Three-rail supervisor with military temp range
The TPS3307-33MDGNREP is a three-channel multi-voltage supervisor from Texas Instruments, monitoring up to three supply rails with thresholds at 2.93V, 4.55V, and one adjustable input. This part is designed for systems that require sequenced or independent monitoring of multiple voltages — common in DSP, FPGA, and processor core + I/O rail combinations. Both active-high and active-low reset outputs are provided, giving the designer flexibility to interface with different reset logic families without external inversion. The push-pull output stage eliminates the need for a pull-up resistor, saving a component per channel.
Thresholds and timeout for rail sequencing
The fixed thresholds — 2.93V for a 3.3V rail and 4.55V for a 5V rail — are set at typical undervoltage levels, so the supervisor asserts reset before the monitored rail drops out of spec. The adjustable input lets you set a third threshold with an external resistor divider, covering intermediate rails like 1.8V or 2.5V. This prevents premature processor release during supply ramp transients.