<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>119 - Disclosure - Credit Facility</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode /><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>P01_01_2013To06_30_2013</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0000944739</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2013-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-06-30T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS /><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol /><Labels><Label Key="CalendarSupplement" Id="0" Label="6 Months Ended" /><Label Key="Calendar" Id="1" Label="Jun. 30, 2013" /></Labels></Column></Columns><Rows><Row FlagID="0"><Id>1</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>1</Level><ElementName>us-gaap_DebtDisclosureAbstract</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Debt Disclosure [Abstract]</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>us-gaap_DebtDisclosureTextBlock</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>verboseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="P01_01_2013To06_30_2013" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>              &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif "&gt;  &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &lt;strong&gt;Note 13.&amp;#160;&amp;#160;&amp;#160;&amp;#160;Credit  Facility&lt;/strong&gt;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &lt;strong&gt;&amp;#160;&lt;/strong&gt;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; TEXT-INDENT: 45.35pt; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  On &lt;font style=" FONT-SIZE: 10pt"&gt;April 4, 2011&lt;/font&gt;, the Company  entered into an Amended and Restated Business Financing Agreement  (&lt;font style="BACKGROUND-COLOR: transparent"&gt;as amended from time  to time,&lt;/font&gt; the &amp;#8220;Financing Agreement&amp;#8221;) with Bridge  Bank N.A. (&amp;#8220;Bridge Bank&amp;#8221;) which amended and restated  its existing credit facility. During the first quarter of 2013, the  Company was not in compliance with a financial covenant of the  Financing Agreement. On April 10, 2013, the Company entered into  &lt;font style="BACKGROUND-COLOR: transparent"&gt;a Business Financing  Modification Agreement&lt;/font&gt; with Bridge Bank pursuant to which  Bridge Bank agreed to waive such noncompliance, make certain other  modifications and extend the maturity &lt;font style="BACKGROUND-COLOR: transparent"&gt;of the Financing Agreement&lt;/font&gt;  to July 3, 2013. The Company was in compliance with this financial  covenant as of June 30, 2013.&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; TEXT-INDENT: 45.35pt; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; TEXT-INDENT: 45.35pt; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  On July 3, 2013, the Company entered into a second Business  Financing Modification Agreement (the &amp;#8220;Second Modification  Agreement&amp;#8221;) with Bridge Bank, amending the terms of the  Financing Agreement. Pursuant to the terms of the Financing  Agreement, as amended, the maturity date of the Financing Agreement  was extended until July 3, 2014. The Financing Agreement as amended  contains customary representations, warranties, and affirmative and  negative covenants for facilities of its type, including the  payment of certain fees, restrictions on dispositions of the  Company&amp;#8217;s assets, changes in business, and incurrence of  certain indebtedness and encumbrances. The Financing Agreement, as  amended, by the Modification Agreement also contains customary  events of default, including payment defaults and breaches of  representations and warranties and covenants. If an event of  default occurs and is continuing, Bridge Bank has customary rights  and remedies under the Financing Agreement, as amended, including  the right to declare all outstanding indebtedness under the  facility immediately due and payable and ceasing to advance money  or extend credit.&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; TEXT-INDENT: 45.35pt; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &amp;#160;&lt;/div&gt;    &lt;div style="clear:both; FONT-FAMILY:Times New Roman;FONT-SIZE: 10pt;TEXT-ALIGN: justify; TEXT-INDENT: 45.35pt; MARGIN: 0pt 0px; FONT: 10pt Times New Roman, Times, Serif"&gt;  &lt;font style="BACKGROUND-COLOR: transparent"&gt;The Financing  Agreement, as amended, provides a credit facility to the Company of  up to $5.0 million which bears interest at the higher of (i) the  prime rate plus 1.75% or (ii) 5.25% percent, plus the payment of  certain fees and expenses (the &amp;#8220;Facility&amp;#8221;).&lt;/font&gt; The  Facility is secured by substantially all the personal property of  the Company, including its accounts receivable and intellectual  property. Subject to the terms of the Financing Agreement, as  amended, availability under the Facility is based on a formula  pursuant to which Bridge Bank would advance an amount equal to the  lower of $&lt;font style=" FONT-SIZE: 10pt"&gt;5.0&lt;/font&gt; million or  &lt;font style=" FONT-SIZE: 10pt"&gt;80&lt;/font&gt;% of the Company&amp;#8217;s  eligible accounts receivable ($&lt;font style=" FONT-SIZE: 10pt"&gt;1.9&lt;/font&gt; million at June 30, 2013) with  account eligibility and advance rates determined by Bridge Bank in  its sole discretion. Prior to the amendment of the Amended  Financing Agreement described below, the term of the Facility was  two years and at the expiration of such term, all loan advances  under the Facility would have become immediately due and payable.  Under the Facility, the Company had outstanding borrowings of  $&lt;font style=" FONT-SIZE: 10pt"&gt;1.7&lt;/font&gt; million at June 30, 2013  and $&lt;font style=" FONT-SIZE: 10pt"&gt;2.4&lt;/font&gt; million at December  31, 2012.&lt;/div&gt;  &lt;/div&gt;        </NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>nonnum:textBlockItemType</ElementDataType><SimpleDataType>na</SimpleDataType><ElementDefenition>The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 505

 -SubTopic 10

 -Section 50

 -Paragraph 3

 -URI http://asc.fasb.org/extlink&amp;oid=6928386&amp;loc=d3e21475-112644



Reference 2: http://www.xbrl.org/2003/role/presentationRef

 -Publisher SEC

 -Name Regulation S-X (SX)

 -Number 210

 -Section 02

 -Paragraph 19, 20, 22

 -Article 5



Reference 3: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 210

 -SubTopic 10

 -Section S99

 -Paragraph 1

 -Subparagraph (SX 210.5-02.19,20,22)

 -URI http://asc.fasb.org/extlink&amp;oid=6877327&amp;loc=d3e13212-122682



</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Debt Disclosure [Text Block]</Label></Row></Rows><Footnotes /><IsEquityReport>false</IsEquityReport><ReportName>Credit Facility</ReportName><MonetaryRoundingLevel>UnKnown</MonetaryRoundingLevel><SharesRoundingLevel>UnKnown</SharesRoundingLevel><PerShareRoundingLevel>UnKnown</PerShareRoundingLevel><ExchangeRateRoundingLevel>UnKnown</ExchangeRateRoundingLevel><HasCustomUnits>true</HasCustomUnits><IsEmbedReport>false</IsEmbedReport><IsMultiCurrency>false</IsMultiCurrency><ReportType>Sheet</ReportType><RoleURI>http://www.transwitch.com/role/CreditFacility</RoleURI><NumberOfCols>1</NumberOfCols><NumberOfRows>2</NumberOfRows></InstanceReport>
