tps3705-30.pdf
Features
Power-On Reset Generator with Fixed
Delay Time of 200 ms, no External
Capacitor Needed
Precision Supply Voltage Monitor 2.5 V, 3 V,
3.3 V, and 5 V
Pin-For-Pin Compatible with the MAX705
through MAX708 Series
Integrated Watchdog Timer (TPS3705 only)
Voltage Monitor for Power-Fail or
Low-Battery Warning
Maximum Supply Current of 50 μA
MSOP-8 and SO-8 Packages
Temperature Range . . . −40°C to 85°C
typical applications
Designs Using DSPs, Microcontrollers or
Microprocessors
Industrial Equipment
Programmable Controls
Automotive Systems
Portable/Battery Powered Equipment
Intelligent Instruments
Wireless Communication Systems
Notebook/Desktop Computers
description
The TPS3705, TPS3707 family of microprocessor supply-voltage supervisors provide circuit initialization and
timing supervision, primarily for DSP and processor-based systems.
During power-on, RESET is asserted when the supply voltage VDD becomes higher than 1.1 V. Thereafter, the
supply voltage supervisor monitors VDD and keeps RESET active as long as VDD remains below the threshold
voltage VIT+. An internal timer delays the return of the output to the inactive state (high) to ensure proper system
reset. The delay time, tdtyp= 200 ms, starts after VDDhas risen above the threshold voltage VIT+. When the supply
voltage drops below the threshold voltage VIT– , the output becomes active (low) again. No external components
are required. All the devices of this family have a fixed-sense threshold voltage VIT– set by an internal voltage
divider.
The TPS3705-xx and TPS3707-xx devices incorporate a manual reset input, MR. A low level at MR causes
RESET to become active.
The TPS370x-xx families integrate a power-fail comparator which can be used for low-battery detection,
power-fail warning, or for monitoring a power supply other than the main supply.
The TPS3705-xx devices have a watchdog timer that is periodically triggered by a positive or negative transition
at WDI. When the supervising system fails to retrigger the watchdog circuit within the time-out interval,
tt(out) = 1.6 s, WDO becomes active. This event also reinitializes the watchdog timer. Leaving WDI unconnected
disables the watchdog.
The TPS3707-xx devices do not have the Watchdog function, but include a high-level output RESET.
The product spectrum is designed for supply voltages of 2.5 V, 3 V, 3.3 V, and 5 V. The circuits are available in
either 8-pin MSOP or standard SOIC packages. The TPS3705, TPS3707 devices are characterized for
operation over a temperature range of −40°C to 85°C.
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DatasheetDoc-Texas Instruments TI pdf datasheet download
