PCF8525-ARD - RTC Evaluation Board for PCF8525 | NXP
MPN: PCF8525-ARD β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
PCF8525-ARD Overview
A real-time clock (RTC) integrated circuit is a timing device that maintains seconds, minutes, hours, day, date, month, and year information even when the main system is powered down, typically from a small backup cell. Within the power-management and timing hierarchy, an RTC sits alongside supervisors and microcontrollers, providing a low-power calendar and alarm engine that wakes the host MCU only when needed.
Key features of the underlying PCF8525 include an internal temperature compensation engine, a first for external-crystal RTC ICs, which corrects typical crystal drift using a selectable parabolic coefficient of -0.035 ppm/C2 or -0.04 ppm/C2. This software compensation approach removes the need for an expensive temperature-compensated crystal (TCXO) or RTC module, cutting bill-of-materials cost while retaining plus or minus 30 ppm accuracy over temperature in the HVSON variant.
The Arduino-compatible (ARD) header format means the board plugs directly onto NXP FRDM development platforms and standard Arduino UNO footprints, exposing the I2C bus (SDA/SCL), power rails, and RTC interrupt outputs to the host MCU. Nano-powered operation keeps backup current extremely low, extending coin-cell life in end products.
Typical applications include evaluation of timekeeping for smart meters, battery-powered data loggers, industrial PLCs, and IoT sensor nodes where calendar and alarm functions must survive main-power loss.
When evaluating, note that accuracy depends on the chosen crystal and the compensation coefficient setting programmed over I2C, so validate across the full temperature range of your end application.
This page synthesizes distributor availability data, the NXP product page, and the PCF8525 datasheet into a single engineering reference, adding drop-in board alternatives and design guidance not found on the manufacturer site.
Drop-in alternatives for PCF8525-ARD β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PCF85063-ARD
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
PCF85263-ARD
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
PCF85363-ARD
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
PCF8523-ARD
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
PCF8525-ARD Specifications (manufacturer-published)
| Product Type | Platform Evaluation Expansion Board (Arduino-compatible) |
| Evaluated Device | PCF8525 Real-Time Clock IC |
| RTC Accuracy (HVSON variant) | Up to +/-30 ppm (temperature compensated) |
| Temperature Compensation | Internal compensation engine, selectable -0.035 ppm/C2 or -0.04 ppm/C2 crystal model |
| Interface | I2C-bus (SDA/SCL) |
| Crystal | External 32.768 kHz crystal required |
| Form Factor | Arduino (ARD) expansion header |
| Host Platform Compatibility | Arduino UNO footprint / NXP FRDM platforms |
| Backup Operation | Nano-powered RTC for coin-cell backup |
| On-board Functions | RTC calendar, alarm, interrupt outputs |
| Mounting Type | Plug-in evaluation module |
PCF8525-ARD Interfaces & Connectors
No manufacturer-published interface list is available for PCF8525-ARD. Refer to the manufacturer documentation for connector and header details.
Refer to the manufacturer documentation for the full expansion header pinout and connector pin numbering.
Typical Applications
PCF8525-ARD is suitable for 6 applications: Smart Meter Timekeeping, Battery-Powered Data Loggers, Industrial PLC and Automation Timers, IoT Sensor Nodes, Medical Monitoring Devices, POS and Payment Terminal Clocks.
Smart Meter Timekeeping
Smart meters must timestamp consumption intervals accurately for billing even through grid outages. The PCF8525-ARD lets meter designers evaluate the PCF8525, whose HVSON variant holds plus or minus 30 ppm accuracy via its internal compensation engine with selectable -0.035 or -0.04 ppm/C2 crystal models, so a standard 32.768 kHz crystal replaces a costly TCXO module. On the board, the RTC connects to the host MCU over I2C while running from nano-powered backup, so a coin cell maintains the calendar during outages. Prototyping on the Arduino header validates register configuration, alarm behavior, and backup switchover before the production PCB is laid out.
Recommended
Battery-Powered Data Loggers
Portable and remote data loggers need a calendar that survives main-battery replacement and draws almost nothing from the backup cell. The PCF8525-ARD demonstrates exactly this duty cycle: the nano-powered PCF8525 holds time from a coin cell while the logger's MCU sleeps, waking it on an RTC alarm interrupt. Because the compensation engine corrects crystal drift over the full temperature range to about plus or minus 30 ppm, logged events remain chronologically trustworthy in outdoor enclosures. Engineers use the Arduino expansion format to quickly attach the RTC to an MCU target, confirm alarm-interrupt timing on a logic analyzer, and measure real backup current before committing to a custom board.
Recommended
Industrial PLC and Automation Timers
Industrial controllers schedule maintenance windows, batch recipes, and fault logs against real-world time, so the RTC must remain accurate across wide ambient temperatures inside cabinets. The PCF8525-ARD lets PLC designers evaluate the compensation engine that gives the PCF8525 HVSON variant up to plus or minus 30 ppm accuracy, roughly 5x better than uncompensated RTC ICs, without adding a TCXO. The I2C interface integrates with any PLC front-end MCU, and alarm outputs can sequence wake events. Running the board on an FRDM carrier lets firmware teams validate register maps and interrupt behavior over temperature chambers before production qualification.
Recommended
IoT Sensor Nodes
Battery-operated IoT nodes maximize life by duty-cycling the radio and MCU, waking on precise RTC alarms to sample and transmit. The PCF8525-ARD demonstrates how the nano-powered PCF8525 supplies those alarms while sipping microamp-level backup current, and its compensation engine keeps wake schedules aligned to true time within plus or minus 30 ppm over temperature. Nodes using a plain crystal RTC drift minutes per year, corrupting cloud-side event ordering; the compensated PCF8525 avoids this. Prototyping on the Arduino header lets firmware developers validate the I2C command sequence for setting alarms and confirm measured sleep current with a source meter before layout.
Recommended
Medical Monitoring Devices
Patient monitors, infusion logs, and wearable diagnostic recorders must attach a legally defensible timestamp to every measurement. The PCF8525-ARD supports evaluation of the PCF8525's plus or minus 30 ppm compensated timekeeping, which limits timestamp drift to roughly 16 minutes per year even before periodic cloud resynchronization, and its nano-powered backup preserves the clock through battery swaps. Designers prototype the I2C register configuration and alarm-driven sampling on the Arduino expansion header, then measure real backup current to predict coin-cell service life. The temperature compensation engine keeps accuracy stable against skin-temperature and ambient swings that would de-tune an uncompensated crystal clock.
Recommended
POS and Payment Terminal Clocks
Point-of-sale terminals and fiscal printers must stamp transactions with correct local time for receipts and tax compliance, even after overnight power-down. The PCF8525-ARD lets terminal designers evaluate how the nano-powered PCF8525 keeps the calendar alive from a coin cell and how its compensation engine bounds drift to plus or minus 30 ppm in the HVSON variant, avoiding the minute-per-month errors of uncompensated RTCs that frustrate auditors. The I2C interface connects cleanly to the terminal's main MCU, and alarm outputs support nightly report generation. The Arduino-compatible header enables rapid integration testing with the production firmware stack.
Recommended
Recommended Products Summary
Engineering reference data for PCF8525-ARD β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PCF85063-ARD | PCF85263-ARD | PCF85363-ARD |
|---|---|---|---|---|
| Package / Form Factor | ARD (Arduino expansion) board | ARD (Arduino expansion) board - same | ARD (Arduino expansion) board - same | ARD (Arduino expansion) board - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Evaluated RTC | PCF8525 | PCF85063 | PCF85263 | PCF85363 |
| Interface | I2C | I2C | I2C | I2C |
| Crystal Requirement | External 32.768 kHz | External 32.768 kHz | External 32.768 kHz | External 32.768 kHz |
| Backup Power Design | Nano-powered RTC | Nano-powered RTC | Nano-powered RTC | Nano-powered RTC |
Key Differentiators
- Temperature-compensated accuracy without a TCXO (vs PCF85063-ARD)
- First external-crystal RTC with default compensation engine (vs PCF8523-ARD)
- Selectable crystal drift model (vs PCF85263-ARD)
Design Notes
The PCF8525's compensation engine depends on the crystal's parabolic drift coefficient. The datasheet allows selecting between -0.035 ppm/C2 and -0.04 ppm/C2 models; using the wrong coefficient for your actual crystal degrades the realized accuracy well short of the plus or minus 30 ppm headline figure. Obtain the crystal's load capacitance and curvature specification from its own datasheet before programming the compensation registers over I2C on the PCF8525-ARD.
The RTC's nano-powered backup behavior is the main selling point, so measure backup current on the evaluation board with a microammeter or source-meter unit rather than trusting typical values. Verify that the coin-cell holder, any supervisory diodes, and leakage on the Arduino carrier do not dominate the RTC's own draw, since even a few hundred nanoamps of board leakage can shorten a CR2032 backup life from years to months.
When translating the PCF8525-ARD reference circuit into production layout, keep the 32.768 kHz crystal traces short and guard them with ground, since crystal nodes are high-impedance and susceptible to coupling from the I2C bus and nearby switching regulators. Place I2C pull-up resistors close to the bus master and size them for the bus capacitance; long Arduino-style headers add significant capacitance that slows SDA edges.
Compliance Information
Verified web data did not include explicit compliance declarations for the PCF8525-ARD board; check the NXP or distributor product page for RoHS certificates.
