{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"PCF2129T/2,518","brand":"NXP Semiconductors","brandSlug":"nxp","productSlug":"PCF2129T-2518","canonicalUrl":"https://icboms.com/nxp/PCF2129T-2518","factsUrl":"https://icboms.com/api/mcp/products/PCF2129T%2F2%2C518","rawCanonicalId":null},"summary":{"shortDescription":"NXP Semiconductors PCF2129T/2,518 Clock/Calendar RTC, I2C 2-Wire Serial, 1.8V-4.2V, -40°C to 85°C, 16-SOIC (0.295\", 7.50mm Width), Tape & Reel (TR); Cut Tape (CT).","salesMarkdown":"## Active I2C RTC with integrated TCXO — what the 1.5 µA timekeeping figure means for battery life The PCF2129T/2,518: A CR2032 rated 225 mAh delivers roughly 150,000 hours (17 years) of backup at that draw, though self-discharge and the battery's own temperature derating will dominate in practice. The part also integrates a TCXO/crystal, alarm, leap-year tracking, square-wave output, and a watchdog timer — all on-chip, no external oscillator or compensation network needed. ## Supply voltage and temperature grade — the operating envelope for the BOM The battery backup input has the same 1.8 V to 4.2 V range, so the same cell type serves both main and backup roles — no voltage translation between the two. For a data logger in an outdoor cabinet or a telematics unit under the dashboard, the RTC keeps time across the full thermal excursion without a separate temperature-compensated crystal. The 16-SOIC wide-body package (7.50 mm width) is a standard footprint, hand-solderable and rework-friendly, with a 1.27 mm pitch that routes cleanly on two-layer boards. ## Timekeeping and interface — what the I2C bus and date/time formats mean for firmware integration The I2C interface runs at standard (100 kHz) or fast (400 kHz) mode — the RTC shares the bus with sensors, EEPROM, or an MCU without a dedicated RTC pin. Date format is YY-MM-DD-dd; time format is HH:MM:SS with 12/24 hr selection. The firmware driver reads and writes these as BCD registers — no binary-to-decimal conversion in the application layer. The square-wave output can be programmed to 1 Hz, 4.096 kHz, 8.192 kHz, or 32.768 kHz — useful as a calibration tick for an MCU's internal RC oscillator or as a wake-up strobe for a low-power sleep cycle. The watchdog timer resets the system if the I2C host stops refreshing it within a configurable window, which catches firmware hangs in field-deployed equipment. ## Compliance and sourcing posture The PCF2129T/2,518 is ROHS3 compliant — no exemption-based conflict with EU, UKCA, or China RoHS.","metaTitle":"NXP PCF2129T/2,518 I2C RTC, 1.5 µA, 16-SOIC","metaDescription":"NXP PCF2129T/2,518 real-time clock/calendar, I2C interface, 1.5 µA timekeeping at 3.3 V, -40 to +85 °C, 16-SOIC. Active production, ROHS3. Quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":"ROHS3 Compliant","productStatus":"Active","categoryPath":["Microcontrollers & Processors (MCU / MPU / DSP)"],"specifications":{"Type":"Clock/Calendar","Package":"Tape & Reel (TR); Cut Tape (CT)","Features":"Alarm, Leap Year, Square Wave Output, TCXO/Crystal, Watchdog Timer","Interface":"I2C, 2-Wire Serial","Date Format":"YY-MM-DD-dd","Time Format":"HH:MM:SS (12/24 hr)","Mounting Type":"Surface Mount","Package / Case":"16-SOIC (0.295\\\", 7.50mm Width)","lifecycle_stage":"eol_hot","Voltage - Supply":"1.8V ~ 4.2V","Operating Temperature":"-40°C ~ 85°C","Supplier Device Package":"16-SO","Voltage - Supply, Battery":"1.8V ~ 4.2V","Current - Timekeeping (Max)":"1.5µA @ 3.3V"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$6.19","stockQuantity":0,"priceTiers":[{"qty":1,"price":"$6.19000","currency":"USD"},{"qty":10,"price":"$5.59100","currency":"USD"},{"qty":25,"price":"$5.33080","currency":"USD"},{"qty":100,"price":"$4.62860","currency":"USD"},{"qty":250,"price":"$4.42060","currency":"USD"},{"qty":500,"price":"$4.03054","currency":"USD"},{"qty":1000,"price":"$3.51047","currency":"USD"},{"qty":2000,"price":"$3.38045","currency":"USD"}]},"links":{"datasheetUrl":"https://cdn.icboms.com/de6be08b76d59afbe29afad204ec4f63.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the timekeeping current draw of PCF2129T/2,518 at 3.3 V?","answer":"The maximum timekeeping current is 1.5 µA at 3.3 V. This is the current drawn from the battery supply while the main system power is off, and it determines the backup runtime from a coin cell."},{"question":"What package does PCF2129T/2,518 come in?","answer":"The supplier device package is 16-SO. It is available in Tape & Reel (TR) or Cut Tape (CT) options."},{"question":"What compliance documentation does NXP provide for PCF2129T/2,518?","answer":"The PCF2129T/2,518 is ROHS3 compliant. NXP provides the standard RoHS certificate of compliance and material declaration. No UL or IEC certification is listed in the available documentation."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/nxp/PCF2129T-2518","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/nxp/PCF2129T-2518 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-22T19:45:10.375Z","lastPublished":"2026-07-22T19:45:10.375Z","indexable":true}}