The STTH20LCD06CG-TR from STMicroelectronics is a 600 V, 10 A per diode fast-recovery rectifier in a common-cathode dual-diode configuration. The 50 ns reverse recovery time (trr) places it in the ultrafast class, suited for hard-switching topologies where reverse-recovery losses and EMI matter — boost PFC stages, output rectification in 400 V bus converters, and interleaved or center-tapped secondary windings.
ST lists the STTH20LCD06CG-TR as Obsolete. No last-time-buy window is open from the factory, and no direct successor is published in the lifecycle record. This part is not available through franchised distribution as a current-production line. Sourcing now runs through independent channels — brokers, excess inventory holders, and surplus stockists. The risk of counterfeit or relabeled parts rises when a device enters this phase, so traceability to a known date code and a trusted source is the main concern for a BOM line that still needs this exact order code.
50 ns trr — the switching-speed decision
At 50 ns trr, this diode recovers fast enough for continuous-conduction-mode (CCM) boost PFC at switching frequencies up to around 100 kHz without excessive reverse-recovery losses. The 2 V forward drop at 10 A is typical for a 600 V ultrafast — a trade-off: lower Vf would mean slower recovery, higher Vf would mean more conduction loss. For a 10 A average load per diode, the conduction loss runs about 20 W per die at full current, so the D2PAK's thermal pad and board copper are part of the thermal design, not an afterthought.
Common-cathode pair — topology fit
The 1 Pair Common Cathode configuration means the two anodes are separate and the cathodes are tied together internally. That matches center-tapped secondary rectifiers (cathode to the output, anodes to each winding end) and interleaved boost PFC where two inductors share a common output rail. It also saves board space versus two discrete SOD-123 or SMB devices — one D2PAK replaces two separate packages, which simplifies layout and reduces placement cost.