R2223L-E2

Real Time Clock Overview

The R2223L-E2 is a CMOS real-time clock IC from Nisshinbo Micro Devices, utilizing a QFN018018-12 package. It interfaces with CPUs via a 2-wire serial bus (SCL/SDA) supporting I2C fast mode up to 400 kHz. The device provides time and calendar counters in BCD format, two alarm interrupt circuits, and a periodic interrupt circuit with selectable frequencies ranging from 0.5 seconds to monthly intervals. Key electrical parameters include a minimum timekeeping voltage of 0.6 V typ (0.9 V worst case) and a maximum operating voltage of 5.5 V. Timekeeping current is typically 0.18 µA at 3 V in ECO mode. The IC features built-in oscillation stabilization capacitors, high-precision frequency adjustment, and supply voltage monitoring.

Real Time Clock Feature Summary

• Ultra-low power consumption with timekeeping current as low as 0.18 µA typ at 3 V in ECO mode.
• Integrated 32.768 kHz crystal oscillator circuit with built-in load capacitors (CG and CD).
• Dual alarm interrupts: Alarm_W supports week/hour/minute settings; Alarm_D supports hour/minute settings.
• High-precision oscillation adjustment circuit allowing correction of ±1.5 ppm or ±0.5 ppm deviations.
• Supports automatic leap year identification up to 2099 and selectable 12-hour/24-hour modes.

Real Time Clock Applications

• Battery-backed systems requiring precise timekeeping with minimal standby current.
• Embedded devices needing periodic interrupts for system scheduling or data logging.
• Applications requiring supply voltage monitoring and oscillation halt detection for data integrity.
• Space-constrained designs benefiting from the compact 1.8 mm x 1.8 mm QFN package.

Real Time Clock Procurement Notes

Verify the specific ordering suffix against the manufacturer's selection guide to confirm package type and reel quantity. The R2223L-E2 designation corresponds to the QFN018018-12 package with a standard reel quantity of 3000 pieces. Ensure compatibility with the required lead frame finish and RoHS compliance status as specified in the official datasheet before finalizing procurement orders.

Real Time Clock Selection Notes

Select the R2223L-E2 when a small form factor is required, as it utilizes the QFN018018-12 package compared to the TSSOP10G option available in the R2223T series. Consider the internal register-based ECO mode implementation for this model, which differs from the pin-controlled ECO mode of the R2221x series. Verify that the external crystal load capacity matches the internal capacitor configuration for optimal frequency accuracy.

Real Time Clock Part Context

The R2223L-E2 belongs to the R2223x family of 2-wire serial interface real-time clocks. It shares core functionality with the R2221x series but distinguishes itself through its interrupt pin configuration and ECO mode activation method. While the R2221x uses an external ECO pin, the R2223x controls this mode via an internal register bit. This model is part of a broader lineup designed for low-power, high-precision timing applications in consumer and industrial electronics.

Real Time Clock Replacement Considerations

The R2221L-E2 serves as a functional alternative within the same package, though it combines both alarm outputs onto a single INTR pin rather than separating them into INTRA and INTRB. Direct pin-for-pin replacement requires verifying that the application logic can accommodate the consolidated interrupt structure of the R2221x variant.