3.3V rail supervisor with 619 ms timeout
The TPS3840PL33DBVR is a nanopower Simple Reset/Power-On Reset IC from Texas Instruments, designed to monitor a single 3.3V supply rail and assert a reset signal when the voltage drops below the threshold. The reset output is Active Low with a push-pull, totem pole stage, meaning it drives the reset line low during undervoltage and releases it high when the supply recovers, with no external pull-up resistor needed. A typical reset timeout of 619 ms holds the reset line low after the supply stabilises, giving the downstream MCU or SoC time to complete its power-on sequence before code execution starts.
Housed in a SOT-23-5 (SC-74A) package, it occupies minimal board area and routes easily on a 2-layer PCB — the 5-pin footprint keeps the fan-out simple for the supply and reset traces.