The TPS3306-33DGK monitors two supply rails simultaneously with thresholds at 2.93 V and 4.55 V — a common pairing for systems running both a 3.3 V core and a 5 V peripheral or I/O rail. If either rail dips below its threshold, the open-drain active-low reset output pulls low and holds for a minimum of 70 ms after both rails recover. That 70 ms window gives the processor time to finish its oscillator startup and register initialization before the reset de-asserts.
Threshold selection and timing margin
The 2.93 V threshold on the first channel is set for a nominal 3.3 V rail — it trips at roughly 89 % of nominal, which is typical for supervisor ICs monitoring a 3.3 V supply. The 4.55 V threshold on the second channel corresponds to a 5 V rail, tripping at about 91 % of nominal. The 70 ms minimum reset timeout is long enough to cover most crystal oscillators and PLL lock times but short enough that the system does not sit idle for an entire power-up cycle. Compare with the TLV803EA29VDBZR, which offers a 130 ms minimum timeout at a single 2.93 V threshold — the TPS3306-33DGK adds a second channel for the 5 V rail at the cost of a slightly shorter timeout.
The 8-VSSOP package (also described as 8-TSSOP / 8-MSOP) is a standard, widely sourced footprint.