{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"L4985B","brand":"STMicroelectronics","brandSlug":"stmicroelectronics","productSlug":"L4985B","canonicalUrl":"https://icboms.com/stmicroelectronics/L4985B","factsUrl":"https://icboms.com/api/mcp/products/L4985B","rawCanonicalId":null},"summary":{"shortDescription":"STMicroelectronics L4985B, CCM PFC Controller, Continuous Conduction (CCM) mode, 130kHz switching frequency, 10V ~ 24.5V supply, 400µA startup, –40°C ~ 150°C junction, 8-SOIC package, Tube, Surface Mount, ROHS3 Compliant, Active.","salesMarkdown":"The STMicroelectronics L4985B is a continuous-conduction-mode (CCM) power-factor-correction (PFC) controller designed for AC-DC power supplies that need to meet harmonic-current limits. It operates at a fixed 130 kHz switching frequency and runs from a 10 V to 24.5 V supply rail, making it a straightforward fit for boost-type PFC stages in offline supplies from a few hundred watts up toward 1 kW and beyond, depending on the external MOSFET and inductor chosen. ## Key ratings that drive the design The 130 kHz switching frequency is a fixed oscillator — no external timing resistor or capacitor, which saves a pin and a couple of passives on the board. At this frequency the inductor is small enough for a compact layout but the switching losses in the MOSFET and diode still need to be budgeted; plan for a fast-recovery diode and a MOSFET with low gate charge. Startup current is 400 µA, which is low enough that a small-value resistor from the rectified DC bus can charge the VCC capacitor without excessive dissipation during startup. Once running, the controller takes its bias from the PFC output or an auxiliary winding. The junction temperature rating goes to 150°C, so this controller can live on the same hot side of the board as the power stage without needing a separate cool island. In a sealed or fanless enclosure that thermal headroom matters. ## Package and mounting No exposed pad to worry about, so the rework cycle is straightforward.","metaTitle":"STMicroelectronics L4985B CCM PFC Controller, 130 kHz","metaDescription":"STMicroelectronics L4985B CCM PFC controller in 8-SOIC. 130 kHz switching, 10V–24.5V supply, 400 µA startup, –40°C to 150°C junction. Active, RoHS3.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":"ROHS3 Compliant","productStatus":"Active","categoryPath":["DC-DC Power Modules"],"specifications":{"Mode":"Continuous Conduction (CCM)","Package":"Tube","Mounting Type":"Surface Mount","Package / Case":"8-SOIC (0.154\\\", 3.90mm Width)","lifecycle_stage":"eol_hot","Voltage - Supply":"10V ~ 24.5V","Current - Startup":"400 µA","Frequency - Switching":"130kHz","Operating Temperature":"-40°C ~ 150°C (TJ)","Supplier Device Package":"8-SO"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$2.89","stockQuantity":0,"priceTiers":[{"qty":1,"price":"$2.89000","currency":"USD"},{"qty":10,"price":"$2.59800","currency":"USD"},{"qty":25,"price":"$2.45120","currency":"USD"},{"qty":100,"price":"$2.08850","currency":"USD"},{"qty":250,"price":"$1.96100","currency":"USD"},{"qty":500,"price":"$1.71588","currency":"USD"},{"qty":1000,"price":"$1.42174","currency":"USD"},{"qty":2500,"price":"$1.32368","currency":"USD"},{"qty":5000,"price":"$1.27466","currency":"USD"}]},"links":{"datasheetUrl":"https://cdn.icboms.com/6fdf142b6403e9643710cba3d5c7c7fc.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the maximum switching frequency of L4985B?","answer":"The L4985B operates at a fixed 130 kHz switching frequency. There is no user-adjustable frequency — it is set internally."},{"question":"What is the closest pin-compatible alternative to L4985B?","answer":"The evidence does not list a pin-compatible second source or cross-reference for L4985B. For dual-sourcing options, check ST's PFC controller family in the same 8-SOIC package, but verify pin compatibility against the datasheet."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/stmicroelectronics/L4985B","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/stmicroelectronics/L4985B 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}}