R2023L-E2

Real Time Clock Overview

The R2023L-E2 is a CMOS real-time clock IC from Nisshinbo Micro Devices, utilizing a 2-wire serial interface (SCL/SDA) for CPU communication. It operates within a supply voltage range of 1.0 V to 5.5 V for timekeeping and 1.7 V to 5.5 V for access. The device features BCD-format time and calendar counters, two alarm interrupt circuits, and a periodic interrupt circuit with selectable frequencies. It includes a high-precision oscillation adjustment circuit, built-in stabilization capacitors, and a 32.768 kHz clock output. The component is housed in a QFN023023-16 package.

Real Time Clock Feature Summary

• 2-Wire Serial Interface: Supports I2C bus fast mode with a maximum SCL clock frequency of 400 kHz at VDD ≥ 1.7 V.
• Low Power Consumption: Typical timekeeping current is 0.45 µA at VDD = 3 V, with a minimum operating voltage of 0.66 V.
• Advanced Interrupts: Includes two alarm circuits (Alarm_W and Alarm_D) and a periodic interrupt circuit with five selectable frequencies ranging from 0.5 seconds to monthly.
• High-Precision Adjustment: Features an internal oscillation adjustment circuit capable of correcting frequency deviations up to ±189 ppm or ±63 ppm.

Real Time Clock Applications

• Embedded systems requiring accurate timekeeping with low power consumption.
• Devices needing periodic interrupts for background tasks or monitoring.
• Systems utilizing external microcomputers requiring a 32.768 kHz sub-clock signal.
• Applications necessitating automatic leap year identification up to the year 2099.

Real Time Clock Procurement Notes

Verify the specific package type, as the R2023x series includes TSSOP10G (R2023T), FFP12 (R2023K), and QFN023023-16 (R2023L). Confirm that the E2 suffix denotes the taping type. Note that the R2023K variant was discontinued in February 2016; ensure the selected part number matches the required physical footprint and pin configuration for the design.

Real Time Clock Selection Notes

Select the R2023L-E2 when a compact QFN023023-16 package is required. Ensure the system supply voltage meets the minimum 1.7 V requirement for reliable I2C communication if data access is frequent. Consider the oscillation adjustment capabilities if high precision is needed without external temperature compensation. Verify that the open-drain outputs for SDA, INTRA, and INTRB are compatible with the CPU's pull-up requirements.

Real Time Clock Part Context

The R2023L-E2 belongs to the R2023x family of 2-wire serial interface real-time clocks. This family offers multiple package options, including TSSOP10G and FFP12, though the FFP12 version is discontinued. The R2023L specifically utilizes the QFN023023-16 package, measuring 2.3 mm x 2.3 mm x 0.4 mm, suitable for high-density board mounting.

Real Time Clock Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation. Designers should verify compatibility with existing R2023x variants based on package dimensions and electrical characteristics.

Real Time Clock FAQ

How does the R2023L-E2 handle oscillation frequency adjustments?

It incorporates a high-precision oscillation adjustment circuit that allows correction of time count gain or loss via CPU commands. The range is approximately ±189 ppm or ±63 ppm in increments of approximately 3 ppm or 1 ppm, depending on the DEV bit setting.

What are the differences between Alarm_W and Alarm_D?

Alarm_W supports week, hour, and minute settings, allowing combinations like specific days of the week. Alarm_D supports only hour and minute settings. Alarm_W interrupts are output via the INTRB pin, while Alarm_D interrupts are output via the INTRA pin.

Can the 32.768 kHz clock output be disabled?

Yes, the 32KOUT pin can be disabled by setting both CLEN1 and CLEN2 bits to 1 or by holding the CLKC pin low. Disabling requires manipulation of two registers with different addresses to prevent accidental shutdown due to CPU runaway.