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CAT1832 Schematic ( PDF Datasheet ) - Catalyst Semiconductor

Teilenummer CAT1832
Beschreibung (CAT1232LP / CAT1832) 5V AND 3.3V SUPPLY VOLTAGE MONITOR AND RESET CIRCUIT
Hersteller Catalyst Semiconductor
Logo Catalyst Semiconductor Logo 




Gesamt 12 Seiten
CAT1832 Datasheet, Funktion
CAT1232LP/CAT1832
5V and 3.3V Supply Monitor, Watchdog Timer,
Manual Reset, with Active High & Low Resets
FEATURES
DESCRIPTION
s Selectable reset voltage tolerance
— CAT1232LP for 5V supply
— CAT1832 for 3.3V supply
s Selectable watchdog period:
150ms, 600ms or 1.2 sec
s Two reset outputs
The CAT1232LP and CAT1832 microprocessor
supervisors can halt and restart a “hung-up” or “stalled”
microprocessor, restart a microprocessor after a power
failure, and debounce a manual/push-button micro-
processor reset switch. The devices are drop in
replacements for the Maxim/Dallas Semiconductor
DS1232LP and DS1832 supervisors
— Active high, push-pull reset output
— Active low, open-drain reset output
(CAT1232LP)
— Active low, push-pull reset output (CAT1832)
Precision reference and comparator circuits monitor the
5V or 3.3V system power supply voltage, VCC. During
power-up or when the power supply falls outside
selectable tolerance limits, both the RESET and RESET
become active. After the power supply voltage rises
s Debounced manual push-button reset
s Compact SOIC and MSOP packages
above the RESET threshold voltage, the reset signals
remain active for a minimum of 250ms, allowing the
power supply and system processor to stabilize. The
trip-point tolerance input, TOL, selects the trip level
APPLICATIONS
tolerance to be either 5% or 10% for the CAT1232LP 5V
supply and 10% or 20% for the CAT1832 3.3V supply.
s Microprocessor Systems
s Portable Equipment
Each device has a push-pull, active HIGH reset output.
Thewww.DataSheet4U.com CAT1232LP also has an open drain, active LOW
s Controllers
s Single Board Computers
reset output while the CAT1832 also has a push-pull,
active LOW reset output.
s Instrumentations
s Telecommunications
A debounced manual reset input activates the reset
outputs and holds them active for a minimum period of
250ms after being released.
For Ordering Information details, see page 11.
Also included is a watchdog timer to reset a
microprocessor that has stopped due to a software or
hardware failure. Three watchdog time-out periods are
selectable: 150ms, 600ms and 1.2sec. If the ST input is
not strobed low before the watchdog time out period
expires, the reset signals become active for a minimum
of 250ms.
FUNCTIONAL DIAGRAM
VCC
TOL
PBRST
TD
ST
VCC
40k
Tolerance Selection
Reference
+
Push Button Debounce
Watchdog Timebase Selection
Watchdog Transition Detector
Reset &
Watchdog Timer
(CAT1232LP)
RESET
RESET
RESET
(CAT1832)
© 2006 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. 25089, Rev. 0C






CAT1832 Datasheet, Funktion
CAT1232LP/CAT1832
WATCHDOG TIMER AND ST INPUT
A watchdog timer stops and restarts a microprocessor
that has stopped proper operation or become hung.
The watchdog performs this function by monitoring the
ST input. After the reset outputs go inactive the ST input
must be strobed with a high-to-low signal transition prior
to the minimum watchdog timeout period. However if the
ST input is not strobed with a high-to-low signal transi-
tion prior to a watchdog timeout the reset outputs will
become active for TRST reseting and restarting the
microprocessor. Once the resets return to the inactive
state the watchdog timer restarts the process.
The TD input allows the user to select from three
predetermined watchdog timeout periods. Always use
the minimum timeout period to determine the required
frequency of ST high-to-low transitions and the maxi-
mum to determine the time prior to the reset outputs
becoming active. ST pulse widths must be 20ns or
greater.
The watchdog timer cannot be disabled. It must be
strobed with a high-to-low signal transition to avoid a
watchdog timeout and subsequent reset.
TD Voltage
Level
GND
Floating
VCC
Watchdog Time-out Period (ms)
MIN NOMINAL MAX
62.5 150 250
250 600 1000
500
1200
2000
CAT1832
3.3V
1
PBRST
2
TD
8
VCC
7
ST
36
TOL RESET
45
GND RESET
I/O
µP
RESET
Figure 4. CAT1832 Application Circuit:
Pushbutton Reset
CAT1232LP
5V
1
PBRST
2
TD
8
VCC
7
ST
36
TOL RESET
45
GND RESET
10k
µP
RESET
MREQ
Address
Bus
Decoder
Figure 5. CAT1232LP Application Circuit: Watchdog Timer
PBRST
RESET
RESET
tPB
tPDLY
VIL
VIH
tRST
VOH
VOL
Figure 6. Timing Diagram: Pushbutton Reset
Valid
Valid
Strobe
Strobe
ST
RESET
RESET
tRST
tST
tTD
(Min)
tTD
(Min)
Note:ST is ignored whenever a reset is active.
Invalid
Strobe
Figure 7. Timing Diagram: Strobe Input
Doc. No. 25089, Rev. 0C
6
© 2006 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice

6 Page









CAT1832 pdf, datenblatt
REVISION HISTORY
Date
06/13/2005
07/26/2005
03/27/2006
08/21/2006
Revision Comments
00 Initial Issue
0A Update Electrical Characteristics
Add Typical Characteristics
0B Update Document Title
Update Ordering Information
0C Add Ordering Information detail to page 1
Update Sample of Ordering Information
Copyrights, Trademarks and Patents
Trademarks and registered trademarks of Catalyst Semiconductor include each of the following:
DPP ™ AE2
Catalyst Semiconductor has been issued U.S. and foreign patents and has patent applications pending that protect its products.
CATALYST SEMICONDUCTOR MAKES NO WARRANTY, REPRESENTATION OR GUARANTEE, EXPRESS OR IMPLIED, REGARDING THE SUITABILITY OF ITS
PRODUCTS FOR ANY PARTICULAR PURPOSE, NOR THAT THE USE OF ITS PRODUCTS WILL NOT INFRINGE ITS INTELLECTUAL PROPERTY RIGHTS OR THE
RIGHTS OF THIRD PARTIES WITH RESPECT TO ANY PARTICULAR USE OR APPLICATION AND SPECIFICALLY DISCLAIMS ANY AND ALL LIABILITY ARISING
OUT OF ANY SUCH USE OR APPLICATION, INCLUDING BUT NOT LIMITED TO, CONSEQUENTIAL OR INCIDENTAL DAMAGES.
Catalyst Semiconductor products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or
other applications intended to support or sustain life, or for any other application in which the failure of the Catalyst Semiconductor product could create a
situation where personal injury or death may occur.
Catalyst Semiconductor reserves the right to make changes to or discontinue any product or service described herein without notice. Products with data sheets
labeled "Advance Information" or "Preliminary" and other products described herein may not be in production or offered for sale.
Catalyst Semiconductor advises customers to obtain the current version of the relevant product information before placing orders. Circuit diagrams illustrate
typical semiconductor applications and may not be complete.
Catalyst Semiconductor, Inc.
Corporate Headquarters
2975 Stender Way
Santa Clara, CA 95054
Phone: 408.542.1000
Fax: 408.542.1200
www.catsemi.com
Publication #: 25089
Revison:
0C
Issue date: 08/21/06

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