<SEC-DOCUMENT>0001567619-19-006574.txt : 20190311
<SEC-HEADER>0001567619-19-006574.hdr.sgml : 20190311
<ACCEPTANCE-DATETIME>20190311170950
ACCESSION NUMBER:		0001567619-19-006574
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190311
FILED AS OF DATE:		20190311
DATE AS OF CHANGE:		20190311

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			GRILLO ANTHONY
		CENTRAL INDEX KEY:			0001070847

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-20388
		FILM NUMBER:		19673052

	MAIL ADDRESS:	
		STREET 1:		PLEASANTVILLE RD
		CITY:			NEW VERNON
		STATE:			NJ
		ZIP:			07976

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			LITTELFUSE INC /DE
		CENTRAL INDEX KEY:			0000889331
		STANDARD INDUSTRIAL CLASSIFICATION:	SWITCHGEAR & SWITCHBOARD APPARATUS [3613]
		IRS NUMBER:				363795742
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1229

	BUSINESS ADDRESS:	
		STREET 1:		8755 WEST HIGGINS ROAD
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60631
		BUSINESS PHONE:		773-628-1000

	MAIL ADDRESS:	
		STREET 1:		8755 WEST HIGGINS ROAD
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60631
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-03-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000889331</issuerCik>
        <issuerName>LITTELFUSE INC /DE</issuerName>
        <issuerTradingSymbol>LFUS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001070847</rptOwnerCik>
            <rptOwnerName>GRILLO ANTHONY</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>8755 W. HIGGINS ROAD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 500</rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60631</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-03-11</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>L</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>43</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>190.73</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>47219</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares acquired pursuant to reinvestment of dividends on shares held pursuant to a deferred compensation plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Hans Weinburger, by power of attorney</signatureName>
        <signatureDate>2019-03-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
