SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   FORM 8-A/A

                FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                     PURSUANT TO SECTION 12(b) OR (g) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


                        MICROCHIP TECHNOLOGY INCORPORATED
             ------------------------------------------------------
             (Exact name of Registrant as specified in its charter)


                DELAWARE                                 86-0629024
- ----------------------------------------       ---------------------------------
(State of incorporation or organization)       (IRS Employer Identification No.)


                          2355 WEST CHANDLER BOULEVARD
                             CHANDLER, AZ 85224-6199
               ---------------------------------------------------
               (Address of principal executive offices) (Zip Code)


Securities to be registered pursuant to Section 12(b) of the Act:

Title of each class                               Name of each exchange on which
to be so registered                               each class is to be registered
- -------------------                               ------------------------------
       None                                              Not applicable


     If this form relates to the registration of a class of securities  pursuant
to  Section  12(b) of the  Exchange  Act and is  effective  pursuant  to General
Instruction A.(c), check the following box. [ ]

     If this form relates to the registration of a class of securities  pursuant
to  Section  12(g) of the  Exchange  Act and is  effective  pursuant  to General
Instruction A.(d), check the following box. [X]

     Securities  Act  registration  statement  file  number  to which  this form
relates: N/A

Securities to be registered pursuant to Section 12(g) of the Act:

                         Preferred Share Purchase Rights
                         -------------------------------
                                (Title of Class)

ITEM 1. DESCRIPTION OF SECURITIES TO BE REGISTERED.

     On February 13, 1995,  Microchip  Technology  Incorporated  (the "COMPANY")
filed a  Registration  Statement  on  Form  8-A  with  the  Securities  Exchange
Commission  (the  "COMMISSION")  in order to register  preferred  share purchase
rights  issuable in  accordance  with the terms of the  Preferred  Shares Rights
Agreement  (the  "PRIOR  RIGHTS  AGREEMENT")  between  the Company and Bank One,
Arizona, N.A., as rights agent.

     On October 11,  1999,  the Company and Norwest  Bank  Minnesota,  N.A.,  as
successor rights agent,  entered into the Amended and Restated  Preferred Shares
Rights  Agreement (the "AMENDED RIGHTS  AGREEMENT"),  which supersedes the Prior
Rights Agreement as originally executed.  The following summarizes the principal
terms of the Amended  Rights  Agreement.  This summary is a general  description
only and is  qualified  in its  entirety  by  reference  to the  Amended  Rights
Agreement.

RIGHTS EVIDENCED BY COMMON SHARE CERTIFICATES

     The Rights will not be  exercisable  until the  Distribution  Date (defined
below).  Certificates for the Rights ("RIGHTS CERTIFICATES") will not be sent to
stockholders  and the Rights  will  attach to and trade only  together  with the
Common Shares. Accordingly,  Common Share certificates outstanding on the Record
Date will evidence the Rights  related  thereto,  and Common Share  certificates
issued  after the Record Date will contain a notation  incorporating  the Rights
Agreement by reference.  Until the Distribution  Date (or earlier  redemption or
expiration  of the Rights),  the surrender or transfer of any  certificates  for
Common  Shares,  outstanding as of the Record Date,  even without  notation or a
copy of the Summary of Rights being attached  thereto,  will also constitute the
transfer of the Rights  associated  with the Common Shares  represented  by such
certificate.

DISTRIBUTION DATE

     The Rights will separate from the Common Shares,  Rights  Certificates will
be issued and the Rights  will  become  exercisable  upon the earlier of: (i) 10
days  following a public  announcement  that a person or group of  affiliated or
associated persons (an "ACQUIRING  PERSON") has acquired,  or obtained the right
to  acquire,  beneficial  ownership  of 15% or  more of the  outstanding  Common
Shares,  or (ii) 10 days (or such later date as may be  determined  by action of
the Company's Board of Directors) following the commencement of, or announcement
of an intention to make, a tender offer or exchange  offer the  consummation  of
which would  result in the  beneficial  ownership by a person or group of 15% or
more of the outstanding  Common Shares. The earlier of such dates is referred to
as the "DISTRIBUTION DATE."

ISSUANCE OF RIGHTS CERTIFICATES; EXPIRATION OF RIGHTS

     As soon as practicable  following the  Distribution  Date,  separate Rights
Certificates  will be mailed to holders of record of the Common Shares as of the
close of business on the Distribution Date and such separate Rights Certificates
alone will evidence the Rights from and after the Distribution  Date. All Common
Shares issued prior to the Distribution Date will be issued with Rights.  Common
Shares  issued  after the  Distribution  Date may be issued  with Rights if such
shares

are issued (i) upon the conversion of outstanding  convertible debentures or any
other  convertible  securities  issued after adoption of the Rights Agreement or
(ii) pursuant to the exercise of stock options or under  employee  benefit plans
or  arrangements  unless such  issuance  would result in (or create a risk that)
such options,  plans or arrangements  would not qualify for otherwise  available
special tax treatment. Except as otherwise determined by the Board of Directors,
no other Common  Shares issued after the  Distribution  Date will be issued with
Rights.  The Rights  will  expire on the  earliest  of (i) October 11, 2009 (THE
"FINAL EXPIRATION DATE"), (ii) redemption or exchange of the Rights as described
below, or (iii) consummation of an acquisition of the Company satisfying certain
conditions  by a person who  acquired  shares  pursuant to a Permitted  Offer as
described below.

INITIAL EXERCISE OF THE RIGHTS

     Following  the  Distribution  Date,  and until the Close of Business on the
Expiration  Date or one of the further events  described  below,  holders of the
Rights will be entitled to receive, upon exercise and the payment of $250.00 per
Right, one one-hundredth of a share of the Series A Preferred. In the event that
the Company does not have sufficient Series A Preferred available for all Rights
to be  exercised,  or the Board  decides that such action is  necessary  and not
contrary to the interests of Rights holders,  the Company may instead substitute
cash, assets or other securities for the Series A Preferred for which the Rights
would have been exercisable under this provision or as described below.

RIGHT TO BUY COMPANY COMMON SHARES

     Unless the  Rights are  earlier  redeemed,  in the event that an  Acquiring
Person  becomes  the  beneficial  owner of 15% or more of the  Company's  Common
Shares then  outstanding,  then each holder of a Right which has not theretofore
been exercised (other than Rights  beneficially  owned by the Acquiring  Person,
which will thereafter be void) will  thereafter have the right to receive,  upon
exercise,  Common Shares  having a value equal to two times the Purchase  Price.
Rights are not  exercisable  following  the  occurrence of an event as described
above until such time as the Rights are no longer  redeemable  by the Company as
set forth below.

RIGHT TO BUY ACQUIRING COMPANY STOCK

     Similarly, unless the Rights are earlier redeemed, in the event that, after
an Acquiring Person becomes the beneficial owner of 15% of more of the Company's
Common Shares then outstanding, (i) the Company is acquired in a merger or other
business  combination  transaction,  or  (ii)  50%  or  more  of  the  Company's
consolidated assets or earning power are sold (other than in transactions in the
ordinary course of business),  proper provision must be made so that each holder
of a  Right  which  has  not  theretofore  been  exercised  (other  than  Rights
beneficially owned by the Acquiring Person,  which will thereafter be void) will
thereafter have the right to receive,  upon exercise,  shares of common stock of
the acquiring company having a value equal to two times the Purchase Price.

EXCHANGE PROVISION

     At any time after the acquisition by an Acquiring  Person of 15% or more of
the Company's  outstanding  Common Shares and prior to the  acquisition  by such
Acquiring Person of 50% or more

                                       -2-

of the  Company's  outstanding  Common  Shares,  the Board of  Directors  of the
Company  may  exchange  the Rights  (other than  Rights  owned by the  Acquiring
Person),  in whole or in part,  at an  exchange  ratio of one  Common  Share per
Right.

REDEMPTION

     At any time on or prior to the close of  business on the earlier of (i) the
Distribution  Date, or (ii) the Close of Business on the Final  Expiration Date,
the  Company  may  redeem the  Rights in whole,  but not in part,  at a price of
$0.001 per Right.

ADJUSTMENTS TO PREVENT DILUTION

     The Exercise Price payable,  the number of Rights, and the number of Series
A Preferred  or Common  Shares or other  securities  or property  issuable  upon
exercise of the Rights are subject to adjustment from time to time in connection
with the dilutive issuances by the Company as set forth in the Rights Agreement.
With certain  exceptions,  no adjustment in the Purchase  Price will be required
until  cumulative  adjustments  require  an  adjustment  of at  least 1% in such
Purchase Price.

CASH PAID INSTEAD OF ISSUING FRACTIONAL SHARES

     No fractional portion less than integral multiples of one Common Share will
be issued upon  exercise of a Right and in lieu  thereof,  an adjustment in cash
will be made based on the market price of the Common  Shares on the last trading
date prior to the date of exercise.

NO STOCKHOLDERS' RIGHTS PRIOR TO EXERCISE

     Until a Right is  exercised,  the  holder  thereof,  as such,  will have no
rights as a stockholder  of the Company  (other than any rights  resulting  from
such holder's ownership of Common Shares),  including,  without limitation,  the
right to vote or to receive dividends.

AMENDMENT OF RIGHTS AGREEMENT

     The terms of the  Rights  and the  Rights  Agreement  may be amended in any
respect  without  the  consent  of  the  Rights  holders  on  or  prior  to  the
Distribution Date; thereafter,  the terms of the Rights and the Rights Agreement
may be amended  without the  consent of the Rights  holders in order to cure any
ambiguities  or to make changes which do not  adversely  affect the interests of
Rights holders (other than the Acquiring Person).

RIGHTS AND PREFERENCES OF THE SERIES A PREFERRED

     Each one  one-hundredth  of a share of Series A  Preferred  has  rights and
preferences substantially equivalent to those of one Common Share.

CERTAIN ANTI-TAKEOVER EFFECTS

     The Rights  approved by the Board are  designed to protect and maximize the
value of the  outstanding  equity  interests  in the  Company in the event of an
unsolicited attempt by an acquiror to

                                       -3-

take over the  Company,  in a manner or on terms  not  approved  by the Board of
Directors.  Takeover attempts frequently include coercive tactics to deprive the
Company's  Board of Directors and its  stockholders  of any real  opportunity to
determine the destiny of the Company. The Rights have been declared by the Board
in order to deter such tactics,  including a gradual  accumulation  of shares in
the open  market of a 15% or greater  position  to be  followed by a merger or a
partial or two-tier tender offer that does not treat all  stockholders  equally.
These  tactics  unfairly  pressure  stockholders,  squeeze  them  out  of  their
investment  without  giving them any real  choice and  deprive  them of the full
value of their shares.

     The Rights are not  intended  to prevent a takeover of the Company and will
not do so.  Subject  to the  restrictions  described  above,  the  Rights may be
redeemed  by  the  Company  at  $0.001  per  Right  at  any  time  prior  to the
Distribution Date. Accordingly,  the Rights should not interfere with any merger
or business combination approved by the Board of Directors.

     Issuance of the Rights does not in any way weaken the financial strength of
the Company or  interfere  with its business  plans.  The issuance of the Rights
themselves has no dilutive effect,  will not affect reported earnings per share,
should not be taxable to the Company or to its stockholders, and will not change
the way in which the Company's shares are presently traded.  The Company's Board
of Directors  believes that the Rights represent a sound and reasonable means of
addressing  the  complex  issues  of  corporate   policy  created  by  corporate
takeovers.

     However,  the Rights may have the effect of  rendering  more  difficult  or
discouraging  an acquisition  of the Company deemed  undesirable by the Board of
Directors.  The Rights may cause substantial  dilution to a person or group that
attempts  to acquire  the  Company on terms or in a manner not  approved  by the
Company's Board of Directors,  except pursuant to an offer  conditioned upon the
negation, purchase or redemption of the Rights.

ITEM 2. EXHIBITS.

     1.*  Amended and Restated  Preferred Shares Rights  Agreement,  dated as of
          October 11, 1999 between Microchip Technology Incorporated and Norwest
          Bank   Minnesota,   N.A.,   including  the  Amended   Certificate   of
          Designations,  the  form of  Rights  Certificate  and the  Stockholder
          Rights Plan attached thereto as Exhibits A, B and C, respectively.

*  Incorporated  by  reference  to the  Current  Report on Form 8-K filed by the
   Company on or about October 11, 1999

                                       -4-

                                    SIGNATURE

     Pursuant to the  requirements of Section 12 of the Securities  Exchange Act
of 1934, the Registrant has duly caused this Registration Statement to be signed
on its behalf by the undersigned, thereto duly authorized.


                                        MICROCHIP TECHNOLOGY INCORPORATED

Date: October 11, 1999

                                        By: /s/ C. Philip Chapman
                                            ------------------------------------
                                            C. Philip Chapman
                                            Vice President, Chief Financial
                                            Officer and Secretary