<SEC-DOCUMENT>0001312593-24-000008.txt : 20241108
<SEC-HEADER>0001312593-24-000008.hdr.sgml : 20241108
<ACCEPTANCE-DATETIME>20241108124738
ACCESSION NUMBER:		0001312593-24-000008
CONFORMED SUBMISSION TYPE:	144
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20241108
DATE AS OF CHANGE:		20241108

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MONOLITHIC POWER SYSTEMS INC
		CENTRAL INDEX KEY:			0001280452
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		ORGANIZATION NAME:           	04 Manufacturing
		IRS NUMBER:				770466789
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		144
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	000-51026
		FILM NUMBER:		241439102

	BUSINESS ADDRESS:	
		STREET 1:		5808 LAKE WASHINGTON BLVD. NE
		CITY:			KIRKLAND
		STATE:			WA
		ZIP:			98033
		BUSINESS PHONE:		425-296-9956

	MAIL ADDRESS:	
		STREET 1:		5808 LAKE WASHINGTON BLVD. NE
		CITY:			KIRKLAND
		STATE:			WA
		ZIP:			98033

REPORTING-OWNER:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Tseng Saria
		CENTRAL INDEX KEY:			0001312593
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		144

	MAIL ADDRESS:	
		STREET 1:		79 GREAT OAKS BLVD
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95119
</SEC-HEADER>
<DOCUMENT>
<TYPE>144
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
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  <headerData>
    <submissionType>144</submissionType>
    <filerInfo>
      <filer>
        <filerCredentials>
          <cik>0001312593</cik>
          <ccc>XXXXXXXX</ccc>
        </filerCredentials>
      </filer>
      <liveTestFlag>LIVE</liveTestFlag>


    </filerInfo>
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  <formData>
    <issuerInfo>
      <issuerCik>0001280452</issuerCik>
      <issuerName>MONOLITHIC POWER SYSTEMS INC</issuerName>
      <secFileNumber>000-51026</secFileNumber>
      <issuerAddress>
        <com:street1>5808 LAKE WASHINGTON BLVD. NE</com:street1>
        <com:city>KIRKLAND</com:city>
        <com:stateOrCountry>WA</com:stateOrCountry>
        <com:zipCode>98033</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>425-296-9956</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Tseng Saria</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Officer</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Morgan Stanley Smith Barney LLC Executive Financial Services</name>
        <address>
          <com:street1>1 New York Plaza, 8th Floor</com:street1>
          <com:city>New York</com:city>
          <com:stateOrCountry>NY</com:stateOrCountry>
          <com:zipCode>10004</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>2172</noOfUnitsSold>
      <aggregateMarketValue>1683756.12</aggregateMarketValue>
      <noOfUnitsOutstanding>48780468</noOfUnitsOutstanding>
      <approxSaleDate>11/08/2024</approxSaleDate>
      <securitiesExchangeName>NASDAQ</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common Stock</securitiesClassTitle>
      <acquiredDate>11/08/2024</acquiredDate>
      <natureOfAcquisitionTransaction>Performance Shares</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>2172</amountOfSecuritiesAcquired>
      <paymentDate>11/08/2024</paymentDate>
      <natureOfPayment>Cash</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <noticeSignature>
      <noticeDate>11/08/2024</noticeDate>
      <signature>Saria Tseng</signature>
    </noticeSignature>
  </formData>
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</SEC-DOCUMENT>