As of 2025, Sanyo (now ON Semiconductor) has discontinued these hybrids for nearly two decades. The datasheet is easy to find (search for the PDF), but the chip is not. Most "STK412-530" units sold online are counterfeit Chinese clones. A genuine datasheet describes a chip with a specific beige ceramic substrate; counterfeits are often black epoxy with lower current handling.
Counterfeit STK ICs are rampant. Use these tips from datasheet comparisons: stk412530 datasheet