{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"UC3844D8","brand":"Texas Instruments","brandSlug":"texas-instruments","productSlug":"UC3844D8","canonicalUrl":"https://icboms.com/texas-instruments/UC3844D8","factsUrl":"https://icboms.com/api/mcp/products/UC3844D8","rawCanonicalId":null},"summary":{"shortDescription":"Texas Instruments UC3844D8 current-mode PWM controller, 48% max duty cycle, up to 500 kHz switching frequency, 12V–28V supply, transistor driver output, 8-SOIC package, 0°C to 70°C operating temperature.","salesMarkdown":"The Texas Instruments UC3844D8 is a current-mode PWM controller with a maximum duty cycle of 48%, intended for single-ended topologies — flyback, forward, boost, buck, and buck-boost. The 48% ceiling is the hard limit for the on-time of the external power switch; in a flyback design it sets the maximum volt-seconds the transformer can deliver before the core resets. The controller drives a single transistor output and includes frequency control for oscillator synchronisation. ## Switching frequency up to 500 kHz — transformer sizing trade-off The oscillator runs up to 500 kHz, which lets the designer shrink the magnetic components — a 200 kHz flyback transformer is about half the core volume of a 100 kHz design. The trade-off is higher switching losses in the MOSFET and snubber, so the actual frequency choice depends on the thermal budget of the power stage. The controller does not include clock synchronisation, so multiple converters on the same board must be free-run or use external sync injection. ## 12V to 28V supply rail — bias winding planning The Vcc supply range of 12V to 28V means the controller needs a regulated auxiliary winding or a separate bias supply within that window. Below 12V the undervoltage lockout holds the output off; above 28V the internal regulator clamps. In a typical offline flyback, the auxiliary winding is designed to deliver ~16V–18V after startup, which sits comfortably inside the range. The output is a single transistor driver, positive polarity, with isolation capability through an external optocoupler feedback loop.","metaTitle":"UC3844D8 Current-Mode PWM Controller, 48% Duty Cycle, 8-SOIC","metaDescription":"Texas Instruments UC3844D8 current-mode PWM controller. 48% max duty cycle, up to 500 kHz switching, 12V–28V supply. Active production.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["Power Management (PMIC / Gate Driver)"],"specifications":{"Mfr":"Texas Instruments","Series":"-","Package":"Tube","Function":"Step-Up, Step-Down, Step-Up/Step-Down","Topology":"Boost, Buck, Buck-Boost, Flyback, Forward","Clock Sync":"No","Output Type":"Transistor Driver","Mounting Type":"Surface Mount","Output Phases":"1","Package / Case":"8-SOIC (0.154\\\", 3.90mm Width)","Product Status":"Active","lifecycle_stage":"eol_hot","Control Features":"Frequency Control","Duty Cycle (Max)":"48%","Number of Outputs":"1","Serial Interfaces":"-","Base Product Number":"UC3844","Output Configuration":"Positive, Isolation Capable","Frequency - Switching":"Up to 500kHz","Operating Temperature":"0°C~70°C(TA)","Synchronous Rectifier":"No","Supplier Device Package":"8-SOIC","Voltage - Supply (Vcc/Vdd)":"12V ~ 28V"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$0.9325","priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/3edad1712993fb3b1751953d793dcfb6.pdf","sourceUrl":null,"alternativesUrl":"https://icboms.com/api/mcp/products/UC3844D8/alternatives.json"},"ai":{"faq":[{"question":"What is the maximum duty cycle of UC3844D8?","answer":"The maximum duty cycle is 48%. This is the hard ceiling for the on-time of the external power switch; it limits the output voltage range in a flyback or forward converter and is the key parametric difference from the UC3845D8, which is rated at 50%."},{"question":"What is the difference between UC3844D8 and UC3845D8?","answer":"The primary difference is the maximum duty cycle: the UC3844D8 is limited to 48%, while the UC3845D8 allows up to 50%. Both are current-mode PWM controllers in the same 8-SOIC package with the same pinout, supply range, and switching frequency. The UC3844D8 is the correct choice when the design requires a duty-cycle ceiling below 50% — typically for forward converters that need a guaranteed core-reset margin."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/texas-instruments/UC3844D8","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/texas-instruments/UC3844D8 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}}