The SMBJ28A is a 28V unidirectional TVS diode from Littelfuse Inc. It offers 45.4V clamping voltage and 600W peak pulse power dissipation in a surface mount DO-214AA (SMB) package.
SMBJ28A-HR is a 600W unidirectional TVS diode from Littelfuse with 28V reverse standoff voltage and 45.4V clamping voltage. It comes in a surface-mount DO-214AA (SMB) package.