{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"BUL128D-B","brand":"STMicroelectronics","brandSlug":"stmicroelectronics","productSlug":"BUL128D-B","canonicalUrl":"https://icboms.com/stmicroelectronics/BUL128D-B","factsUrl":"https://icboms.com/api/mcp/products/BUL128D-B","rawCanonicalId":null},"summary":{"shortDescription":"STMicroelectronics BUL128D-B NPN power transistor, 400 V Vce breakdown, 4 A continuous collector current, 70 W max power dissipation, TO-220-3 through-hole package, active lifecycle, ROHS3 compliant.","salesMarkdown":"The STMicroelectronics BUL128D-B is a 400 V, 4 A NPN bipolar power transistor in a through-hole TO-220-3 package. ## Saturation voltage and base drive — what the numbers mean Vce(sat) is specified at 500 mV maximum with 1 A base current driving 4 A collector current.","metaTitle":"BUL128D-B NPN Power Transistor, 400 V 4 A TO-220","metaDescription":"BUL128D-B NPN bipolar transistor, 400 V Vce, 4 A Ic, 70 W in TO-220. Active, ROHS3.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":"ROHS3 Compliant","productStatus":"Active","categoryPath":["Analog & Data Acquisition"],"specifications":{"Package":"Tube","Power - Max":"70 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-220","Vce Saturation (Max) @ Ib, Ic":"500mV @ 1A, 4A","Current - Collector (Ic) (Max)":"4 A","Current - Collector Cutoff (Max)":"250µA","DC Current Gain (hFE) (Min) @ Ic, Vce":"12 @ 2A, 5V","Voltage - Collector Emitter Breakdown (Max)":"400 V"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$0.68","priceTiers":[{"qty":1,"price":"$0.68000","currency":"USD"},{"qty":10,"price":"$0.58800","currency":"USD"},{"qty":100,"price":"$0.40700","currency":"USD"},{"qty":500,"price":"$0.34008","currency":"USD"},{"qty":1000,"price":"$0.28943","currency":"USD"},{"qty":2000,"price":"$0.25777","currency":"USD"},{"qty":5000,"price":"$0.24420","currency":"USD"},{"qty":10000,"price":"$0.22611","currency":"USD"}]},"links":{"datasheetUrl":"https://cdn.icboms.com/24d6b4017f2a66738c11f90cc763ea4e.pdf","sourceUrl":null,"alternativesUrl":"https://icboms.com/api/mcp/products/BUL128D-B/alternatives.json"},"ai":{"faq":[{"question":"What is the typical hFE for BUL128D-B at 2 A?","answer":"The minimum DC current gain (hFE) is 12 at 2 A collector current with 5 V collector-emitter voltage. Typical gain will be higher, but the minimum is the figure to design the base drive around."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/stmicroelectronics/BUL128D-B","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/stmicroelectronics/BUL128D-B when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-08-11T15:49:49.435Z","lastPublished":"2026-08-11T15:49:49.435Z","indexable":true}}