TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50
PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG
SLVS331A – DECEMBER 2000 – REVISED APRIL 2001
features
typical applications
Window-Watchdog With Programmable
Delay and Window Ratio
Applications Using DSPs, Microcontrollers,
or Microprocessors
6-Pin SOT-23 Package
Safety Critical Systems
Automotive Systems
Heating Systems
Supply Current of 9 µA (Typ)
Power On Reset Generator With a Fixed
Delay Time of 25 ms
TPS3813
DBV PACKAGE
(TOP VIEW)
Precision Supply Voltage Monitor 2.5 V, 3 V,
3.3 V, 5 V
1
2
3
6
5
4
RESET
WDR
Open-Drain Reset Output
WDI
Temperature Range . . . –40°C to 85°C
GND
description
V
DD
WDT
The TPS3813 family of supervisory circuits pro-
vides circuit initialization and timing supervision,
primarily for DSPs and processor-based systems.
ACTUAL SIZE
3,00 mm x 3,00 mm
During power on, RESET is asserted when supply
voltage (V ) becomes higher than 1.1 V. There
DD
after, the supervisory circuit monitors V and keeps RESET active as long as V remains below the threshold
DD
DD
voltage (V ). An internal timer delays the return of the output to the inactive state (high) to ensure proper system
IT
reset. The delay time, t = 25 ms typical, starts after V has risen above the threshold voltage (V ). When the
DD
IT
d
supply voltage drops below the threshold voltage (V ), the output becomes active (low) again. No external
IT
components are required. All the devices of this family have a fixed-sense threshold voltage (V ) set by an
IT
internal voltage divider.
For safety critical applications the TPS3813 family incorporates a so-called window-watchdog with
programmable delay and window ratio. The upper limit of the watchdog time-out can be set by either connecting
WDT to GND, V , or using an external capacitor. The lower limit and thus the window ratio is set by connecting
DD
WDR to GND or V . The supervised processor now needs to trigger the TPS3813 within this window not to
DD
assert a RESET.
typical operating circuit
V
DD
0.1 µF
0.1 µF
R
V
DD
V
DD
WDR RESET
TPS3813
RESET
uC
WDT
WDI
I/O
GND
GND
C
WP
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright 2001, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
1
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