{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"BUJ302A,127","brand":"NXP Semiconductors","brandSlug":"nxp","productSlug":"BUJ302A127","canonicalUrl":"https://icboms.com/nxp/BUJ302A127","factsUrl":"https://icboms.com/api/mcp/products/BUJ302A%2C127","rawCanonicalId":null},"summary":{"shortDescription":"WeEn Semiconductors BUJ302A,127 NPN power bipolar transistor, 400 V Vce breakdown, 4 A Ic, 80 W max power, TO-220-3 through-hole package, 150°C junction temperature.","salesMarkdown":"## 400 V NPN — the flyback / offline switcher transistor The WeEn Semiconductors BUJ302A,127 is a high-voltage NPN power bipolar transistor built for offline power conversion — flyback converters, switch-mode power supply front-ends, and similar circuits where the DC bus sits at 300 V to 400 V after rectification. The 400 V collector-emitter breakdown rating gives it the voltage headroom for universal-input (85–265 VAC) flyback designs with a reasonable derating margin. The 4 A continuous collector current and 80 W maximum power dissipation define the practical output power envelope: in a typical flyback at 70 kHz, this part can deliver roughly 40–60 W depending on heatsinking and ambient temperature. ## 1.5 V Vce(sat) at 3.5 A — what the on-state drop means for the BOM The saturation voltage is specified at 1.5 V maximum with a base current of 1 A and a collector current of 3.5 A. That 1.5 V drop at 3.5 A produces 5.25 W of conduction loss — the bulk of the dissipation in a hard-switched flyback. The 80 W power max is the package limit with an infinite heatsink at 25°C case temperature; real-world dissipation will be lower. The 25 minimum DC current gain at 800 mA collector current and 3 V Vce means the base drive circuit must supply at least 32 mA to saturate the transistor at 800 mA, and proportionally more at higher collector currents. ## TO-220-3 — the standard through-hole power package The BUJ302A comes in the TO-220-3 package, also designated TO-220AB. The metal tab is electrically connected to the collector, so the heatsink must be electrically isolated or the whole assembly floats. Through-hole mounting means it is a hand-solder or wave-solder part — no reflow profile needed, but the leads need to be bent and inserted before soldering. WeEn Semiconductors still manufactures this part, so there is no last-time-buy deadline or forced redesign.","metaTitle":"BUJ302A,127 NPN Power Transistor, 400 V Vce, 4 A Ic, TO-220","metaDescription":"BUJ302A,127 NPN power bipolar transistor. 400 V Vce breakdown, 4 A continuous collector current, 80 W max power in TO-220-3. Active lifecycle.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Logic ICs"],"specifications":{"Package":"Bulk","Power - Max":"80 W","Mounting Type":"Through Hole","Package / Case":"TO-220-3","Transistor Type":"NPN","lifecycle_stage":"eol_hot","Operating Temperature":"150°C (TJ)","Supplier Device Package":"TO-220AB","Vce Saturation (Max) @ Ib, Ic":"1.5V @ 1A, 3.5A","Current - Collector (Ic) (Max)":"4 A","Current - Collector Cutoff (Max)":"250mA","DC Current Gain (hFE) (Min) @ Ic, Vce":"25 @ 800mA, 3V","Voltage - Collector Emitter Breakdown (Max)":"400 V"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$0.33","stockQuantity":0,"priceTiers":[{"qty":902,"price":"$0.33000","currency":"USD"}]},"links":{"datasheetUrl":"https://cdn.icboms.com/30077818258861ee2d3f2d284d3798d6.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the BUJ302A transistor Vce and Ic specification?","answer":"The BUJ302A is rated for a 400 V collector-emitter breakdown voltage and a 4 A continuous collector current. The saturation voltage is 1.5 V maximum at 1 A base current and 3.5 A collector current."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/nxp/BUJ302A127","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/nxp/BUJ302A127 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-17T19:50:00.618Z","lastPublished":"2026-07-17T19:50:00.618Z","indexable":true}}