UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                                (Amendment No.3)*



                         Monolithic Power Systems, Inc.
--------------------------------------------------------------------------------
                                (Name of Issuer)


                         Common Stock, $0.001 Par Value
--------------------------------------------------------------------------------
                         (Title of Class of Securities)


                                    609839105

--------------------------------------------------------------------------------
                                 (CUSIP Number)


                                December 31, 2007
--------------------------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)


     Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:

          [_] Rule 13d-1(b)

          [x] Rule 13d-1(c)

          [_] Rule 13d-1(d)


----------
*    The remainder of this cover page shall be filled out for a reporting
     person's initial filing on this form with respect to the subject class of
     securities, and for any subsequent amendment containing information which
     would alter the disclosures provided in a prior cover page.


     The information required in the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("Act") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other provisions of the Act (however, see
the Notes).



CUSIP No. 609839105
-------------------


1.   NAME OF REPORTING PERSONS
     I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

          Philippe Laffont

2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
     (SEE INSTRUCTIONS)                                                 (a) [_]
                                                                        (b) [X]

3.   SEC USE ONLY



4.   CITIZENSHIP OR PLACE OF ORGANIZATION

          France

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.   SOLE VOTING POWER

          921,116

6.   SHARED VOTING POWER

          0

7.   SOLE DISPOSITIVE POWER

          921,116

8.   SHARED DISPOSITIVE POWER

          0

9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

          921,116

10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
     CERTAIN SHARES (SEE INSTRUCTIONS)                                      [_]

11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

          2.8%

12.  TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

          IN

--------------------------------------------------------------------------------



CUSIP No. 609839105
-------------------


Item 1(a).  Name of Issuer:

                 Monolithic Power Systems, Inc.
            --------------------------------------------------------------------

      (b).  Address of Issuer's Principal Executive Offices:

                  983 University Avenue
                  Building A
                  Los Gatos, California 95032
            --------------------------------------------------------------------


Item 2(a).  Name, Principal Business Address, and Citizenship of Persons Filing:

                 Philippe Laffont - France
                 126 East 56th Street
                 New York, New York 10022
            --------------------------------------------------------------------


      (d).  Title of Class of Securities:

                 Common Stock, $0.001 Par Value
            --------------------------------------------------------------------

      (e).  CUSIP Number:

                 609839105
            --------------------------------------------------------------------


Item 3.     If This Statement is filed pursuant to ss.240.13d-1(b) or
            240.13d-2(b), or (c), check whether the person filing is a:

      (a) [_]    Broker or dealer registered under Section 15 of the Exchange
                 Act (15 U.S.C. 78c).

      (b) [_]    Bank as defined in Section 3(a)(6) of the Exchange Act (15
                 U.S.C. 78c).

      (c) [_]    Insurance company as defined in Section 3(a)(19) of the
                 Exchange Act (15 U.S.C. 78c).

      (d) [_]    Investment company registered under Section 8 of the
                 Investment Company Act of 1940 (15 U.S.C. 80a-8).

      (e) [_]    An investment adviser in accordance with
                 s.240.13d-1(b)(1)(ii)(E);

      (f) [_]    An employee benefit plan or endowment fund in accordance with
                 s.240.13d-1(b)(1)(ii)(F);

      (g) [_]    A parent holding company or control person in accordance with
                 Rule 13d-1(b)(1)(ii)(G);

      (h) [_]    A savings association as defined in Section 3(b) of the
                 Federal Deposit Insurance Act (12 U.S.C.1813);

      (i) [_]    A church plan that is excluded from the definition of an
                 investment company under Section 3(c)(14) of the Investment
                 Company Act of 1940 (15 U.S.C. 80a-3);

      (j) [_]    Group, in accordance with s.240.13d-1(b)(1)(ii)(J).


Item 4.     Ownership.

                 Provide the following information regarding the aggregate
            number and percentage of the class of securities of the issuer
            identified in Item 1.

      (a)   Amount beneficially owned:

                 Philippe Laffont - 921,116
            --------------------------------------------------------------------

      (b)   Percent of class:

                 Philippe Laffont - 2.8%
            --------------------------------------------------------------------

      (c)   Number of shares as to which the person has:

         (i)     Sole power to vote or to direct the vote:

                      Philippe Laffont - 921,116

         (ii)    Shared power to vote or to direct the vote:

                      Philippe Laffont - 0

         (iii)   Sole power to dispose or to direct the disposition of:

                      Philippe Laffont - 921,116

         (iv)    Shared power to dispose or to direct the disposition of:

                      Philippe Laffont - 0


Item 5.     Ownership of Five Percent or Less of a Class.

                 If this statement is being filed to report the fact that as of
            the date hereof the reporting person has ceased to be the beneficial
            owner of more than five percent of the class of securities, check
            the following [x].

            --------------------------------------------------------------------


Item 6.     Ownership of More Than Five Percent on Behalf of Another Person.

                 If any other person is known to have the right to receive or
            the power to direct the receipt of dividends from, or the proceeds
            from the sale of, such securities, a statement to that effect should
            be included in response to this item and, if such interest relates
            to more than five percent of the class, such person should be
            identified. A listing of the shareholders of an investment company
            registered under the Investment Company Act of 1940 or the
            beneficiaries of employee benefit plan, pension fund or endowment
            fund is not required.

                 The securities are held in the name of two private investment
            funds. Philippe Laffont is reporting beneficial ownership under Item
            4 as the managing member of the investment manager and general
            partner of these funds.

                 Mr. Laffont disclaims beneficial ownership in the shares
            reported herein except to the extent of his pecuniary interest
            therein.
            --------------------------------------------------------------------


Item 7.     Identification and Classification of the Subsidiary Which Acquired
            the Security Being Reported on by the Parent Holding Company or
            Control Person.

                 If a parent holding company or Control person has filed this
            schedule, pursuant to Rule 13d-1(b)(1)(ii)(G), so indicate under
            Item 3(g) and attach an exhibit stating the identity and the Item 3
            classification of the relevant subsidiary. If a parent holding
            company or control person has filed this schedule pursuant to Rule
            13d-1(c) or Rule 13d-1(d), attach an exhibit stating the
            identification of the relevant subsidiary.

                 N/A
            --------------------------------------------------------------------


Item 8.     Identification  and  Classification  of Members of the Group.

                 If a group has filed this schedule pursuant to
            ss.240.13d-1(b)(1)(ii)(J), so indicate under Item 3(j) and attach an
            exhibit stating the identity and Item 3 classification of each
            member of the group. If a group has filed this schedule pursuant to
            ss.240.13d-1(c) or ss.240.13d-1(d), attach an exhibit stating the
            identity of each member of the group.

                 N/A
            --------------------------------------------------------------------


Item 9.     Notice of Dissolution of Group.

                 Notice of dissolution of a group may be furnished as an
            exhibit stating the date of the dissolution and that all further
            filings with respect to transactions in the security reported on
            will be filed, if required, by members of the group, in their
            individual capacity. See Item 5.

                 N/A
            --------------------------------------------------------------------


Item 10.    Certification.

      (b)   The following certification shall be included if the statement is
            filed pursuant to Rule 13d-1(c):

            By signing below I certify that, to the best of my knowledge and
            belief, the securities referred to above were not acquired and are
            not held for the purpose of or with the effect of changing or
            influencing the control of the issuer of the securities and were not
            acquired and are not held in connection with or as a participant in
            any transaction having such purpose or effect.

     After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.


Philippe Laffont*


/s/ Philippe Laffont
------------------------


February 14, 2008


*    The Reporting Person disclaims beneficial ownership in the shares reported
     herein except to the extent of his pecuniary interest therein.





SK 02984 0001 852345