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SM72485 / LM5009A Datasheet error

Rob Cameron
Prodigy 10 points
Other Parts Discussed in Thread: LM5009A, SM72485, LM5009

This is a heads up for TI to issue an errata and to help any designers presently using these parts.

In both the SM72485 and LM5009A, there is an error in the given formula to calculate Toff. The original LM5009 part has the correct formula in its datasheet and so apparently it is a copy error. 

In the SM72485 and LM5009A datasheets, equation 5 Toff is given by

TOFF = 10-5 / (0.285 + (VFB / 6.35 x 10-6 x RCL))

However, the correct formula as given in the LM5009 datasheet is actually

TOFF = 10-5 / (0.285 + VFB / ( 6.35 x 10-6 x RCL))

(notice the different position on the second parentheses).

BTW, someone asked what was the difference between the SM72485 and LM5009A parts- this is so far unanswered in the forum. I can't find any difference, aside from supply pricing and availability. I presume it is a marketing effort to "TI-ize" the National part naming after the acquisition. 

Cheers!