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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 xOlhv+OjTrqlBuUIBkkhqg==

<SEC-DOCUMENT>0001413753-08-000094.txt : 20081216
<SEC-HEADER>0001413753-08-000094.hdr.sgml : 20081216
<ACCEPTANCE-DATETIME>20081216184352
ACCESSION NUMBER:		0001413753-08-000094
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20081215
FILED AS OF DATE:		20081216
DATE AS OF CHANGE:		20081216

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SEMTECH CORP
		CENTRAL INDEX KEY:			0000088941
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		IRS NUMBER:				952119684
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0127

	BUSINESS ADDRESS:	
		STREET 1:		200 FLYNN ROAD
		CITY:			CAMARILLO
		STATE:			CA
		ZIP:			93012-8790
		BUSINESS PHONE:		8054982111

	MAIL ADDRESS:	
		STREET 1:		200 FLYNN ROAD
		CITY:			CAMARILLO
		STATE:			CA
		ZIP:			93012-8790

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MAHESWARAN MOHAN
		CENTRAL INDEX KEY:			0001224946

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-06395
		FILM NUMBER:		081253389

	BUSINESS ADDRESS:	
		STREET 1:		C/O INTERSIL CORP
		STREET 2:		675 TRADE ZONE BLVD
		CITY:			MILPITAS
		STATE:			CA
		ZIP:			95035
		BUSINESS PHONE:		805-498-2111

	MAIL ADDRESS:	
		STREET 1:		200 FLYNN ROAD
		CITY:			CAMARILLO
		STATE:			CA
		ZIP:			93012
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-12-15</periodOfReport>

    <issuer>
        <issuerCik>0000088941</issuerCik>
        <issuerName>SEMTECH CORP</issuerName>
        <issuerTradingSymbol>SMTC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001224946</rptOwnerCik>
            <rptOwnerName>MAHESWARAN MOHAN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 FLYNN ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CAMARILLO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93012</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-12-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2817</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.63</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>90206</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks>A portion of a previously reported stock award vested on December 15, 2008.  This Form 4 reports the withholding of some of the vested shares to pay the tax liability arising upon vesting.</remarks>

    <ownerSignature>
        <signatureName>Mohan Maheswaran by Randall H. Holliday under Power of Attorney dated November 4, 2008 (copy on file)</signatureName>
        <signatureDate>2008-12-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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