4.5V supply monitor with a 619ms hold-off
The TPS3840PL45DBVR is a single-channel power supply monitor from Texas Instruments that asserts an active-low reset when the monitored rail drops below 4.5V. The reset output stays low for 619ms typical after the supply recovers — long enough for most MCUs and SoCs to complete their power-on reset sequence before the core starts executing code. The push-pull output drives the reset line directly without an external pull-up resistor, saving a BOM component on boards where the MCU reset pin is not internally pulled high.
Wide temperature range and package fit
Housed in a 5-pin SOT-23 (SC-74A) package, it shares the same 0.95 mm pitch footprint as many other TI supervisors — the TLV803 family, for example — so a layout designed for one can often accept the other with a BOM swap.
Active production — no end-of-life shadow
The base product number TPS3840 covers multiple voltage thresholds in the same package — if a future design moves to a 3.3V or 5.0V rail, the PCB layout stays unchanged.