<SEC-DOCUMENT>0001567619-20-018678.txt : 20201104
<SEC-HEADER>0001567619-20-018678.hdr.sgml : 20201104
<ACCEPTANCE-DATETIME>20201104142442
ACCESSION NUMBER:		0001567619-20-018678
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20201104
FILED AS OF DATE:		20201104
DATE AS OF CHANGE:		20201104

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Sethna Meenal
		CENTRAL INDEX KEY:			0001643464

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-20388
		FILM NUMBER:		201286168

	MAIL ADDRESS:	
		STREET 1:		8755 WEST HIGGINS ROAD
		STREET 2:		SUITE 500
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60631

	FORMER NAME:	
		FORMER CONFORMED NAME:	Seetha Meenal
		DATE OF NAME CHANGE:	20150527

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:			1226

	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>2020-11-04</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001643464</rptOwnerCik>
            <rptOwnerName>Sethna Meenal</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>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive VP, CFO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-11-04</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2440</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>206.05</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13305</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares were sold in multiple transactions at prices ranging from $206.00 to $206.58, inclusive. This amount represents the weighted average sale price of such transactions. The reporting person undertakes to provide full information regarding the number of shares sold at each separate price upon request of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Hans Weinburger, by power of attorney</signatureName>
        <signatureDate>2020-11-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
