{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"L4985A","brand":"STMicroelectronics","brandSlug":"stmicroelectronics","productSlug":"L4985A","canonicalUrl":"https://icboms.com/stmicroelectronics/L4985A","factsUrl":"https://icboms.com/api/mcp/products/L4985A","rawCanonicalId":null},"summary":{"shortDescription":"STMicroelectronics L4985A CCM PFC controller, Continuous Conduction (CCM) mode, 65 kHz fixed switching frequency, 10-24.5 V supply, 8-SOIC (0.154\", 3.90mm Width) surface mount package, Tape & Reel.","salesMarkdown":"## CCM PFC controller at 65 kHz — what the switching frequency means for the boost stage The L4985A is a Continuous Conduction Mode (CCM) PFC controller running a fixed 65 kHz switching frequency. CCM operation means the inductor current never falls to zero during the switching cycle, which reduces peak current stress on the boost diode and MOSFET compared to boundary-conduction mode — the trade-off is a larger boost inductor for a given power level. At 65 kHz, the switching losses in the MOSFET and boost diode are moderate, and the magnetic core size sits in a practical range for power stages up to a few hundred watts. Raising the frequency would shrink the inductor but increase the gate-drive and switching loss budget — the L4985A's 65 kHz is a balanced point for general-purpose PFC stages. ## Supply range and startup current — bias rail design constraints The L4985A operates from a 10 V to 24.5 V supply rail, which covers the common auxiliary bias voltages derived from a flyback winding or a separate bias supply. The 400 µA startup current means the VCC capacitor can charge through a high-value resistor without excessive power dissipation during the startup phase — useful for designs where the bias rail is fed from the bulk capacitor through a dropping resistor. The 150°C maximum junction temperature rating allows operation in high-ambient environments such as enclosed power supplies or industrial PFC stages where the controller sits near hot magnetics and heatsinks. The -40°C low end covers cold-start conditions in outdoor or unheated equipment. ## Package and board-fit — 8-SOIC footprint for dense PFC layouts The supplier device package is 8-SO, which is the same mechanical outline — no footprint variation between the two designations. Tape & Reel packaging suits automated pick-and-place assembly for volume production. ## Active lifecycle and compliance — no obsolescence risk for new designs ROHS3 compliance is confirmed, so the part meets the current EU restriction levels without requiring exemption tracking. For BOM planning, the active status means the part can be specified into new PFC stages without a near-term migration risk.","metaTitle":"L4985A CCM PFC Controller, 65 kHz, 8-SOIC","metaDescription":"Active L4985A CCM PFC controller, 65 kHz fixed frequency, 10-24.5 V supply, 8-SOIC. ROHS3 compliant. Quoted to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":"ROHS3 Compliant","productStatus":"Active","categoryPath":["Analog & Data Acquisition"],"specifications":{"Mode":"Continuous Conduction (CCM)","Package":"Tape & Reel (TR)","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":"65kHz","Operating Temperature":"-40°C ~ 150°C (TJ)","Supplier Device Package":"8-SO"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$3.04","stockQuantity":0,"priceTiers":[{"qty":1,"price":"$3.04000","currency":"USD"},{"qty":10,"price":"$2.72700","currency":"USD"},{"qty":25,"price":"$2.57280","currency":"USD"},{"qty":100,"price":"$2.19190","currency":"USD"},{"qty":250,"price":"$2.05808","currency":"USD"},{"qty":500,"price":"$1.80084","currency":"USD"},{"qty":1000,"price":"$1.69890","currency":"USD"}]},"links":{"datasheetUrl":"https://cdn.icboms.com/6fdf142b6403e9643710cba3d5c7c7fc.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the L4985A's operating mode and switching frequency?","answer":"The L4985A operates in Continuous Conduction Mode (CCM) at a fixed 65 kHz switching frequency. CCM means the inductor current stays above zero throughout the switching cycle, which reduces peak currents compared to boundary-mode controllers."},{"question":"Is the L4985A a drop-in replacement for the L4986B?","answer":"No — the L4986B switches at 130 kHz, double the L4985A's 65 kHz. The boost inductor, compensation network, and EMI filter are tuned to the switching frequency, so a direct swap without redesigning the magnetic and feedback components would not work. The L4985A and L4986B share the same pinout and supply range, but the frequency difference requires a board-level re-spin."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/stmicroelectronics/L4985A","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/stmicroelectronics/L4985A 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}}