A　novel　duty-cycle-sensing　overload　detector　for　DC-DC　converter　is　proposed　in　this　paper.　Firstly,　the　theoretical　analysis　is　conducted　to　reveal　the　susceptibility　of　the　conventional　overload　detectors　to　temperature　variation　and　the　input/output-voltage　change　of　the　DC-DC　converter.　Then,　the　schematic　of　the　novel　duty-cycle-sensing　overload　detector　is　presented　and　its　operation　principle　is　analyzed.　Thanks　to　the　time　register,　the　proposed　detector　generates　a　theoretically　voltage-and-temperature-insensitive　threshold　duty　cycle,　compares　it　with　the　real-time　duty　cycle　of　the　converter＇s　PWM　signal,　and　announces　an　overload　event　if　the　real-time　duty　cycle　exceeds　the　threshold.　Finally,　a　prototype　of　a　BUCK　DC-DC　converter　including　the　proposed　detector　and　a　conventional　current-sensing　overload　detector　is　constructed　and　measured.　As　the　measurement　results　show,　the　threshold　duty　cycle　only　varies　by　about　2.4%　as　the　temperature　changes　from　0　to　90　°C　while　the　threshold　voltage　of　the　conventional　current-sensing　detector　changes　by　about　4.6%.　The　proposed　detector　can　keep　effective　even　the　temperature　rises　to　90　°C　while　the　conventional　current-sensing　detector　can　work　at　a　temperature　no　higher　than　85　°C.　Without　circuitry　modification,　the　proposed　detector　correctly　senses　the　overload　event　as　the　DC-DC　converter＇s　output　voltage　changes　in　a　range　of　2.1–2.9 V　while　the　conventional　one　loses　its　effectiveness　if　the　output　voltage　is　set　higher　than　2.54　V.　©　2023　Institute　of　Electrical　Engineers　of　Japan.　Published　by　Wiley　Periodicals　LLC.　©　2023　Institute　of　Electrical　Engineers　of　Japan.　Published　by　Wiley　Periodicals　LLC.