<?xml version="1.0"?>

<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2003-07-17</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001096325</issuerCik>
        <issuerName>INTERSIL CORP/DE</issuerName>
        <issuerTradingSymbol>ISIL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000831001</rptOwnerCik>
            <rptOwnerName>CITIGROUP INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>399 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10043</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001105742</rptOwnerCik>
            <rptOwnerName>CITIGROUP HOLDINGS CO</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE RODNEY SQUARE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WILMINGTON</rptOwnerCity>
            <rptOwnerState>DE</rptOwnerState>
            <rptOwnerZipCode>19899</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000020405</rptOwnerCik>
            <rptOwnerName>CITICORP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>399 PARK AVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10043</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000036684</rptOwnerCik>
            <rptOwnerName>CITIBANK NA</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>399 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10043</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000356516</rptOwnerCik>
            <rptOwnerName>CITICORP VENTURE CAPITAL LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>399 PARK AVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10043</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>

        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2003-07-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1000000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2050118</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Subsidiary</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

    </nonDerivativeTable>

    <derivativeTable>

        <derivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F6"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2003-07-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1000000</value>
                    <footnoteId id="F4"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1000000</value>
                    <footnoteId id="F4"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Subsidiary</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>

    </derivativeTable>

    <footnotes>
        <footnote id="F1">The reported securities represent 1,050,118 shares of Class A Common Stock (&quot;Class A Common&quot;) held by an affiliate of Citicorp Venture Capital Ltd. (&quot;CVC&quot;) and 1,000,000 shares of Class A Common held by CVC.</footnote>
        <footnote id="F2">An employee of CVC serves on the Issuer's Board of Directors. CVC is a wholly owned subsidiary of Citibank, N.A. (&quot;Citibank&quot;), which is a wholly owned subsidiary of Citicorp, which is a wholly owned subsidiary of Citigroup Holdings Company (&quot;Citigroup Holdings&quot;), which is a wholly owned subsidiary of Citigroup Inc. (&quot;Citigroup&quot;). Each of Citigroup, Citigroup Holdings, Citicorp, and Citibank disclaims beneficial ownership of the shares reported herein except to the extent of their pecuniary interests therein.</footnote>
        <footnote id="F3">N/A</footnote>
        <footnote id="F4">Shares of Class B Common Stock (&quot;Class B Common&quot;) are convertible into shares of Class A Common on a 1:1 basis, provided that such conversion would be permitted only to the extent that the holder of shares to be converted would be permitted, under applicable law, to hold the total number of shares of Class A Common which would be held after giving effect to such conversion.</footnote>
        <footnote id="F5">Immediate</footnote>
        <footnote id="F6">1:1</footnote>
    </footnotes>


    <ownerSignature>
        <signatureName>Citigroup Inc., By: /s/ Serena D. Moe, Assistant Secretary</signatureName>
        <signatureDate>2003-07-17</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>Citigroup Holdings Company, By: /s/ Serena D. Moe, Assistant Secretary</signatureName>
        <signatureDate>2003-07-17</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>Citicorp, By: /s/ Serena D. Moe, Assistant Secretary</signatureName>
        <signatureDate>2003-07-17</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>Citibank, N.A., By: /s/ Serena D. Moe, Assistant Secretary</signatureName>
        <signatureDate>2003-07-17</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>Citicorp Venture Capital Ltd., By: /s/ Anthony Mirra, Vice President</signatureName>
        <signatureDate>2003-07-17</signatureDate>
    </ownerSignature>

</ownershipDocument>

