I was looking through a datasheet, when I noticed this sentence:

TSOP package is suitable for cards, and reverse type TSOP is also provided.

What is a "reverse type" TSOP? I am familiar with TSOP packages.


1 Answer 1


The difference is shown on page 3 of the datasheet you linked to. It is not a difference in package, but a difference in pin arrangement. Compare the pins between the HM628128ALT and the HM628128ALR -- the pin functions are reflected. Page 2 indicates that the ...ALT version is "normal type" and the ...ALR version is "reverse type".

  • 6
    \$\begingroup\$ This allows chips to be mounted on both sides of the PCB with a minimum of wiring congestion. \$\endgroup\$
    – Dave Tweed
    Nov 19, 2018 at 19:58

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