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CAT823, CAT824, CAT825
System Supervisory Voltage Reset with
Watchdog and Manual Reset
FEATURES
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
For Ordering Information details, see page 13.
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 140ms; 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.
APPLICATIONS
Microprocessor and Microcontroller based
systems
Intelligent Instruments
Control Systems
Critical µP Monitors
Portable Equipment
PIN CONFIGURATION
TSOT-23 5-Lead
SC-70 5-Lead
RESET
GND
MR
1
2
3
5
VCC
RESET
GND
4
WDI
RESET
1
2
3
5
VCC
PIN FUNCTIONS
Pin Name
¯¯¯¯¯¯
RESET
GND
Function
CMOS Push-Pull Active Low Reset
Output
Ground
Manual Reset input – Pulled high
Internally by a 52kΩ resistor 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
CAT823
CAT824
4
WDI
¯¯¯
MR
RESET
RESET
GND
RESET
1
2
3
5
VCC
CAT825
4
MR
WDI
V
CC
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. MD-3027, Rev. B
CAT823, CAT824, CAT825
BLOCK DIAGRAM
V
CC
WDI*
LEVEL SENSE
&
TIMER
TIMEOUT
COMPARATOR
RESET
V
CC
V
CC
TOLERANCE
BIAS
+
–
DIGITAL
DELAY
V
CC
V
CC
VOLTAGE
REFERENCE
RESET*
52kΩ
MR*
LEVEL SENSE
&
DEBOUNCE
* Functions Available by Device
Device
CAT823
CAT824
CAT825
¯¯¯¯¯¯
RESET
x
x
x
RESET
x
x
¯¯¯
MR
x
x
WDI
x
x
Doc. No. MD-3027, Rev. B
2
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT823, CAT824, CAT825
ABSOLUTE MAXIMUM RATINGS
(1)
Parameters
Supply Voltage
All other pins
Input Current, V
CC
Output Current RST, ¯¯¯¯
RST
Continuous Power Dissipations (T
A
= +70ºC)
SC-70 5-lead (derate 3.1mW/ºC above +70ºC)
TSOT-23 5-lead (derate 7.1mW/ºC above +70ºC)
Storage Temperature
Operating Ambient Temperature
Lead Soldering (10 seconds max)
ESD Rating: Low Voltage Pins
Human Body Model
Machine Model
RECOMMENDED OPERATING CONDITIONS
Parameter
V
CC
(T
A
= 0ºC to +70ºC)
V
CC
(T
A
= -40ºC to +85ºC)
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
ºC
247
571
-65 to 150
-40 to +85
+300
2000
200
mW
mW
ºC
ºC
ºC
V
V
Ratings
6
-0.3 to (V
CC
+ 0.3)
20
20
Units
V
V
mA
mA
Notes:
(1) Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions outside of those listed in the operational sections of this
specification is not implied. Exposure to any absolute maximum rating for extended periods may affect device performance and reliability.
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
3
Doc. No. MD-3027, Rev. B
CAT823, CAT824, CAT825
ELECTRICAL OPERATING CHARACTERISTICS
DC Characteristics: V
CC
= 3.0V to 5.5V for L/M versions; V
CC
= 2.0V to 3.6V for the R/S/T/Y/Z version,
-40ºC
≤
T
A
≤
+85ºC unless otherwise noted. Typical Values at T
A
= 25ºC and V
CC
= 5V for L/M versions;
V
CC
= 3.3V for the T/S versions; V
CC
= 3.0V for the R version; and V
CC
= 2.5V for the Y/Z versions.
(1)
Symbol Parameter
Conditions
CAT823 (L/M Versions)
CAT824 (L/M Versions)
I
CC
Supply Current
CAT823 (R/S/T/Y/Z Versions)
CAT824 (R/S/T/Y/Z Versions)
CAT825 (L/M Versions)
CAT825 (R/S/T/Y/Z Versions)
CAT82_L at -40ºC
≤
T
A
≤
+85ºC
CAT82_M at -40ºC
≤
T
A
≤
+85ºC
CAT82_T at -40ºC
≤
T
A
≤
+85ºC
V
RST
Reset Threshold
CAT82_S at -40ºC
≤
T
A
≤
+85ºC
CAT82_R at -40ºC
≤
T
A
≤
+85ºC
CAT82_Z at -40ºC
≤
T
A
≤
+85ºC
CAT82_Y at -40ºC
≤
T
A
≤
+85ºC
Reset Threshold
Tempco
Reset Threshold
Hysteresis
t
RD
t
RP
Reset Active
Timeout Period
¯¯¯¯¯¯
RESET Output High
Voltage
CAT82_L/M, V
CC
= V
RST max
,
I
SOURCE
= -120µA
CAT82_T/S/R/Z/Y, V
CC
= V
RST max
,
I
SOURCE
= -30µA
CAT82_L/M, V
CC
= V
RST min
,
I
SINK
= 3.2mA
V
OL
¯¯¯¯¯¯
RESET Output Low
Voltage
CAT82_T/S/R/Z/Y, V
CC
= V
RST min
,
I
SINK
= 1.2mA
T
A
= 0ºC to +70ºC, V
CC
= 1V,
V
CC
falling, I
SINK
= 50µA
T
A
= T
MIN
to T
MAX
, V
CC
= 1.2V,
V
CC
falling, I
SINK
= 100µA
I
SOURCE
V
OH
V
OL
Reset Output
Voltage
CAT82_L/M, Reset = 0V, V
CC
= 5.5V
¯¯¯¯¯¯
RESET Output
Short-Circuit Current CAT82_L/M, Reset = 0V, V
CC
= 3.6V
V
CC
> 1.8V, I
SOURCE
= -150µA
CAT824L/M & CAT825L/M,
V
CC
= V
RST max
, I
SINK
= 3.2mA
CAT824R/S/T/Y/Z & CAT825R/S/T/Y/Z,
V
CC
= V
RST max
, I
SINK
= 1.2mA
0.8 x V
CC
0.4
0.3
V
CAT82_L/M
CAT82_R/S/T/Y/Z
4.50
4.25
3.00
2.85
2.55
2.25
2.13
Min
Typ
6
4
3
2
4.63
4.38
3.08
2.93
2.63
2.32
2.19
40
10
5
20
140
V
CC
- 1.5V
0.8 x V
CC
0.4
V
0.3
0.3
0.3
1.5
0.8
mA
200
400
Max
17
12
8
6
4.75
4.50
3.15
3.00
2.70
2.38
2.25
Units
µA
µA
µA
µA
V
V
V
V
V
V
V
ppm/ºC
mV
mV
µs
ms
V
CC
to Reset Delay
(2)
V
CC
= V
TH
to (V
TH
- 100mV)
V
OH
Notes:
(1) Over-temperature limits are guaranteed by design and not production tested.
(2)
The RESET short-circuit current is the maximum pull-up current when reset is driven low by a bidirectional output.
4
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
Doc. No. MD-3027 Rev. B
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