The TPS312x family of supervisors provide circuit initialization and timing supervision. Optional configurations include devices with active-high and active-low output signals (TPS3124/3125/3126), devices with a watchdog timer (TPS3123/3124/3128), and devices with manual reset (MR) pins (TPS3123/3125/3126/3128). RESET output is valid when the supply voltage, V_DD, is above 0.75 V. For devices with active-low output logic, the device monitors V_DD and keeps RESET low as long as V_DD remains below the negative threshold voltage, V_IT−. For devices with active-high output logic, RESET remains high as long as V_DD remains below 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, starts after V_DD rises above the positive threshold voltage (V_IT− + V_HYS). When the supply voltage drops below
V_IT−, the output becomes active (low) again. All the devices of this family have a fixed-sense threshold voltage,
V_IT–, set by an internal voltage divider, so no external components are required.

The TPS312x family is designed to monitor voltages listed on Table 9-2. For devices with the manual reset functionality, a low level at MR causes RESET to become active. For devices with the watch dog timer functionality, when the supervising system fails to retrigger the watchdog circuit within the time-out interval t_tout = 0.8 s, RESET output becomes active for the time period (t_d). This event also reinitializes the watchdog timer. The devices are available in a 5-pin SOT-23 package and are characterized for operation over a temperature range of −40°C to 85°C.