The TPS3809 family of supervisory circuits provides circuit initialization and timing supervision, primarily for DSPs and processor-based systems.
During power-on, RESET is asserted when the supply voltage VDD becomes higher than 1.1 V. Thereafter, the supervisory circuit 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, td(typ) = 200 ms, starts after VDD has 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 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 3-pin SOT-23. The TPS3809 devices are characterized for operation over a temperature range of –40°C to 85°C.