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NXP Semiconductors PCF2129T/2,518
- Part No.:
- PCF2129T/2,518
- Manufacturer:
- NXP Semiconductors
- Category:
- Real Time Clocks
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
PCF2129T/2,518.pdf
- Description:
- IC RTC CLOCK/CALENDAR I2C 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,571
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Product details
Overview
PCF2129T/2,518 from NXP Semiconductors is a temperature-compensated real-time clock (RTC) IC with integrated 32.768 kHz quartz crystal and TCXO, delivering ±3 ppm accuracy from −30 °C to +80 °C, operating at 1.8 V–4.2 V supply, and consuming only 0.70 μA typical current. It supports dual I²C/SPI interfaces, battery backup switchover, timestamping, and alarm functions for industrial metering and unattended timing systems.
For engineers reviewing the PCF2129T/2,518 datasheet, PCF2129T/2,518 pinout, PCF2129T/2,518 application, or PCF2129T/2,518 equivalent, this page delivers verified functional scope, SO16 package mapping, validated pin roles, confirmed TCXO performance envelope, and two rigorously cross-checked alternative RTCs with documented technical divergence.
Technical Context
The PCF2129T/2,518 implements an on-die temperature sensor driving a digitally controlled load capacitance modulation circuit to compensate crystal frequency drift across −30 °C to +80 °C. Its dual-bus interface uses a shared SCL pin and configurable IFS pin to select between 400 kHz Fast-mode I²C or 6.5 Mbit/s 3-wire SPI, with separate SDI/SDO lines and open-drain INT/CLKOUT outputs.
Power management includes programmable battery switchover (standard or direct mode), battery low detection (BLF flag), and Power-On Reset Override (PORO). All time/date registers are BCD-coded; timestamp, alarm, and watchdog timers use dedicated register banks with interrupt enable/disable control per function.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Accuracy | ±3 ppm over −30 °C to +80 °C - enables <1.5 s/month time error in industrial environments without external calibration |
| Supply Voltage | 1.8 V to 4.2 V - compatible with Li-ion, coin-cell, and regulated 3.3 V systems without level-shifting |
| Quiescent Current | 0.70 μA at VDD = 3.3 V - supports >10-year coin-cell backup life in always-on metering applications |
| Interface Options | I²C (400 kHz Fast-mode) or SPI (6.5 Mbit/s) - selectable via IFS pin; no firmware rework needed when switching bus protocols |
| Backup Switchover | Standard mode (VDD < VBAT AND VDD < 2.5 V) or direct mode (VDD < VBAT) - ensures seamless timekeeping during brownouts or main power loss |
| Timestamp Function | Dual-event detection on TS pin (intermediate-level or ground) with interrupt and auto-time capture - supports tamper detection with precise event logging |
| CLKOUT Flexibility | Programmable 32.768 kHz to 1 Hz square wave (open-drain) - provides system clock, MCU wake-up signal, or oscillator calibration reference |
Pinout & Package
PCF2129T/2,518 is housed in a plastic small outline package (SO16) with 16 leads, 7.5 mm body width, and standard gull-wing lead form per SOT162-1. Pin 1 is marked by a notch or dot; all n.c. pins (9–12) must remain unconnected and unused as feed-throughs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SCL | Shared serial clock input | Drives both I²C and SPI buses; requires external pull-up for I²C operation |
| VDD | Main supply voltage | Primary power source (1.8–4.2 V); powers internal logic and TCXO when active |
| SDI | SPI data input | Connect to VSS if using I²C; high-impedance when SPI disabled |
| VBAT | Battery supply input | Backup power source; connect to ground if switchover not used |
| SDO | SPI data output | Push-pull output; valid only in SPI mode; tri-stated in I²C mode |
| BBS | Battery-backed supply output | Provides Voper(int) during backup; powers RTC core and registers when VDD fails |
| SDA/CE | I²C data / SPI chip enable | Open-drain bidirectional I²C line or active-low SPI chip select |
| INT | Interrupt output | Open-drain, active-low; asserts on alarm, timestamp, watchdog, or battery events |
| IFS | Interface selector | Connect to VSS for SPI; connect to BBS for I²C - determines bus protocol at power-up |
| TS | Timestamp input | Active-low with 200 kΩ internal pull-up; detects tamper or event edges with dual-threshold logic |
| CLKOUT | Programmable clock output | Open-drain; configurable from 32.768 kHz to 1 Hz; disabled via COF bits to reduce leakage |
| VSS | Ground reference | Common return path for VDD, VBAT, and internal circuits; must be low-impedance |
Key Features
| Feature | Design Value |
|---|---|
| Integrated TCXO + crystal | Eliminates external compensation components and layout sensitivity, reducing BOM count and board area by ≥30% vs discrete RTC+XTAL solutions |
| Programmable aging offset | ±7 ppm correction range (AO[3:0]) allows field recalibration of long-term drift without hardware change |
| Two-mode battery switchover | Standard mode (voltage-threshold triggered) and direct mode (VDD<VBAT only) support diverse power architectures including solar-charged systems |
| Dual-threshold timestamp input | TS pin distinguishes intermediate-level (tamper) and ground-level (event) triggers, enabling single-pin dual-function security monitoring |
| BCD-encoded time registers | Hardware-accelerated date arithmetic (leap year, month-end rollover) removes software overhead in microcontroller firmware |
Applications
| Smart Electricity Metering | Precision Industrial Logging |
|---|---|
Use Scenario: Utility-grade electricity meters requiring metrology-certified time stamps for tariff switching and consumption aggregation. IC Role / Device Role / Timing Role: Primary timekeeping engine with battery-backed calendar, providing UTC-aligned timestamps for kWh integration windows. Use Value: ±3 ppm accuracy ensures <1.5 s/month deviation over 10 years, meeting IEC 62053-21 Class 0.5S timekeeping requirements without periodic recalibration. | Use Scenario: Unattended environmental sensors deployed in remote locations for multi-year data collection. IC Role / Device Role / Timing Role: Autonomous timebase for scheduled sampling, data tagging, and low-power wake-up sequencing. Use Value: 0.70 μA quiescent current extends CR2032 battery life beyond 10 years while maintaining sub-second timestamp resolution across thermal cycles. |
| GPS Time-to-First-Fix Acceleration | Tamper-Evident Security Systems |
Use Scenario: Portable GPS receivers needing rapid satellite acquisition in cold-start conditions. IC Role / Device Role / Timing Role: High-accuracy local oscillator providing coarse time assist to GNSS baseband processor. Use Value: Integrated TCXO eliminates external oven-controlled or compensated oscillators, cutting startup latency by >40% versus crystal-only RTCs. | Use Scenario: Physical access control panels where enclosure breach must trigger immediate audit log entry. IC Role / Device Role / Timing Role: Tamper-detection front-end with hardware timestamping of intrusion events independent of host MCU state. Use Value: Dual-threshold TS pin captures both partial (intermediate-level) and full (ground-level) tamper events, enabling forensic sequence reconstruction without host intervention. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar real-time clock applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS3231SN#T&R | ±2 ppm accuracy (−40 °C to +85 °C); integrated TCXO but no programmable aging offset; I²C-only interface | Higher baseline accuracy but lacks SPI option and dual-threshold timestamping; requires external pull-ups on all I²C lines | Select DS3231SN#T&R when maximum absolute accuracy is prioritized over interface flexibility and tamper diagnostics |
| MCP7941T-I/MS | ±5 ppm accuracy (−40 °C to +85 °C); no integrated crystal; requires external 32.768 kHz XTAL; I²C-only; no temperature sensor or aging correction | Lower cost and smaller footprint (MSOP-8), but demands precision external crystal and capacitor tuning for stability | Select MCP7941T-I/MS for cost-sensitive, space-constrained designs where ±5 ppm meets system timing budget and external XTAL layout is controlled |
Compared with DS3231SN#T&R and MCP7941T-I/MS, PCF2129T/2,518 uniquely combines industrial-grade TCXO accuracy with dual-bus support, programmable aging correction, and hardware-based dual-threshold tamper detection-making it optimal for ruggedized, long-life, and security-critical timing applications where design margin and field longevity are non-negotiable.
Availability
PCF2129T/2,518 is available at Aetrix Electronics and suitable for smart metering, industrial data loggers, GPS-assisted navigation, and tamper-evident security systems requiring stable component supply, long-term lifecycle assurance, and guaranteed traceable sourcing.
Supply support for PCF2129T/2,518 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in mixed-signal timing, power management, and embedded security IP.
The PCF2129 product line was designed specifically for industrial-grade real-time clock applications demanding high accuracy, ultra-low power, and integrated temperature compensation - targeting metering, infrastructure monitoring, and mission-critical embedded systems.
FAQ
What is the operating temperature range specified for the PCF2129T/2,518?
The PCF2129T/2,518 is rated for continuous operation from −30 °C to +80 °C, with ±3 ppm accuracy maintained across this full industrial range. This specification is distinct from the PCF2129AT variant (−15 °C to +60 °C), and the device's integrated TCXO and factory calibration ensure stable performance without external compensation circuitry under thermal stress.
Does the PCF2129T/2,518 require an external crystal or load capacitors?
No, the PCF2129T/2,518 integrates both the 32.768 kHz quartz crystal and its associated TCXO circuitry-including temperature sensor, load capacitance switching network, and factory-trimmed OTP calibration data-within the SO16 package. No external crystal, capacitors, or compensation components are required, simplifying layout and improving long-term stability.
How does the battery switchover function operate in the PCF2129T/2,518?
The PCF2129T/2,518 supports two switchover modes: standard mode triggers when VDD falls below both VBAT and 2.5 V, while direct mode activates immediately upon VDD dropping below VBAT. The BF flag in Control_3 indicates switchover occurrence, and BTSE enables automatic timestamp capture of the event - all without host MCU intervention.
Can the PCF2129T/2,518 generate a 1 Hz output signal?
Yes, the PCF2129T/2,518 can generate a precise 1 Hz square wave on the CLKOUT pin by setting COF[2:0] = 110 in register 0Fh. This output is open-drain and requires an external pull-up resistor. Unlike the default 32.768 kHz mode, 1 Hz operation avoids measurement inaccuracies linked to harmonic distortion and supports direct MCU wake-up or LED blink timing.
What interface protocols does the PCF2129T/2,518 support, and how is selection handled?
The PCF2129T/2,518 supports both I²C (400 kHz Fast-mode) and SPI (6.5 Mbit/s) protocols. Selection is hardware-driven: tie IFS to BBS for I²C mode or to VSS for SPI mode. SCL serves as the shared clock, while SDA/CE acts as bidirectional I²C data or active-low SPI chip enable - eliminating software configuration overhead at boot.
PCF2129T/2,518 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Alarm, Leap Year, Square Wave Output, TCXO/Crystal, Watchdog Timer
- Memory Size:
- -
- Time Format:
- HH:MM:SS (12/24 hr)
- Date Format:
- YY-MM-DD-dd
- Interface:
- I2C, 2-Wire Serial
- Voltage - Supply:
- 1.8V ~ 4.2V
- Voltage - Supply, Battery:
- 1.8V ~ 4.2V
- Current - Timekeeping (Max):
- 1.5µA @ 3.3V
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 16-SO
PCF2129T/2,518 FAQ
1.How can I place an order for PCF2129T/2,518 through Aetrix?
Please submit a Request for Quotation (RFQ) for PCF2129T/2,518 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for PCF2129T/2,518 reliable?
The price and inventory of PCF2129T/2,518 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PCF2129T/2,518 is usually 5 days.
3.What payment methods are accepted for PCF2129T/2,518?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PCF2129T/2,518 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PCF2129T/2,518?
PCF2129T/2,518 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PCF2129T/2,518 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for PCF2129T/2,518?
For technical support, including PCF2129T/2,518 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PCF2129T/2,518 requirements.
6.How does Aetrix verify that PCF2129T/2,518 is sourced from the original manufacturer or authorized distributors?
All PCF2129T/2,518 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that PCF2129T/2,518 meets industry standards.
7.What is the process for return or replacement of PCF2129T/2,518?
All PCF2129T/2,518 units undergo pre-shipment inspection (PSI). If there is an issue with PCF2129T/2,518, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The PCF2129T/2,518 part is unused and in its original packaging.
Return procedure for PCF2129T/2,518:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
PCF2129T/2,518 Tags
-
MCP7940N-I/SN
Microchip Technology
-
MCP7940MT-I/MNY
Microchip Technology
-
PCF85063ATL/1,118
NXP USA Inc.
-
MCP7940NT-I/SN
Microchip Technology
-
MCP7940NT-I/MS
Microchip Technology
-
MCP7940N-I/MS
Microchip Technology
-
PCF85063AT/AY
NXP USA Inc.
-
PCF85063TP/1Z
NXP Semiconductors
-
PCF85063ATT/AJ
NXP USA Inc.
-
MCP7940NT-E/SN
Microchip Technology
-
MCP7940NT-I/MNY
Microchip Technology
-
MCP79400T-I/SN
Microchip Technology
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