The SMFJ40A is a surface-mount transistor-voltage suppressor with 64.5V, 44.4V, and 40V working voltage levels, produced by Bourne. It is a type of transient voltage suppressor (TVS) with a SOD-123FL package, and is RoHS compliant. It is designed to provide protection against electrical transients and to suppress peaks of very high voltage. It can be used in a variety of applications, including computers, telecommunications devices, mobile phones, and automotive electronics.