{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"UC3845BN","brand":"STMicroelectronics","brandSlug":"stmicroelectronics","productSlug":"UC3845BN","canonicalUrl":"https://icboms.com/stmicroelectronics/UC3845BN","factsUrl":"https://icboms.com/api/mcp/products/UC3845BN","rawCanonicalId":null},"summary":{"shortDescription":"STMicroelectronics UC3845BN current-mode PWM controller, 48% max duty cycle, up to 500 kHz switching, boost/flyback topology, 8-DIP through-hole package.","salesMarkdown":"## What the 48% duty cycle ceiling means for your converter The UC3845BN: Its defining parametric constraint is the 48% maximum duty cycle, which limits it to forward and flyback converters operating below the 50% mark — ruling out half-bridge and full-bridge architectures that need >50% duty on each output phase. Switching frequency runs up to 500 kHz, letting you shrink the transformer and output filter magnetics compared to 100 kHz-class controllers. The single transistor-driver output and the absence of synchronous rectification keep the bill of materials lean for sub-100 W offline supplies. ## Supply range and operating temperature The Vcc supply range spans 7.6 V to 30 V, which lets you bias the controller directly from a rectified AC rail through a dropping resistor — no separate regulated start-up supply needed.","metaTitle":"UC3845BN PWM Controller, 48% Duty Cycle","metaDescription":"STMicroelectronics UC3845BN current-mode PWM controller. 48% max duty cycle, up to 500 kHz switching, boost/flyback.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Obsolete","categoryPath":["Power Management (PMIC / Gate Driver)"],"specifications":{"Mfr":"STMicroelectronics","Series":"-","Package":"Tube","Function":"Step-Up, Step-Up/Step-Down","Topology":"Boost, Flyback","Clock Sync":"No","Output Type":"Transistor Driver","Mounting Type":"Through Hole","Output Phases":"1","Package / Case":"8-DIP (0.300\\\", 7.62mm)","Product Status":"Active","lifecycle_stage":"eol_hot","Control Features":"Frequency Control","Duty Cycle (Max)":"48%","Number of Outputs":"1","Serial Interfaces":"-","Base Product Number":"UC3845","Output Configuration":"Positive, Isolation Capable","Frequency - Switching":"Up to 500kHz","Operating Temperature":"-40°C~150°C(TJ)","Synchronous Rectifier":"No","Supplier Device Package":"8-Mini DIP","Voltage - Supply (Vcc/Vdd)":"7.6V ~ 30V"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.0800","priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/a1e92e6bbc45d0f8e3020163c44f39c7.pdf","sourceUrl":null,"alternativesUrl":"https://icboms.com/api/mcp/products/UC3845BN/alternatives.json"},"ai":{"faq":[{"question":"What is the maximum duty cycle of UC3845BN?","answer":"The maximum duty cycle is 48%, which limits the part to single-ended topologies like forward and flyback converters operating below 50% duty."},{"question":"Can UC3845BN be used in a boost converter?","answer":"Yes, the UC3845BN is listed for boost and flyback topologies. The 48% max duty cycle is sufficient for most boost converters, though designs requiring >48% duty at the input will need a different controller."},{"question":"Does UC3845BN require an external oscillator?","answer":"No, the UC3845BN has an internal oscillator whose frequency is set by an external RT/CT timing network. The part does not support clock synchronization."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/stmicroelectronics/UC3845BN","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/stmicroelectronics/UC3845BN when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-22T18:03:28.771Z","lastPublished":"2026-07-22T18:03:28.771Z","indexable":true}}