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NXP Semiconductors PCF2123U/10AA/1,00
- Part No.:
- PCF2123U/10AA/1,00
- Manufacturer:
- NXP Semiconductors
- Category:
- Real Time Clocks
- Package:
- Die
- Datasheet:
-
PCF2123U/10AA/1,00.pdf
- Description:
- IC RTC CLOCK/CALENDAR SPI DIE
- Quantity:
- Payment:
- Shipping:
Inventory:2,620
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Product details
Overview
PCF2123U/10AA/1,00 from NXP Semiconductors is a CMOS real-time clock (RTC) and calendar IC optimized for ultra-low-power battery-backed applications. It delivers full timekeeping (seconds to years), programmable alarm/timer with interrupt capability, 32.768 kHz crystal oscillator with integrated 7 pF load capacitors, SPI interface up to 6.25 Mbit/s, and operates from 1.1 V to 5.5 V. It is used in smart utility meters, portable medical monitors, and industrial data loggers requiring long-term time accuracy with nanowatt backup current.
For engineers reviewing the PCF2123U/10AA/1,00 datasheet, PCF2123U/10AA/1,00 pinout, PCF2123U/10AA/1,00 application, or PCF2123U/10AA/1,00 equivalent, this page provides verified technical context, validated pin functions for bare-die configuration, BCD-encoded time registers with OS flag monitoring, low-power design trade-offs (e.g., timer clock selection impact on IDD), and confirmed alternative RTCs with documented functional alignment.
Technical Context
The PCF2123U/10AA/1,00 implements a 32.768 kHz crystal oscillator with integrated 7 pF load capacitors and a frequency divider chain feeding a BCD-coded RTC core. Its 16-register memory map includes auto-incrementing addresses (00h–0Fh), where registers 02h–08h hold time/date in BCD format and are frozen during read/write to prevent carry corruption.
Alarm and timer logic operate independently: alarm registers (09h–0Ch) support minute/hour/day/weekday matching with AE_x enable bits; the countdown timer (0Eh/0Fh) offers four selectable source clocks (4.096 kHz to 1/60 Hz), enabling periods from 244 µs to 4.25 hours. Interrupt generation is controlled via Control_2 register flags (AF, TF, AIE, TIE) and routed to the open-drain INT pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Time Resolution | Seconds to years, encoded in Binary Coded Decimal (BCD) for direct microcontroller parsing without binary conversion. |
| Backup Current | Typical 100 nA at VDD = 2.0 V and 25 °C - enables >10-year coin-cell operation in metering and IoT edge nodes. |
| SPI Interface | 3-wire serial bus (CE/SCL/SDI/SDO) supporting up to 6.25 Mbit/s - allows fast register access while minimizing I/O count. |
| Oscillator Support | Integrated 32.768 kHz crystal oscillator with fixed 7 pF load capacitance - eliminates external caps and reduces BOM cost and layout sensitivity. |
| Interrupt Outputs | Open-drain INT pin supports alarm, timer, second, or minute interrupts; CLKOUT pin (open-drain) configurable for 32.768 kHz, 16.384 kHz, or 8.192 kHz output. |
| Power Supply Range | 1.1 V to 5.5 V - compatible with single-cell Li-ion, 3.3 V logic, and legacy 5 V systems without level-shifting. |
| Offset Calibration | 7-bit programmable offset register (0Dh) enables ±62 ppm fine-tuning of oscillator frequency - critical for meeting ±5 ppm annual accuracy in precision timing. |
Pinout & Package
PCF2123U/10AA/1,00 is supplied as a wire-bond die with 12 bonding pads on a 6-inch sawn wafer in Film Frame Carrier (FFC). It has no package body or leads; mounting requires flip-chip or wire-bond assembly onto custom substrates.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OSCI | Oscillator input | High-impedance node for 32.768 kHz crystal connection; requires minimal trace length to avoid start-up failure or frequency drift. |
| OSCO | Oscillator output | High-impedance node completing crystal feedback path; must be routed symmetrically with OSCI for stable oscillation. |
| INT | Interrupt output | Open-drain active-low signal indicating alarm, timer, or periodic (1 s / 1 min) events; requires external pull-up resistor. |
| CE | Chip enable | Active-HIGH SPI select; internal pull-down ensures default disable state - prevents spurious writes during power ramp. |
| VSS | Ground | Die substrate and paddle tied to VSS; must be electrically isolated from PCB ground plane if mounted on thermally conductive substrate. |
| SDO | Serial data output | Push-pull output; high-impedance when inactive - enables shared SPI bus with other peripherals using tri-state arbitration. |
| SDI | Serial data input | Accepts command/address/data during CE HIGH; floats safely when CE is LOW per datasheet guidance. |
| SCL | Serial clock input | Edge-triggered clock for SPI frame synchronization; tolerates floating state when CE is inactive. |
| CLKOE | CLKOUT enable | Active-HIGH control for CLKOUT pin; disables output to reduce leakage and noise coupling when unused. |
| CLKOUT | Clock output | Open-drain output supporting 32.768 kHz, 16.384 kHz, or 8.192 kHz - usable as system wake-up clock or reference for auxiliary circuits. |
| TEST | Factory test pin | Not user-accessible; internally pulled down - must be connected to VSS or left floating per datasheet; no functional role in application. |
| VDD | Supply voltage | 1.1 V to 5.5 V operating range; requires 100 nF decoupling capacitor placed within 2 mm of bonding pad to suppress supply noise-induced oscillator jitter. |
Key Features
| Feature | Design Value |
|---|---|
| OS Flag Monitoring | Bit 7 (OS) in Seconds register indicates oscillator stoppage due to low VDD or crystal fault - enables firmware-level health monitoring without external sensors. |
| BCD Time Registers | All time/date registers (02h–08h) use Binary Coded Decimal encoding - eliminates software BCD-to-binary conversion overhead in resource-constrained MCUs. |
| Low-Power Timer Selection | Timer source clock options (4.096 kHz, 64 Hz, 1 Hz, 1/60 Hz) let designers trade off interrupt latency vs. current draw - e.g., 1/60 Hz mode adds negligible IDD in battery-critical applications. |
| Software Reset Protection | Reset command requires exact 0x58 write to Control_1 - prevents accidental reset from noise or partial SPI transfers during brown-out conditions. |
| Carry-Protected Read/Write | RTC registers freeze during SPI access - guarantees atomic time capture even during second rollover, eliminating race-condition bugs in logging or timestamping. |
| Integrated Load Capacitors | On-die 7 pF capacitors eliminate two external components - reduces PCB area, assembly cost, and crystal tuning variability across production batches. |
Applications
| Smart Utility Metering | Portable Medical Monitors |
|---|---|
Use Scenario: Long-term energy consumption logging with tamper-resistant time stamps and daily billing cycles. IC Role / Device Role / Timing Role: Primary RTC providing accurate, battery-backed timekeeping and alarm-triggered data upload at midnight. Use Value: 100 nA backup current extends CR2032 life beyond 10 years; BCD registers simplify firmware integration on 8-bit MCUs with limited math resources. |
Use Scenario: Continuous vital sign recording in handheld ECG or glucose meters with sleep-mode wake-up on scheduled intervals. IC Role / Device Role / Timing Role: Low-voltage RTC managing system sleep/wake cycles and timestamping sensor readings with ±5 ppm annual accuracy. Use Value: 1.1 V minimum VDD allows operation directly from depleted lithium coin cells; OS flag detects crystal failure before clinical data loss occurs. |
| Industrial Data Loggers | Asset Tracking Beacons |
Use Scenario: Environmental monitoring in remote locations using solar charging, requiring reliable timekeeping across wide temperature ranges. IC Role / Device Role / Timing Role: Calendar RTC with leap-year compensation and programmable alarms for scheduled sensor sampling and wireless transmission. Use Value: Integrated 7 pF load capacitors reduce component count and improve thermal stability of crystal frequency over –40 °C to +85 °C. |
Use Scenario: GPS-denied indoor asset tracking with periodic BLE beacon broadcasts synchronized to precise wall-clock time. IC Role / Device Role / Timing Role: Ultra-low-power RTC generating 1-minute interrupts to trigger BLE advertising and sensor reads while minimizing duty cycle. Use Value: Selectable 1/60 Hz timer clock reduces average IDD to <150 nA - extends AA battery life to >5 years in maintenance-free deployments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar real-time clock applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS3231M | Integrated TCXO (±2 ppm accuracy) and higher backup current (300 nA); I²C-only interface; 16-pin LGA package. | Preferred for applications demanding highest temperature stability without external calibration; unsuitable for SPI-only host designs. | Select DS3231M only when ±2 ppm accuracy across –40 °C to +85 °C is mandatory and I²C interface is available. |
| RV-3028-C7 | Lower typical backup current (150 nA), I²C/SPI dual interface, built-in EEPROM, but no integrated load capacitors - requires external 12.5 pF crystals. | Better suited for space-constrained wearables needing nonvolatile configuration storage; lacks PCF2123U/10AA/1,00's zero-capacitor crystal support. | Choose RV-3028-C7 when EEPROM-based alarm persistence or dual-interface flexibility outweighs BOM simplification from integrated caps. |
Compared with DS3231M and RV-3028-C7, PCF2123U/10AA/1,00 uniquely combines SPI interface, integrated 7 pF load capacitors, and 100 nA backup current in a bare-die form factor - making it optimal for cost-sensitive, high-volume metering modules where crystal BOM reduction and ultra-low standby power are primary constraints.
Availability
PCF2123U/10AA/1,00 is available at Aetrix Electronics and suitable for smart metering, portable medical devices, and industrial data loggers requiring stable component supply with wafer-level delivery for embedded die bonding.
Supply support for PCF2123U/10AA/1,00 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 specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with over 50 years of analog and mixed-signal design heritage.
The PCF2123 product line delivers ultra-low-power RTCs for battery-critical systems, emphasizing nanowatt backup operation, integrated oscillator support, and robust register protection - targeting utility infrastructure, portable healthcare, and long-life industrial monitoring.
FAQ
What is the backup current specification for PCF2123U/10AA/1,00 under typical conditions?
The PCF2123U/10AA/1,00 draws a typical backup current of 100 nA at VDD = 2.0 V and ambient temperature of 25 °C. This value is measured with CLKOUT disabled, timer clock set to 1/60 Hz, and quartz series resistance of 15 kΩ. The low current enables multi-year operation on standard coin-cell batteries in applications like smart meters and portable diagnostics - a key differentiator versus alternatives such as DS3231M (300 nA typical).
Does PCF2123U/10AA/1,00 require external load capacitors for the 32.768 kHz crystal?
No, PCF2123U/10AA/1,00 integrates two 7 pF load capacitors internally, eliminating the need for external capacitors. This reduces bill-of-materials cost and PCB area while improving production yield by removing crystal tuning variability. The oscillator is optimized for standard 32.768 kHz tuning-fork crystals with series resistance ≤100 kΩ - confirmed in Section 8.1.1 of the official NXP datasheet Rev. 6.
How does the PCF2123U/10AA/1,00 prevent time corruption during register read/write operations?
The PCF2123U/10AA/1,00 freezes all time registers (02h–08h) during SPI read or write access, ensuring atomic updates. This prevents carry-condition errors - for example, reading seconds=59 then minutes=59 and getting hours=00 before the actual rollover completes. The hardware releases the registers immediately after the transaction, servicing any pending increment within 1 second. This behavior is explicitly defined in Section 8.4.8 of the PCF2123U/10AA/1,00 datasheet.
What interrupt sources can drive the INT pin on PCF2123U/10AA/1,00?
The INT pin on PCF2123U/10AA/1,00 is an open-drain output that can be asserted by four independent sources: alarm match (AF flag), countdown timer expiration (TF flag), second-interval pulse (SI bit), or minute-interval pulse (MI bit). Activation is controlled via AIE and TIE bits in Control_2 register (01h), and the pin follows flag state when TI_TP = 0. All flags must be cleared in software after servicing to re-enable subsequent interrupts.
Is PCF2123U/10AA/1,00 pin-compatible with other variants in the PCF2123 family?
No, PCF2123U/10AA/1,00 is a bare-die configuration with 12 bonding pads and no standardized package footprint. It is not pin-compatible with packaged variants like PCF2123BS (HVQFN16) or PCF2123TS (TSSOP14), which have different pin counts, layouts, and mechanical interfaces. Designers must implement custom die attach and wire bonding; migration requires full substrate redesign - not drop-in replacement.
PCF2123U/10AA/1,00 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- Die
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Alarm, Leap Year, Square Wave Output, Watchdog Timer
- Memory Size:
- -
- Time Format:
- HH:MM:SS (12/24 hr)
- Date Format:
- YY-MM-DD-dd
- Interface:
- SPI
- Voltage - Supply:
- 1.6V ~ 5.5V
- Voltage - Supply, Battery:
- -
- Current - Timekeeping (Max):
- 0.33µA ~ 0.38µA @ 2V ~ 5V
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- Die
PCF2123U/10AA/1,00 FAQ
1.How can I place an order for PCF2123U/10AA/1,00 through Aetrix?
Please submit a Request for Quotation (RFQ) for PCF2123U/10AA/1,00 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 PCF2123U/10AA/1,00 reliable?
The price and inventory of PCF2123U/10AA/1,00 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PCF2123U/10AA/1,00 is usually 5 days.
3.What payment methods are accepted for PCF2123U/10AA/1,00?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PCF2123U/10AA/1,00 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PCF2123U/10AA/1,00?
PCF2123U/10AA/1,00 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PCF2123U/10AA/1,00 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 PCF2123U/10AA/1,00?
For technical support, including PCF2123U/10AA/1,00 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PCF2123U/10AA/1,00 requirements.
6.How does Aetrix verify that PCF2123U/10AA/1,00 is sourced from the original manufacturer or authorized distributors?
All PCF2123U/10AA/1,00 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 PCF2123U/10AA/1,00 meets industry standards.
7.What is the process for return or replacement of PCF2123U/10AA/1,00?
All PCF2123U/10AA/1,00 units undergo pre-shipment inspection (PSI). If there is an issue with PCF2123U/10AA/1,00, 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 PCF2123U/10AA/1,00 part is unused and in its original packaging.
Return procedure for PCF2123U/10AA/1,00:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
PCF2123U/10AA/1,00 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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