Transient suppression for a 120V rail — what the ratings mean
Its 133V minimum breakdown voltage means the device starts conducting just above the normal operating voltage, and the 193V maximum clamping voltage at 3.1A peak pulse current defines the survival voltage the downstream components must withstand.
Package and temperature range for the board
Microchip lists the SMBJ120AE3/TR13 as Active, so there is no looming obsolescence or last-time-buy pressure. The base product number SMBJ120 is a mature, widely used TVS family; second-source equivalents exist from other major brands, but the Microchip suffix indicates a specific lead-free finish and test flow.