Part identification help needed? Diode SO8 package with logo
I've done a bit of googling and have found that the logo is for Protek Devices.

And the datasheet can be found here: http://datasheet.octopart.com/ET721-LF-T7-Protek-datasheet-632479.pdf

The marking STA is shown on page 2. I would say that 0551 is a batch number. Sometimes surface mount component markings can be confusing as to which characters form the part number and which ones are either date codes or batch numbers.

FYI, the search term I used to find this was "diode array marking STA" it was the 8th result on the first page. But there were a few hits that would also get you the information you want.