The TPS3306 family is a series of supervisory circuits
designed for circuit initialization which require two supply voltages,
primarily in DSP and processor-based systems.
The product spectrum of the TPS3306-xx is designed for monitoring two independent supply voltages of 3.3 V/1.5 V, 3.3 V/1.8 V, 3.3 V/2 V, 3.3 V/2.5 V, or 3.3 V/5 V.
The various supervisory circuits are designed to monitor the nominal supply voltage.
During power-on, RESET
is asserted when the supply voltage VDD
becomes higher than 1.1 V. Thereafter, the supervisory circuits monitor the
SENSEn inputs and keep RESET active as
long as SENSEn remains below the threshold voltage VIT.
An internal timer delays the return of the
RESET output to the inactive state (high)
to ensure proper system reset. The delay time, td(typ) = 100 ms, starts after SENSE1 and
SENSE2 inputs have risen above the threshold voltage VIT. When the voltage at SENSE1 or SENSE2 input drops
below the threshold voltage VIT, the
output becomes active (low) again.
The integrated power-fail (PFI) comparator with separate
open-drain (PFO) output can be used for
low-battery detection, power-fail warning, or for monitoring a power supply
other than the main supply.
The TPS3306-xx devices integrate a watchdog timer that is
periodically triggered by a positive or negative transition of WDI. When the
supervising system fails to retrigger the watchdog circuit within the time-out
interval, tt(out) = 0.50 s,
RESET becomes active for the time period
td. This event also reinitializes the
watchdog timer. Leaving WDI unconnected disables the watchdog.
The TPS3306-xx devices are available in either 8-pin MSOP
or standard 8-pin SO packages, and are characterized for operation over a
temperature range of -40°C to +85°C.