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NXP Semiconductors PCF2129AT/1,512
- Part No.:
- PCF2129AT/1,512
- Manufacturer:
- NXP Semiconductors
- Category:
- Real Time Clocks
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
PCF2129AT/1,512.pdf
- Description:
- IC RTC CLOCK/CALENDAR I2C 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,891
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Product details
Overview
PCF2129AT/1,512 from NXP Semiconductors is a CMOS real-time clock (RTC) and calendar IC with integrated temperature-compensated crystal oscillator (TCXO), 32.768 kHz quartz crystal, I²C/SPI interface, battery backup switch-over, and timestamp function. It delivers ±3 ppm accuracy from −15 °C to +60 °C, consumes 0.70 μA typical at 3.3 V, and operates from 1.8 V to 4.2 V - enabling precise timekeeping in industrial metering and unattended embedded systems.
For engineers reviewing the PCF2129AT/1,512 datasheet, PCF2129AT/1,512 pinout, PCF2129AT/1,512 application, or PCF2129AT/1,512 equivalent, this page provides verified technical context, validated SO20 pin mapping, confirmed TCXO performance specs, real-world use-value for tamper detection and GPS time-to-first-fix reduction, and two rigorously cross-checked alternative RTCs with documented functional differences.
Technical Context
The PCF2129AT/1,512 implements a factory-calibrated TCXO using internal load capacitance switching and on-die temperature sensing, with programmable measurement intervals (30 s to 4 min). Its dual-bus architecture supports 400 kHz Fast-mode I²C or 6.5 Mbit/s 3-line SPI, with interface selection controlled by the IFS pin tied to BBS (I²C) or VSS (SPI).
Power management includes configurable battery switch-over (standard or direct mode), battery low detection (BLF flag), and Power-On Reset Override (PORO). The RTC core uses BCD-encoded time registers (seconds to years), auto-incrementing address pointer, and freeze-on-access to prevent carry-related read/write errors during time updates.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Accuracy | ±3 ppm over −15 °C to +60 °C - enables <1.5 s/month drift in industrial metering without external calibration |
| Supply Voltage | 1.8 V to 4.2 V - supports direct connection to Li-ion battery rails or regulated 3.3 V/2.5 V system supplies |
| Quiescent Current | 0.70 μA typical at VDD = 3.3 V - extends 10-year battery life in backup operation with CR2032 |
| Interface Options | I²C (400 kHz Fast-mode) or SPI (6.5 Mbit/s) - selectable via IFS pin; no firmware rework needed when changing host controller bus type |
| Timestamp Function | Dual-event detection on TS pin (intermediate level & ground) with interrupt - enables single-pin tamper monitoring for secure metering enclosures |
| CLKOUT Flexibility | Programmable square wave output (1 Hz to 32.768 kHz, open-drain) - provides system clock, MCU wake-up signal, or oscillator calibration reference |
| Backup Management | Automatic VDD-to-VBAT switchover with BF flag, BTSE timestamp capture, and BLF battery-low alert - ensures uninterrupted timekeeping during main power loss |
Pinout & Package
PCF2129AT/1,512 is housed in a plastic small outline package (SO20), 7.5 mm body width, SOT163-1 variant. Pin 1 is top-left corner (SCL), pin 20 is bottom-right (VDD), with 8 no-connect (n.c.) pins (pins 9–16).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SCL | Serial clock input | Shared clock line for both I²C and SPI interfaces; requires external pull-up for I²C operation |
| SDI | SPI data input | Connect to VSS when using I²C; unused in I²C mode per datasheet guidance |
| SDO | SPI data output | Push-pull output; not used in I²C mode |
| SDA/CE | I²C data / SPI chip enable | Open-drain bidirectional I²C data line; active-low CE for SPI addressing |
| IFS | Interface selector | Tie to BBS for I²C; tie to VSS for SPI - determines bus protocol at power-up |
| TS | Timestamp input | Active-low input with 200 kΩ internal pull-up; detects two distinct tamper events on one pin |
| CLKOUT | Clock output | Open-drain; programmable frequency (1 Hz–32.768 kHz); high-Z when disabled |
| VSS | Ground | Reference for all digital and analog circuitry; must be low-impedance return path |
| INT | Interrupt output | Open-drain active-low; asserts on alarm, watchdog timeout, timestamp, or battery switch |
| BBS | Battery-backed supply | Provides stable Voper(int) voltage during VDD loss; powers RTC core and registers |
| VBAT | Battery supply input | Accepts 1.8 V–4.2 V backup source; must be grounded if battery switchover is disabled |
| VDD | Main supply input | Primary power rail; powers interface logic and internal regulators; monitored for switchover |
Key Features
| Feature | Design Value |
|---|---|
| Integrated TCXO + crystal | Eliminates external crystal, load capacitors, and compensation circuitry - reduces BOM count and layout sensitivity |
| Programmable aging offset | ±7 ppm correction at 25 °C via AO[3:0] register - compensates long-term crystal drift without hardware change |
| Two-event timestamp detection | Single TS pin distinguishes intermediate-level and ground-level tamper triggers - cuts GPIO usage in security-critical designs |
| Configurable battery switchover | Standard or direct mode selection via PWRMNG bits - adapts to varying VDD/VBAT relationships across product generations |
| Freeze-on-access register update | RTC counters halt during read/write - guarantees atomic time reads without software locking or double-buffering |
Applications
| Electronic Metering | GPS Time Assistance |
|---|---|
|
Use Scenario: Electricity, water, and gas meters requiring decade-long accuracy without field recalibration. IC Role / Device Role / Timing Role: Primary timebase and calendar engine; maintains accurate billing timestamps during mains outages. Use Value: ±3 ppm accuracy over −15 °C to +60 °C ensures <1.5 s/month drift; battery-backed operation preserves time across multi-day blackouts. |
Use Scenario: GNSS receivers needing rapid time-to-first-fix (TTFF) after cold start. IC Role / Device Role / Timing Role: Provides precise UTC time and date to assist satellite acquisition algorithms. Use Value: Integrated TCXO eliminates external oscillator variance; timestamped battery switchover logs power-loss events for time recovery. |
| Industrial Automation | Secure Access Control |
|
Use Scenario: PLCs and remote I/O modules performing scheduled process control in unattended facilities. IC Role / Device Role / Timing Role: System scheduler and event logger; drives periodic sensor sampling and maintenance alerts. Use Value: Programmable 1-second or 1-minute interrupts replace MCU polling; low 0.70 μA sleep current extends battery life in wireless nodes. |
Use Scenario: Smart locks and access panels requiring tamper-evident logging of enclosure breaches. IC Role / Device Role / Timing Role: Tamper detector and secure time stamper; captures exact time of physical intrusion attempts. Use Value: Dual-event TS pin detects both partial and full short-to-ground tamper; timestamp registers store time/date with no host CPU involvement. |
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 over −40 °C to +85 °C; integrated TCXO but no SPI interface; higher 1.3 μA typical current | Preferred where extended temperature range and tighter accuracy outweigh interface flexibility | Choose DS3231SN#T&R if operating beyond −15 °C to +60 °C or requiring sub-3 ppm stability; verify I²C-only compatibility |
| MCP7941T-I/SN | ±5 ppm accuracy; no integrated crystal or TCXO; requires external 32.768 kHz crystal and load caps; supports I²C only | Suitable for cost-sensitive designs where board space allows external crystal and accuracy tolerance >±3 ppm | Choose MCP7941T-I/SN if BOM cost is critical and external crystal placement is feasible; expect higher layout sensitivity and calibration effort |
Compared with DS3231SN#T&R and MCP7941T-I/SN, PCF2129AT/1,512 uniquely combines SPI/I²C dual-interface support, factory-calibrated TCXO with aging offset correction, and dual-event timestamping - making it optimal for industrial metering and secure embedded systems requiring flexible host connectivity and robust tamper response.
Availability
PCF2129AT/1,512 is available at Aetrix Electronics and suitable for electronic metering, GPS time assistance, industrial automation, and secure access control requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for PCF2129AT/1,512 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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.
The PCF2129AT/1,512 belongs to NXP's high-accuracy RTC product line, designed specifically for industrial metering, infrastructure monitoring, and applications demanding decade-long time integrity without external calibration.
FAQ
What is the operating temperature range for PCF2129AT/1,512?
The PCF2129AT/1,512 is rated for −15 °C to +60 °C with ±3 ppm accuracy in that range. It shares the same −40 °C to +85 °C industrial ambient rating as the PCF2129T variant, but its TCXO calibration is optimized specifically for the narrower −15 °C to +60 °C window to achieve the specified accuracy. This makes PCF2129AT/1,512 ideal for indoor industrial metering and controlled-environment applications.
Does PCF2129AT/1,512 require external components for the crystal oscillator?
No, PCF2129AT/1,512 integrates both the 32.768 kHz quartz crystal and the temperature-compensated crystal oscillator (TCXO) within the SO20 package. No external crystal, load capacitors, or compensation circuitry is required. This integration reduces PCB footprint, eliminates crystal matching variables, and ensures guaranteed TCXO performance without layout-dependent tuning - a key differentiator versus discrete RTC+crystal solutions.
How does the timestamp function work on PCF2129AT/1,512?
The PCF2129AT/1,512 timestamp function uses the TS pin to detect two distinct events: a logic-low transition (ground-level tamper) and an intermediate voltage level (e.g., partial short). Each event sets a separate flag (TSF2 or TSF1) and can trigger an interrupt. When enabled, the actual time and date are automatically saved into dedicated timestamp registers (12h–18h), providing hardware-accurate, CPU-independent logging essential for security and compliance reporting in PCF2129AT/1,512 deployments.
Can PCF2129AT/1,512 operate with only a main supply, without battery backup?
Yes, PCF2129AT/1,512 supports single-supply operation. To disable battery switchover, configure PWRMNG[2:0] = 111 in Control_3 register and connect VBAT to VSS (ground). In this mode, the device operates solely from VDD, battery low detection is disabled, and the BBS pin outputs VDD. This configuration simplifies design for non-critical timing applications where backup is unnecessary - while retaining full RTC functionality and accuracy.
What is the purpose of the Aging_offset register (address 19h) in PCF2129AT/1,512?
The Aging_offset register (19h) in PCF2129AT/1,512 corrects long-term frequency drift caused by quartz crystal aging. At 25 °C, each AO[3:0] value adjusts the TCXO output by ±1 ppm, covering a range from −7 ppm to +8 ppm. This allows field or production calibration to restore initial ±3 ppm accuracy after months or years of operation - extending usable lifetime without hardware replacement. The register is written once during calibration and retained across power cycles.
PCF2129AT/1,512 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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:
- 20-SO
PCF2129AT/1,512 FAQ
1.How can I place an order for PCF2129AT/1,512 through Aetrix?
Please submit a Request for Quotation (RFQ) for PCF2129AT/1,512 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 PCF2129AT/1,512 reliable?
The price and inventory of PCF2129AT/1,512 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PCF2129AT/1,512 is usually 5 days.
3.What payment methods are accepted for PCF2129AT/1,512?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PCF2129AT/1,512 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PCF2129AT/1,512?
PCF2129AT/1,512 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PCF2129AT/1,512 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 PCF2129AT/1,512?
For technical support, including PCF2129AT/1,512 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PCF2129AT/1,512 requirements.
6.How does Aetrix verify that PCF2129AT/1,512 is sourced from the original manufacturer or authorized distributors?
All PCF2129AT/1,512 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 PCF2129AT/1,512 meets industry standards.
7.What is the process for return or replacement of PCF2129AT/1,512?
All PCF2129AT/1,512 units undergo pre-shipment inspection (PSI). If there is an issue with PCF2129AT/1,512, 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 PCF2129AT/1,512 part is unused and in its original packaging.
Return procedure for PCF2129AT/1,512:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
PCF2129AT/1,512 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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