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The TPS3813 family of supervisory circuits provides circuit initialization and timing supervision, primarily for DSPs and processor-based systems.

During power on, RESET is asserted when supply voltage (V_DD) becomes higher than 1.1 V. Thereafter, 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.

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 a 6-pin SOT-23 package.

The TPS3813 devices are characterized for operation over a temperature range of -55°C to 125°C.