{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"UC3843D8","brand":"Texas Instruments","brandSlug":"texas-instruments","productSlug":"UC3843D8","canonicalUrl":"https://icboms.com/texas-instruments/UC3843D8","factsUrl":"https://icboms.com/api/mcp/products/UC3843D8","rawCanonicalId":null},"summary":{"shortDescription":"Texas Instruments UC3843D8 current-mode PWM controller, 8-SOIC package, up to 500 kHz switching frequency, 97% maximum duty cycle, 12 V to 28 V supply, commercial temperature range 0°C to 70°C.","salesMarkdown":"## Current-mode PWM controller for multi-topology power supplies The Texas Instruments UC3843D8 is a current-mode PWM controller designed for step-up, step-down, and step-up/step-down topologies including boost, buck, buck-boost, flyback, and forward converters. It operates from a 12 V to 28 V supply rail and delivers a single transistor-driver output with a maximum duty cycle of 97%. The switching frequency reaches up to 500 kHz, allowing the designer to trade off transformer/inductor size against switching losses. This is a commercial-temperature-grade part (0°C to 70°C), suited for indoor power supplies, AC-DC adapters, and isolated DC-DC modules where the ambient stays within that range. A 97% maximum duty cycle is notably high for a current-mode controller. It gives the designer headroom in low-dropout or high step-down ratio designs where the on-time must stay wide even at minimum input voltage. The trade-off is that the controller does not include clock synchronization (no external sync input), so the switching frequency is set by an external RC network and runs free-running. For multi-phase or noise-sensitive systems that require phase-locked switching, a synchronizable controller would be needed. The UC3843D8 is supplied in an 8-pin SOIC package (8-SOIC, 0.154\" body width, 3.90 mm width) and ships in Tube form. The supply voltage range of 12 V to 28 V (Vcc/Vdd) means the controller needs a bias rail that stays above 12 V — it is not a wide-Vin part that starts from 5 V. The output configuration is positive and isolation-capable, so it can drive a primary-side MOSFET in an isolated flyback or forward converter with an optocoupler feedback loop. The UC3843D8 is listed as Active (current production) with ROHS3 compliance.","metaTitle":"UC3843D8 PWM Controller, 500 kHz, 97% Duty Cycle, 8-SOIC","metaDescription":"UC3843D8 current-mode PWM controller from TI. Up to 500 kHz switching, 97% max duty, multi-topology (boost/buck/flyback/forward). 8-SOIC, active, ROHS3.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":"ROHS3 Compliant","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)":"97%","Number of Outputs":"1","Serial Interfaces":"-","Base Product Number":"UC3843","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":"$1.6200","priceTiers":[{"qty":1,"price":"$1.62000","currency":"USD"},{"qty":10,"price":"$1.44800","currency":"USD"},{"qty":25,"price":"$1.37400","currency":"USD"},{"qty":100,"price":"$1.12880","currency":"USD"},{"qty":250,"price":"$1.05516","currency":"USD"},{"qty":500,"price":"$0.93248","currency":"USD"},{"qty":1000,"price":"$0.73617","currency":"USD"},{"qty":2500,"price":"$0.69450","currency":"USD"}]},"links":{"datasheetUrl":"https://cdn.icboms.com/3edad1712993fb3b1751953d793dcfb6.pdf","sourceUrl":null,"alternativesUrl":"https://icboms.com/api/mcp/products/UC3843D8/alternatives.json"},"ai":{"faq":[{"question":"What is the maximum duty cycle of UC3843D8?","answer":"The maximum duty cycle is 97%, which is high for a current-mode controller and suits low-dropout or high step-down ratio designs."},{"question":"What is the typical application of UC3843D8?","answer":"It is used as a PWM controller in boost, buck, buck-boost, flyback, and forward converters — typically in AC-DC adapters, isolated DC-DC modules, and indoor power supplies where the ambient temperature stays between 0°C and 70°C."},{"question":"What is the difference between UC3843 and UC3843D8?","answer":"The UC3843D8 is the 8-pin SOIC surface-mount variant of the UC3843 controller. The base UC3843 part number typically refers to the DIP-8 through-hole package. Functionally they are identical — same current-mode PWM architecture, same 97% duty cycle, same 500 kHz switching ceiling. The D8 suffix specifies the SOIC-8 package for surface-mount assembly."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/texas-instruments/UC3843D8","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/texas-instruments/UC3843D8 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}}