What this reset supervisor does on your board
The TPS3820-33DBVTG4 is a single-channel voltage supervisor from Texas Instruments that monitors a 3.3V rail and holds the microcontroller in reset until the supply settles. It asserts a logic-low reset output when VDD drops below 2.93V and keeps it low for a minimum of 15 ms after the supply recovers — enough time for most MCU oscillators and PLLs to stabilise before code execution starts. The output is active low, so it connects directly to the /RESET pin of a typical ARM Cortex-M or PIC microcontroller.
2.93V threshold — the 3.3V rail watchdog
The 2.93V reset threshold is set for a nominal 3.3V supply. When the rail droops below that level — from a brownout, a transient load step, or a failing regulator — the supervisor pulls reset low before the MCU can glitch into an undefined state. The 15 ms timeout gives the supply time to recover and the oscillator to stabilise before the processor starts fetching code. This is a single-voltage monitor — it watches one rail. If your design needs supervision on multiple supplies (e.g., 1.8V core and 3.3V I/O), you would need a multi-channel supervisor or a second instance of this part.
SOT-23-5 package — field-swap friendly
The SOT-23-5 package (SC-74A, SOT-753) is a five-pin surface-mount package with a 0.95 mm pitch. The pinout is straightforward: GND, RESET, VDD, and two no-connect pins. Not rated for under-hood or downhole, but fine for most PCB-level supervisory duties.
No end-of-life notice, no last-time-buy deadline. The base product number is TPS3820; the suffix -33DBVTG4 indicates the 2.93V threshold variant in SOT-23-5 on tape and reel.