What the 3.7V threshold means for your 3.3V rail
The TPS3840DL37DBVRQ1 monitors a single voltage rail and asserts a reset when the supply drops below 3.7V. For a 3.3V nominal rail, that threshold sits at roughly 12% above the target — the supervisor triggers before the rail collapses below the minimum operating voltage of most 3.3V logic, giving the system a clean reset edge. The active-low open-drain output pulls the reset line low on a fault and releases it after the 619 ms typical reset timeout once the rail recovers. That 619 ms window is long enough to let a downstream regulator or oscillator stabilize before the processor starts executing. The part is a Simple Reset/Power-On Reset type — no adjustable delay, no manual reset input. It is a fixed-threshold, fixed-timeout supervisor for applications where the reset timing is defined by the rail behavior, not by a host controller.
Automotive grade and temperature range — where it survives
That covers under-hood electronics, engine-bay sensors, and industrial enclosures.
Package and footprint — SOT-23-5 fit check
The part is supplied in a SOT-753 package, also listed as SOT-23-5 supplier device package. The 5-pin SOT-23 footprint is a de facto standard for voltage supervisors — the same land pattern handles the TLV803 and many other reset ICs, so a board respin is unlikely if swapping between these families. Available in Tape & Reel and Cut Tape options for both production reels and prototype quantities.
Sourcing through authorized distribution is straightforward — no date-code lottery or broker-mystery stock required. ROHS3 compliant, which matches the current EU exemption rules. No transition risk from an older ROHS version.
How it compares to the TLV803 family
The closest functional second-source candidate is the TLV803EA29VDBZR — also an active-low, open-drain simple reset IC in a similar SOT-23 package. The key difference is the threshold: the TLV803EA29VDBZR trips at 2.93V, not 3.7V. If your rail is 3.3V, the TPS3840DL37DBVRQ1 gives a higher guard band. The TLV803EA29VDBZR has a 130 ms minimum reset timeout versus the 619 ms typical on the TPS3840 — so the TPS3840 holds the processor in reset longer after a brown-out. The TLV803ED29DBZR is another sibling with a 33 ms minimum reset timeout — even shorter. For systems that need a fast restart after a glitch, that might be the better fit, but the TPS3840DL37DBVRQ1's 619 ms timeout is more forgiving for power supplies with slow ramp-up.