Battery Backup Supervisor for 5V Rails
The TPS3617-50DGKG4 is a Battery Backup Circuit supervisor from Texas Instruments, designed to monitor a single 5V supply rail with a 4.55V threshold. It asserts an active-low reset output (push-pull, totem pole) when the monitored voltage drops below threshold, and holds reset for a minimum of 60ms after the supply returns.
Threshold and Reset Timing
The 4.55V threshold is a precision trip point for a nominal 5V supply — it triggers before the rail drops to an unreliable level for logic or memory, giving the backup battery time to take over. The 60ms minimum reset timeout ensures the micro or memory has fully settled before release, preventing brownout glitches on power-up. With an active-low, push-pull output, the reset signal drives directly into the enable or reset pin of an MCU, FPGA, or RTC without needing an external pull-up resistor. The push-pull stage sinks and sources current cleanly, which simplifies the BOM on the supervisor interface.
The small footprint leaves board space for the backup battery and its charging circuit.