<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-03-21</periodOfReport>

    <issuer>
        <issuerCik>0000097476</issuerCik>
        <issuerName>TEXAS INSTRUMENTS INC</issuerName>
        <issuerTradingSymbol>TXN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001193456</rptOwnerCik>
            <rptOwnerName>ADAMS JAMES R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>12500 TI BOULEVARD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DALLAS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75243</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>315411</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1450</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Partnership</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>271550</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3031.87</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust--401(k)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>465.67</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust--PS</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1</value>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-03-21</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>235.71</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>28.28</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F6"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>235.71</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>24985.49</value>
                    <footnoteId id="F6"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F2">Shares held in trust for the benefit of family members of which reporting person is trustee.  Beneficial ownership by reporting person disclaimed.</footnote>
        <footnote id="F1">Shares held by family limited partnership of which the reporting person is a general partner.  Reporting person disclaims beneficial ownership except to the extent of his pecuniary interest in the partnership.</footnote>
        <footnote id="F3">Estimated shares attributable to TI 401(k) Account as of 1-31-08.   (Interests in this account are denominated in units.  Consequently, share amount shown is an estimate.)  This statement does not include changes in beneficial ownership of shares held in this account occurring after 1-31-08 that are eligible for deferred reporting on Form 5.</footnote>
        <footnote id="F6">Stock units credited under the Texas Instruments 2003 Director Compensation Plan, to be settled in common stock of the Issuer following the reporting person's termination of service as a director of the Issuer.</footnote>
        <footnote id="F4">Estimated shares attributable to TI Universal Profit Sharing Account as of 1-31-08.  (Interests in this account are denominated in units.  Consequently, share amount shown is an estimate.)  This statement does not include changes in beneficial ownership of shares held in such account occurring after 1-31-08 that are eligible for deferred reporting on Form 5.</footnote>
        <footnote id="F5">Security converts to common stock on a one-for-one basis.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>DANIEL M. DRORY, ATTORNEY IN FACT</signatureName>
        <signatureDate>2008-03-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2008-03-21
0000097476
TEXAS INSTRUMENTS INC
TXN
0001193456
ADAMS JAMES R
12500 TI BOULEVARD
DALLAS
TX
75243
1
0
0
0
Common Stock
315411
D
Common Stock
1450
I
By Partnership
Common Stock
271550
I
By Trust
Common Stock
3031.87
I
By Trust--401(k)
Common Stock
465.67
I
By Trust--PS
Stock Units
1
2008-03-21
4
A
0
235.71
28.28
A
Common Stock
235.71
24985.49
D
Shares held in trust for the benefit of family members of which reporting person is trustee.  Beneficial ownership by reporting person disclaimed.
Shares held by family limited partnership of which the reporting person is a general partner.  Reporting person disclaims beneficial ownership except to the extent of his pecuniary interest in the partnership.
Estimated shares attributable to TI 401(k) Account as of 1-31-08.   (Interests in this account are denominated in units.  Consequently, share amount shown is an estimate.)  This statement does not include changes in beneficial ownership of shares held in this account occurring after 1-31-08 that are eligible for deferred reporting on Form 5.
Stock units credited under the Texas Instruments 2003 Director Compensation Plan, to be settled in common stock of the Issuer following the reporting person's termination of service as a director of the Issuer.
Estimated shares attributable to TI Universal Profit Sharing Account as of 1-31-08.  (Interests in this account are denominated in units.  Consequently, share amount shown is an estimate.)  This statement does not include changes in beneficial ownership of shares held in such account occurring after 1-31-08 that are eligible for deferred reporting on Form 5.
Security converts to common stock on a one-for-one basis.
DANIEL M. DRORY, ATTORNEY IN FACT
2008-03-24