188 V rail clamp — what the ratings mean
The SMBJ188A-TR is a unidirectional TRANSIL™ TVS diode from STMicroelectronics designed to protect a 188 V DC rail from transient overvoltage events. Its 209 V minimum breakdown voltage ensures the device starts clamping before the protected circuitry sees damaging voltage, while the 328 V maximum clamping limits the peak voltage seen by the load during a 2 A, 10/1000 µs surge.
Obsolete — sourcing path for this BOM line
No official successor part is listed by ST, so a pin-compatible replacement within the SMBJ family (same DO-214AA footprint, same 188 V standoff) would need to be qualified against the original's clamping and pulse-power specs.