{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"SN74LS27D","brand":"Texas Instruments","brandSlug":"texas-instruments","productSlug":"SN74LS27D","canonicalUrl":"https://icboms.com/texas-instruments/SN74LS27D","factsUrl":"https://icboms.com/api/mcp/products/SN74LS27D","rawCanonicalId":null},"summary":{"shortDescription":"Texas Instruments 74LS series NOR Gate, SN74LS27D, 3-circuit 3-input, 14-SOIC surface-mount, 4.75V-5.25V supply, 15ns propagation delay, 0°C to 70°C operating temperature, RoHS3 compliant.","salesMarkdown":"The SN74LS27D: Each of the three gates accepts three inputs and outputs a NOR result. The input thresholds are TTL-compatible: a low level below 0.8 V, a high level above 2 V. Output drive is 400 µA sourcing and 8 mA sinking — enough to feed one or two standard TTL loads but not a heavy bus or LED without a buffer. Propagation delay is 15 ns typical at 5 V with a 15 pF load — this sets the maximum toggle rate for the signal path. At 5 V the 74LS family's speed is roughly half that of the 74HC equivalent under the same load, but the LS input thresholds are a direct drop-in for legacy TTL designs that cannot tolerate the wider HC input swing. Texas Instruments lists the SN74LS27D as Active with a ROHS3 compliance status. RoHS3 compliance (ROHS3 Compliant) means the part meets the EU's Restriction of Hazardous Substances directive including the four phthalates added in the 2015 amendment. ## 14-SOIC board-fit note The supplier device package is also 14-SOIC — no second package variant exists under this order code. For a -40°C to +85°C requirement, the 74HC family (SN74HC27APWR or SN74HC27NS) is the closer fit, though it operates from a wider 2 V to 6 V supply and uses CMOS input thresholds rather than TTL. ## Cross-reference check — 74LS vs 74HC The SN74LS27D is pin-compatible with the 74HC27 variants (SN74HC27APWR, SN74HC27NS) — same 14-SOIC footprint, same triple 3-input NOR function. The key differences are supply voltage range (74LS: 4.75 V–5.25 V; 74HC: 2 V–6 V), input thresholds (TTL levels vs CMOS levels), and temperature grade (0°C–70°C vs -40°C–85°C). A board designed for the 74LS27 will accept the 74HC27 without rewiring, but the HC part's wider input swing may not recognise a marginal TTL-high signal as a logic '1'.","metaTitle":"SN74LS27D Texas Instruments 74LS NOR Gate, 3-Input, 14-SOIC","metaDescription":"SN74LS27D active NOR gate from TI 74LS series. 3 circuits, 3 inputs each, 4.75V-5.25V supply, 15ns propagation delay at 5V/15pF. 14-SOIC package.","metaKeywords":null},"attributes":{"series":"74LS","packageCase":null,"mountingType":null,"rohsStatus":"ROHS3 Compliant","productStatus":"Active","categoryPath":["Discrete Semiconductors"],"specifications":{"Series":"74LS","Package":"Tube","Logic Type":"NOR Gate","Mounting Type":"Surface Mount","Package / Case":"14-SOIC (0.154\\\", 3.90mm Width)","lifecycle_stage":"eol_hot","Number of Inputs":"3","Voltage - Supply":"4.75V ~ 5.25V","Number of Circuits":"3","Operating Temperature":"0°C ~ 70°C","Input Logic Level - Low":"0.8V","Supplier Device Package":"14-SOIC","Input Logic Level - High":"2V","Current - Quiescent (Max)":"4 mA","Current - Output High, Low":"400µA, 8mA","Max Propagation Delay @ V, Max CL":"15ns @ 5V, 15pF"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.4","stockQuantity":0,"priceTiers":[{"qty":1,"price":"$1.40000","currency":"USD"},{"qty":10,"price":"$1.25400","currency":"USD"},{"qty":25,"price":"$1.19000","currency":"USD"},{"qty":100,"price":"$0.97760","currency":"USD"},{"qty":250,"price":"$0.91388","currency":"USD"},{"qty":500,"price":"$0.80762","currency":"USD"},{"qty":1000,"price":"$0.63759","currency":"USD"},{"qty":2500,"price":"$0.60150","currency":"USD"}]},"links":{"datasheetUrl":"https://cdn.icboms.com/eed22ddee164dfed8d0f4abfa2cc7c13.pdf","sourceUrl":null},"ai":{"faq":[{"question":"Can SN74LS27D replace SN74HC27APWR on the same board?","answer":"The SN74LS27D is pin-compatible with the SN74HC27APWR — same 14-SOIC footprint and same triple 3-input NOR logic. However, the 74LS part requires a 5 V ±5 % supply (4.75 V–5.25 V) while the 74HC part operates from 2 V to 6 V. The 74LS input thresholds are TTL-compatible (low < 0.8 V, high > 2 V), whereas the 74HC thresholds follow CMOS ratios. A board designed for the 74HC27 may accept the 74LS27 if the supply is 5 V and the input levels meet TTL specs, but the reverse substitution — dropping a 74HC27 into a 74LS socket — risks logic-level mismatch if the driving gate outputs a marginal TTL-hi"},{"question":"What is the propagation delay of SN74LS27D?","answer":"The maximum propagation delay is 15 ns at 5 V with a 15 pF load. This is typical for the 74LS family and sets the data-rate ceiling for the signal path — roughly half the speed of a 74HC27 under the same load."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/texas-instruments/SN74LS27D","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/texas-instruments/SN74LS27D when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-22T19:45:10.375Z","lastPublished":"2026-07-22T19:45:10.375Z","indexable":true}}