Two-voltage supervisor for automotive and industrial rails
The Texas Instruments TPS3306-25QDRG4Q1 is a multi-voltage supervisor that monitors two independent supply rails with thresholds of 2.25V and 2.93V. It asserts an active-low, open-drain reset when either voltage falls below its threshold, and holds reset for a minimum of 70ms after both rails recover.
The 2.25V threshold is sized for a 2.5V or 3.3V rail with margin; the 2.93V threshold suits a 3.3V rail with tighter supervision. The 70ms minimum reset timeout ensures the downstream processor or FPGA completes a full power-on reset cycle before the supervisor releases the reset line, preventing spurious boot-up on a rail that has not fully settled. An open-drain output allows the reset signal to be wire-ORed with other supervisors or a manual reset button, and the pull-up resistor can be tied to a different voltage than the monitored rails. This flexibility is useful in mixed-voltage systems where the reset signal must be valid before the processor supply has ramped.