The 2153 has Thailand in a dimple on the rear of the package and an empty
dimple on the diagonal, this structure the same as the ground off one, minus
the R 3 .
I wonder how many IR 8pin , that pinning packages , were available in 2008
and a year or two before. Unfortunately I don't like using isolation
transformers and scopes on SMPS to narrow down a bit more, if I regularly
dealt with SMPS failures then perhaps it would be different. If this one
wasn't a lot of difficult to probe SM around the DIP8 SMPS driiver ,hemmed
in by heatsinks and large caps then may have been different