A trim circuit for an e-fuse unit includes: a mirroring circuit for receiving an enable signal, when triggered by the enable signal, the mirroring circuit generating a driving voltage; and a driving transistor coupled to the mirroring circuit, in response to the driving voltage from the mirroring circuit, the driving transistor turning ON to generate a MOS current to an output node, wherein the output node is coupled to the e-fuse unit, and in response to the MOS current from the output node, the e-fuse unit is burned out.