Battery backup supervisor for 5 V rails
The Texas Instruments TPS3617-50DGKR is a battery backup supervisor IC that monitors a single 5 V supply and switches to a backup battery when the main rail drops below the 4.55 V threshold. Its active-low, push-pull reset output holds the target device in reset for a minimum of 60 ms after the supply returns above the threshold, giving the system time to stabilise. Typical applications include SRAM backup, RTC hold-up, and microcontroller power-fail detection in industrial and telecom equipment where a clean reset and seamless battery switchover are required.
The 4.55 V threshold is set for a nominal 5 V rail with a typical tolerance of ±10 %. A supervisor with a lower threshold (e.g., 4.40 V) would allow the rail to droop further before asserting reset, which may be acceptable for some 5 V logic but risks data corruption in SRAM backup scenarios. The 60 ms minimum reset timeout is long enough to cover most power-supply ramp-up and oscillator start-up delays, but if the system uses a large output capacitor on the 5 V rail, verify that the timeout does not expire before the rail is fully settled — a supervisor with a longer timeout may be needed.