What this reset IC does on the board
The TPS3126E15DBVR: The threshold is set at 1.43V, so it tracks a 1.5V or 1.8V core rail — the kind that powers a low-voltage MCU, FPGA, or DSP core. The reset output is active low, open-drain, which means it pulls the reset line low when the monitored voltage drops below threshold. You need an external pull-up resistor to Vcc of the processor — typically 10kΩ to 100kΩ. The open-drain topology lets multiple reset sources share the same line.
Threshold voltage — the fit decision
The 1.43V threshold is the single number that decides whether this part fits your rail. It triggers at roughly 1.43V, so it is designed for a nominal 1.5V or 1.8V supply. The part monitors one voltage only — no second channel for an I/O rail. If your design needs supervision on two independent supplies, you need two of these or a multi-voltage supervisor.
Housed in a SOT-23-5 (SC-74A) package, this is a five-pin surface-mount part with 0.95mm pitch. The small footprint fits tight layouts on 2-layer boards.