Two-Rail Window Supervisor for Automotive Power Sequencing
The TPS37042A3OFDDFRQ1 is a Texas Instruments automotive-grade multi-voltage supervisor that monitors two independent supply rails — 1.2 V and 3.3 V — and asserts an active-low, open-drain reset when either rail falls outside its window. The reset timeout is 10 ms typical — long enough to let the downstream MCU finish its internal reset sequence without adding unnecessary delay to the power-up cycle.
Threshold Selection and Reset Architecture
Fixed thresholds at 1.2 V and 3.3 V eliminate external resistor dividers — the supervisor directly connects to the monitored rails with only a decoupling capacitor per datasheet recommendation. The open-drain output allows wired-OR connection with other supervisors or a pull-up to the MCU supply voltage, simplifying reset distribution across multiple voltage domains. Compared to simple single-rail reset ICs like the TLV803EA29VDBZR (which monitors a single rail with a 130 ms minimum timeout), the TPS37042 brings two-rail window monitoring in a single SOT-23-8 package, saving board space and component count.
Texas Instruments continues to manufacture this part for automotive programs requiring long-life support. The base product number is TPS37042; the full suffix A3OFDDFRQ1 specifies the threshold variant and package option. No stock-holding claim — sourced to order through our distribution channel.