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 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(typ) = 200 ms, 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.