<PAGE>   1



                                                                      Exhibit 11

               Unitrode Corporation and Consolidated Subsidiaries
           Computation of Primary and Fully Diluted Earnings per Share
                      (in thousands except per share data)


<TABLE>
<CAPTION>

Three months ended                                    August 2, 1997    July 27, 1996
-------------------------------------------------------------------------------------

<S>                                                      <C>              <C>    
Net income                                               $ 8,118          $ 4,708
                                                         =======          =======

Primary Earnings Per Share:
---------------------------
Weighted average of common shares outstanding             11,763           11,510
Equivalent shares arising from the assumed
  exercise of stock options                                  693              328
                                                         -------          -------
Weighted average of common and common
  equivalent shares outstanding                           12,456           11,838
                                                         =======          =======

Net income                                               $   .65          $   .40
                                                         =======          =======

Fully diluted earnings per share:
---------------------------------
Weighted average of common and common
  equivalent shares outstanding
  (as determined for Primary earnings
  per share above)                                        12,456           11,838
Incremental shares to reflect full
  dilution                                                    96(1)            --(1)
                                                         -------          -------   
Weighted average of common and common
  equivalent shares outstanding, as
  adjusted                                                12,552           11,838
                                                         =======          =======

Net income                                               $   .65          $   .40
                                                         =======          =======
</TABLE>





(1)   This calculation is submitted in accordance with Regulation S-K item
      601(b)(11) although not required by footnote 2 to paragraph 14 of APB
      Opinion No. 15 because it results in dilution of less than 3%.


<PAGE>   2



                                                                      Exhibit 11

               Unitrode Corporation and Consolidated Subsidiaries
           Computation of Primary and Fully Diluted Earnings per Share
                      (in thousands except per share data)


<TABLE>
<CAPTION>

Six months ended                                      August 2, 1997    July 27, 1996
-------------------------------------------------------------------------------------

<S>                                                      <C>              <C>    
Net income                                               $14,704          $ 9,969
                                                         =======          =======

Primary earnings per share:
---------------------------
Weighted average of common shares outstanding             11,721           11,494
Equivalent shares arising from the assumed
  exercise of stock options                                  605              352
                                                         -------          -------
Weighted average of common and common
  equivalent shares outstanding                           12,326           11,846
                                                         =======          =======


Net income                                               $  1.19          $   .84
                                                         =======          =======

Fully diluted earnings per share:
---------------------------------
Weighted average of common and common
  equivalent shares outstanding
  (as determined for Primary earnings
  per share above)                                        12,326           11,846
Incremental shares to reflect full
  dilution                                                    87(1)            --(1)
                                                         -------          -------   
Weighted average of common and common
  equivalent shares outstanding, as
  adjusted                                                12,413           11,846
                                                         =======          =======

Net income                                               $  1.18          $   .84
                                                         =======          =======
</TABLE>


(1)   This calculation is submitted in accordance with Regulation S-K item
      601(b)(11) although not required by footnote 2 to paragraph 14 of APB
      Opinion No. 15 because it results in dilution of less than 3%.