# How can I protect LDO NCP1117 from overheating due to short at output?

I use NCP1117 to supply voltage to various chips, such as the STM32 and buffer driver, voltage sensor, digital insulator ect. But if any of these chips fail, the LDO will heat up. What should I do?

This Circuit diagram is taken from the datasheet.
Can I use this circuit? What values are R1 and R2? 100R?

• So. You are worried about heating and other chips failing, with regards to this voltage regulator topology, and yet you have to ask what $R_1$ and $R_2$ do here? I think you are grasping way out of your reach. You need to pull back and learn a few basics before worrying about tertiary problems. You need to be able to solve the primary problems, first. Start with trying to understand how this regulator works in the optimal situation where disasters don't yet surround it. Just some well-meant advice. – jonk Nov 8 '19 at 5:15
• Sorry I'm a noob engineer – void non Nov 8 '19 at 5:32
• Don't apologize. We all start at zero. Every single one of us. I'm just suggesting that you are worrying about things you aren't yet ready for. Before you can go there, you need to take much smaller steps. In this case, you might redo the question and simply ask "What does $R_1$ and $R_2$ do in this circuit?" Or else, actually, search the questions and answers here as there is very likely already some good answers about that. I just can't see trying to answer your question about coping with part failures when you don't follow the basics of the circuit at question, yet. Cart before horse. – jonk Nov 8 '19 at 5:38
• To find what R1 and R2 do, you need to study the datasheet for the NCP1117LP voltage regulator - first step in understanding how any IC operates is to study the datasheet. Datasheets for most parts are available on-line. In this case, search for "NCP1117 datasheet". Try to find the manufacturer's website, rather the third-party sites. – Peter Bennett Nov 8 '19 at 6:32
• But if any of these chips fail, the LDO will heat up. You're worrying about an issue that isn't really an issue! Yes all components can fail. The way they fail is unpredictable. ICs failing and shorting their supply is very rare. We (designers) usually don't even think about that happening. Also yes the regulator will get hot when overloaded. However, it will survive as it will limit how hot it gets. It will not allow itself to get too hot! The best thing you can do is to add a FUSE in series with the regulator input. When too much current flows, the fuse will blow. – Bimpelrekkie Nov 8 '19 at 8:42