What is this component? When I search on internet, I get a lot of thermal protection components, but they do not look like this.
I got it as a batch from someone, so I don't know the usage.
The dimensions are 7.5 mm x 5.7mm, it has two legs (one on the other side), which extend to the bottom (thus it must be an SMD component).
(sorry for the white spots, the camera lens was dirty).
The "LF" means a Littelfuse Part. The casing is SMC, meaning it is likely a Transient Voltage Suppressor (TVS). They make an SMC part with the number SMCJ120CA, which seems like a safe bet as to what this is. The 120C is a bidirectional 120V part.
The job of this part is to limit the voltage on the line it is connected to. In normal operation, it does not conduct, but above a certain threshold, it turns on, effectively clamping the voltage between the terminals like a diode. In this case, it is meant to connect to a line that is nominally between +/- 120V, starts conducting at +/- 133, and will limit its voltage to +/- 193V. Usually the other terminal is ground, but you can also find them providing differential protection, like between cells of a battery charger.
These are typically found near connectors to prevent electrical nastiness from going inside your board and burning something sensitive.
