PCA8525TKX - Nano-Power Automotive RTC IC, I2C | NXP
MPN: PCA8525TKX ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.95 | $1.95 |
| 10 | $1.76 | $17.60 |
| 100 | $1.52 | $152.00 |
| 500 | $1.36 | $680.00 |
| 1,000 | $1.21 | $1,210.00 |
PCA8525TKX Overview
An RTC (real-time clock) IC is a timekeeping device that maintains seconds, minutes, hours, day, weekday, month, and year information with a 32.768 kHz watch crystal. Within the power-management and timing semiconductor hierarchy, RTC ICs form a specialized subset of clock and timing ICs optimized for ultra-low standby current rather than frequency output. RTCs run continuously even when the main processor is off, so battery-backed timekeeping accuracy and supply current are their defining metrics.
Key features of the PCA8525 include nano-power supply current for extended battery life, an integrated digital temperature compensation engine that can deliver up to 5x better timekeeping accuracy than a standard uncompensated RTC, and a selectable crystal temperature model. An aging offset register further corrects long-term crystal drift, keeping timekeeping error within minutes per year rather than tens of minutes.
The compensation engine periodically measures the die temperature and digitally adjusts the clock, compensating the parabolic frequency-versus-temperature characteristic of tuning-fork crystals. Because compensation is performed on-chip, no external thermistor, lookup table, or MCU overhead is needed. The I2C interface transfers all addresses and data serially, simplifying integration with any host microcontroller.
Typical applications include automotive body control modules and gateway ECUs rated to 125 C ambient, smart meters, industrial dataloggers, and battery-powered IoT endpoints where both accuracy and nano-amp timekeeping current are critical. The automotive qualification makes it especially suitable for under-hood-adjacent modules requiring AEC-grade reliability.
Design consideration: crystal selection matters. The compensation engine assumes a typical tuning-fork crystal model; verify that the chosen crystal's curvature coefficient matches the selectable -0.035 or -0.04 ppm/degC2 setting for guaranteed accuracy.
This page synthesizes distributor sourcing data, drop-in same-family alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for PCA8525TKX — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with PCA8525TKX (same form factor and footprint) — differing in Aging Offset, Interface, Product Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PCF8525
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View Datasheet →PCA8525TK/Q900X
✅ Drop-In📋 Reference alternative (not in catalog)
PCA8525TKX Specifications
| Product Type | Real Time Clock (RTC) and calendar IC |
| Interface | I2C-bus (serial, all addresses and data) |
| Temperature Compensation | Integrated default compensation engine (crystal model selectable) |
| Crystal Curvature Coefficient Selection | -0.035 ppm/degC2 or -0.04 ppm/degC2 |
| Timekeeping Accuracy Improvement | Up to 5x vs standard uncompensated RTC |
| Crystal | External 32.768 kHz crystal required |
| Aging Offset | Supported (aging offset correction feature) |
| Operating Temperature Range | Up to +125 C (per NXP product page) |
| Package | HVSON10 |
| Mounting Type | Surface Mount |
| Automotive Qualification | Yes (automotive product, per Mouser/DigiKey listing) |
| Process Technology | CMOS |
| Sibling Part (industrial grade) | PCF8525 |
PCA8525TKX hvson10 Pin Configuration Guide
Pin configuration for PCA8525TKX (hvson10 package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for PCA8525TKX.
Refer to the datasheet for full pin configuration.
Typical Applications
PCA8525TKX is suitable for 6 applications: Automotive Body Control Modules, Smart Meters and Utility Metering, Industrial Dataloggers, Battery-Powered IoT Endpoints, Gateways and Telematics Control Units, Medical Monitoring and Diagnostic Devices.
Automotive Body Control Modules
The PCA8525TKX is explicitly positioned by NXP as an automotive high-accuracy RTC, rated up to 125 C in the HVSON10 package, which covers harsh in-vehicle zones such as engine-bay-adjacent modules and exterior lighting ECUs. Its nano-power supply current allows timekeeping from a small backup cell or supercapacitor during key-off, preserving parked-vehicle battery life. The on-chip compensation engine delivers up to 5x better accuracy than an uncompensated RTC, keeping event timestamps, diagnostic logs, and scheduled wake-ups correct across the full -40 C to +125 C automotive range without software compensation overhead. The /Q900 ordering variant supports extended automotive qualification flows for OEM traceability.
Recommended
Smart Meters and Utility Metering
Electricity, gas, and water meters must timestamp consumption events accurately for billing and tariff switching, often for 15+ years on battery or capacitor backup. The PCA8525's nano-power current draw extends backup endurance, while its integrated temperature compensation corrects the crystal's parabolic error across outdoor installations spanning -40 C to +85 C and beyond, achieving up to 5x better accuracy than an uncompensated RTC. The aging offset register compensates long-term crystal aging so that timekeeping stays within regulatory tolerance without field recalibration. The I2C interface connects directly to the metering MCU without extra glue logic, and the compact HVSON10 package fits dense meter PCBs.
Recommended
Industrial Dataloggers
Industrial condition-monitoring and process dataloggers require trustworthy timestamps for regulatory reporting and predictive maintenance analytics. The PCA8525 provides a compensated calendar with I2C access from any host controller; its temperature compensation engine, selectable between -0.035 ppm/degC2 and -0.04 ppm/degC2 crystal models, keeps timestamp error low across factory floors where ambient temperature swings between machinery bays and loading docks. Nano-power timekeeping preserves logs through power outages on a coin cell for years. With a 125 C-rated automotive-grade variant available, the same qualified design can be reused in hotter enclosures near motors and drives, reducing design fragmentation across product lines.
Recommended
Battery-Powered IoT Endpoints
Wireless sensor nodes and smart-home devices spend most of their life in deep sleep, waking on RTC interrupts to sample sensors and transmit. The PCA8525's nano-power timekeeping current means the RTC contributes negligibly to average power, maximizing battery life. Its compensated accuracy ensures scheduled wake-ups and time-stamped events remain correct even across seasonal temperature cycles that would push an uncompensated crystal tens of minutes off per year. The I2C interface shares the bus with the sensor set, and the HVSON10 surface-mount package suits compact node designs. Designers must match the crystal's curvature coefficient to the selectable compensation model for guaranteed accuracy in the field.
Recommended
Gateways and Telematics Control Units
Vehicle telematics and fleet-management gateways need accurate real-time clocks for geofencing logs, driver-hours records, and offline event buffering when GNSS time is unavailable. The PCA8525, rated to 125 C in HVSON10 with automotive targeting, keeps time in under-dash and near-engine environments while drawing nano-power current from the backup source during parking. Temperature compensation provides up to 5x better accuracy than an uncompensated RTC, minimizing drift during multi-week parking periods. Time is read over I2C by the telematics MCU to discipline timestamps when the network is down; the /Q900 variant supports extended qualification documentation for OEM release.
Recommended
Medical Monitoring and Diagnostic Devices
Portable patient monitors, infusion pumps, and home diagnostic devices must timestamp therapy events and measurement records accurately for clinical traceability. The PCA8525's nano-power consumption lets a small backup cell maintain clock operation through battery swaps and transport, while the compensation engine holds timestamp accuracy across the temperature range encountered in ambulances, wards, and storage, delivering up to 5x better accuracy than an uncompensated RTC. Data and configuration are accessed over the standard I2C bus. For non-implantable, non-life-critical equipment, the PCF8525 family sibling offers the same functionality at standard temperature grade; verify the medical device risk assessment before substitution.
Recommended
Recommended Products Summary
Engineering reference data for PCA8525TKX — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PCF8525 | PCA8525TK/Q900X |
|---|---|---|---|
| Package | HVSON10 | HVSON10 - same | HVSON10 - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Temperature Compensation | Integrated, -0.035/-0.04 ppm/degC2 selectable | Integrated, -0.035/-0.04 ppm/degC2 selectable | Integrated, -0.035/-0.04 ppm/degC2 selectable |
| Accuracy vs Uncompensated RTC | Up to 5x better | Up to 5x better | Up to 5x better |
| Qualification Target | Automotive | Standard/industrial | Extended automotive (/Q900) |
| Interface | I2C | I2C | I2C |
| Crystal | External 32.768 kHz | External 32.768 kHz | External 32.768 kHz |
Key Differentiators
- Default on-chip temperature compensation engine (vs PCF8525 (and all uncompensated RTCs))
- Automotive-grade 125 C rating (vs PCF8525)
- Selectable crystal compensation model (vs Fixed-compensation competitors such as DS3231 (crystal-on-chip approach))
Design Notes
The temperature compensation engine assumes a typical tuning-fork crystal model selectable between -0.035 ppm/degC2 and -0.04 ppm/degC2. Verify your crystal's published curvature coefficient and configure the matching setting during initialization; using the wrong model reduces the promised 5x accuracy gain toward uncompensated performance. Also apply the aging offset register based on the crystal manufacturer's aging specification to correct long-term drift.
The PCA8525 is a nano-power device, so board leakage can dominate backup current. Use low-leakage ceramic load capacitors on OSCI/OSCO, keep the I2C pull-up resistors fed from the switched main rail rather than the backup rail, and isolate the backup supply with a low-leakage diode or ideal-diode circuit. Verify total backup current budget against your cell datasheet for the target service life.
Place the 32.768 kHz crystal within a few millimeters of the OSCI/OSCO pins with short, symmetric traces. Route the crystal traces away from I2C SCL/SDA lines and any switching regulator loops, since 32 kHz tuning-fork crystals are easily disturbed by coupled noise, causing frequency offsets or startup failures. Follow the layout guidance in the NXP PCA8525 datasheet application section.
Compliance Information
NXP and distributor listings identify PCA8525TKX as an automotive product; the /Q900 ordering code targets extended automotive qualification. Explicit RoHS/REACH/halogen-free declarations were not present in the verified web data - confirm on the official NXP compliance page.
