{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"4N28FM","brand":"onsemi","brandSlug":"onsemi","productSlug":"4N28FM","canonicalUrl":"https://icboms.com/onsemi/4N28FM","factsUrl":"https://icboms.com/api/mcp/products/4N28FM","rawCanonicalId":null},"summary":{"shortDescription":"onsemi 4N28FM single-channel optoisolator, DC input, transistor with base output, 7500Vpk isolation, 10% min CTR at 10mA, 6-SMD Gull Wing package, Tube.","salesMarkdown":"The 4N28FM: Its primary job is to pass a DC signal across a galvanic isolation barrier while blocking ground loops and high-voltage transients. The 7500Vpk isolation voltage is the headline rating — this part creates a safety barrier rated for that peak voltage between input and output. In a motor drive or industrial PSU, that margin covers repetitive switching transients on the 400V bus without creeping into breakdown territory. Minimum current transfer ratio of 10% at 10mA forward current means the output transistor conducts at least 1mA collector current when the LED is driven at 10mA. That sets the minimum LED drive current needed to guarantee a logic-level output into a 10kΩ pull-up — budget 15-20mA forward current for margin across temperature and CTR degradation over life. Turn-on and turn-off times are both 2µs typical — this is a general-purpose isolator for low-frequency signals (DC to about 100kHz). It is not rated for high-speed data isolation; use a digital isolator or high-speed optocoupler for CAN, SPI, or Ethernet isolation. ## Temperature range and package — board-fit for harsh environments Operating temperature spans -55°C to 100°C, covering the full industrial and military temperature band. The 100°C upper limit is the junction temperature — in a sealed enclosure with 85°C ambient, the self-heating from the LED and output transistor adds about 10-15°C, keeping the junction below the 100°C ceiling with margin. The 6-SMD Gull Wing package has a seated height of approximately 3.5mm and a 0.050-inch (1.27mm) lead pitch. The Gull Wing footprint is standard for this class — the same pad layout serves the 4N25, 4N35, and 4N37 families, so a single PCB footprint covers multiple second-source options. Supplied in Tube packaging — 50 units per tube typical for this package. For volume production, confirm the tube quantity matches the pick-and-place feeder setup; the tube orientation (pin 1 at the tube stop) is standard for 6-SMD Gull Wing parts. ## Lifecycle reality — obsolete, no direct successor The 4N28FM is marked Obsolete by onsemi. For existing BOM lines, the functional replacement is a different part number — typically a 4N25, 4N35, or 4N37 variant in the same 6-SMD Gull Wing package, but with different CTR and Vce ratings. A board spin is not required, but the CTR bin and Vce(sat) must be re-verified against the circuit's minimum collector current requirement. Sourced through independent surplus and excess-inventory channels. Availability is lot-specific — date-code spread and quantity confirmed at RFQ.","metaTitle":"onsemi 4N28FM Optoisolator, 7500Vpk, 6-SMD Gull Wing","metaDescription":"onsemi 4N28FM single-channel optoisolator, 7500Vpk isolation, 10% min CTR, 2µs switching, -55°C to 100°C, 6-SMD Gull Wing.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Obsolete","categoryPath":["Optoisolators"],"specifications":{"Mfr":"onsemi","Series":"-","Package":"Tube","Input Type":"DC","Output Type":"Transistor with Base","Mounting Type":"Surface Mount","Package / Case":"6-SMD, Gull Wing","Product Status":"Obsolete","lifecycle_stage":"eol_hot","Number of Channels":"1","Base Product Number":"4N28","Voltage - Isolation":"7500Vpk","Vce Saturation (Max)":"500mV","Operating Temperature":"-55°C ~ 100°C","Rise / Fall Time (Typ)":"-","Voltage - Output (Max)":"30V","Supplier Device Package":"6-SMD","Current - Output / Channel":"-","Current Transfer Ratio (Max)":"-","Current Transfer Ratio (Min)":"10% @ 10mA","Voltage - Forward (Vf) (Typ)":"1.18V","Turn On / Turn Off Time (Typ)":"2µs, 2µs","Current - DC Forward (If) (Max)":"60 mA"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/cdfaf651d7a1a3387e48131363a5f4f6.pdf","sourceUrl":null,"alternativesUrl":"https://icboms.com/api/mcp/products/4N28FM/alternatives.json"},"ai":{"faq":[{"question":"What is the closest pin-compatible alternative to the 4N28FM?","answer":"The 4N25, 4N35, and 4N37 families in the same 6-SMD Gull Wing package share the same pinout and footprint. However, CTR and Vce(sat) ratings differ — verify the minimum collector current at the circuit's LED drive current before substituting."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/onsemi/4N28FM","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/onsemi/4N28FM when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-21T06:21:54.065Z","lastPublished":"2026-07-21T06:21:54.065Z","indexable":true}}