time Average
MANUAL RESET INPUT (CAT823 & CAT825)
V
IL
V
IH
t
PB
t
PDLY
MR Pulse Width
MR low to Reset Delay
MR Noise Immunity
MR Pullup Resistance
(internal)
1.
2.
3.
4.
Pulse Width with No Reset
35
100
52
75
MR Input Voltage
0.7 x V
CC
1
5
ms
ms
ns
kW
0.3 x V
CC
V
−20
Watchdog Timeout Period
WDI Pulse Width
WDI Input Voltage (Note 3)
0.7 x V
CC
120
−15
160
mA
V
IL
= 0.4 V, V
IH
= 0.8 x V
CC
1.12
50
0.3 x V
CC
1.60
3.20
s
ns
V
Over−temperature limits are guaranteed by design and not production tested.
The RESET short−circuit current is the maximum pull−up current when reset is driven low by a bidirectional output.
WDI is internally serviced within the watchdog period if WDI is left open.
The WDI input current is specified as an average input current when the WDI input is driven high or low. The WDI input if connected to
a three−stated output device can be disabled in the tristate mode as long as the leakage current is less than 10
mA
and a maximum capacitance
of less than 200 pF. To clock the WDI input in the active mode the drive device must be able to source or sink at least 200
mA
when active.
TYPICAL ELECTRICAL OPERATING CHARACTERISTICS
NORMALIZED RESET THRESHOLD (V)
9
8
SUPPLY CURRENT (mA)
7
6
5
4
3
2
1
−40
−20
0
20
40
60
80
100
120
1.06
1.04
1.02
1.00
0.98
0.96
0.94
−40
−20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
Figure 2. V
CC
Supply Current vs. Temperature
Figure 3. Normalized Reset Threshold Voltage
vs. Temperature
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CAT823, CAT824, CAT825
FUNCTIONAL DESCRIPTION
Processor RESET
Manual RESET
The CAT823−825 detect supply voltage (V
CC
) conditions
that are below the specified voltage trip value (V
RST
) and
provide a reset output to maintain correct system operation.
On power−up, RESET (and RESET if available) are kept
active for a minimum delay t
RP
of 140 ms after the supply
voltage (V
CC
) rises above V
RST
to allow the power supply
and processor to stabilize. When V
CC
drops below the
voltage trip value (V
RST
), the reset output signals RESET
(and RESET) are pulled active. RESET (and RESET if
available) is specifically designed to provide the reset input
signals for processors. This provides reliable and consistent
operation as power is turned on, off or during brownout
conditions by maintaining the processor operation in known
conditions.
MR
Supply
Voltage
V
CC
The CAT823 and CAT825 each have a Manual Reset
(MR) input to allow for alternative control of the reset
outputs. The MR input is designed for direct connection to
a pushbutton (see Figure 4). The MR input is internally
pulled up by 52 kW resistor and must be pulled low to cause
the reset outputs to go active. Internally, this input is
debounced and timed such that RESET (and RESET)
signals of at least 140 ms minimum will be generated. The
min 140 ms t
RP
delay commences as the Manual Reset input
is released from the low level. (see Figure 5)
RESET
GND
RESET
CAT825
Figure 4. Pushbutton RESET
MR
t
PDLY
V
IL
t
PB
V
IH
t
RP
RESET
V
OH
V
OL
RESET
Figure 5. Timing Diagram – Pushbutton RESET
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