TPS3813J25 Datasheet, PDF (1/12 Pages) Texas Instruments – PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG

TPS3813J25, TPS3813L30, TPS3813K33, TPS3813I50
PROCESSOR SUPERVISORY CIRCUITS WITH WINDOW-WATCHDOG
SLVS331A – DECEMBER 2000 – REVISED APRIL 2001
features
typical applications
D Window-Watchdog With Programmable
Delay and Window Ratio
D 6-Pin SOT-23 Package
D Supply Current of 9 µA (Typ)
D Power On Reset Generator With a Fixed
Delay Time of 25 ms
D Precision Supply Voltage Monitor 2.5 V, 3 V,
3.3 V, 5 V
D Open-Drain Reset Output
D Temperature Range . . . –40°C to 85°C
D Applications Using DSPs, Microcontrollers,
or Microprocessors
D Safety Critical Systems
D Automotive Systems
D Heating Systems
TPS3813
DBV PACKAGE
(TOP VIEW)
WDI 1
6
RESET
GND 2
5
WDR
description
WDT ³
4
VDD
The TPS3813 family of supervisory circuits pro-
vides circuit initialization and timing supervision,
primarily for DSPs and processor-based systems.
ACTUAL SIZE
During power on, RESET is asserted when supply
3,00 mm x 3,00 mm
voltage (V_DD) becomes higher than 1.1 V. There
after, the supervisory circuit monitors V_DD and keeps RESET active as long as V_DD remains below the threshold
voltage (V_IT). An internal timer delays the return of the output to the inactive state (high) to ensure proper system
reset. The delay time, t_d = 25 ms typical, starts after V_DD has risen above the threshold voltage (V_IT). When the
supply voltage drops below the threshold voltage (V_IT), the output becomes active (low) again. No external
components are required. All the devices of this family have a fixed-sense threshold voltage (V_IT) set by an
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_DD, or using an external capacitor. The lower limit and thus the window ratio is set by connecting
WDR to GND or V_DD. The supervised processor now needs to trigger the TPS3813 within this window not to
assert a RESET.
typical operating circuit
VDD
CWP
0.1 µF
R
VDD
WDR RESET
TPS3813
WDT
WDI
GND
VDD
RESET
uC
I/O
GND
0.1 µF
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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.
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Copyright  2001, Texas Instruments Incorporated
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