DS1338U-3+ - Low-Power I2C RTC with 56B NV RAM | Analog Devices
部品番号: DS1338U-3+ ✓ 生産中DS1338U-3+ 概要
A real-time clock is a clock-and-timing IC that maintains time independently of the system processor and can preserve calendar or configuration data across power interruptions. The DS1338U-3+ combines an RTC timebase with 56 bytes of NV SRAM, making it useful for embedded systems that need both timestamping and small quantities of retained data. Its low-power design suits battery-backed equipment where continued timekeeping is required while the main supply is absent.
The verified manufacturer description identifies the DS1338 series as a full BCD clock/calendar with serial I2C access. The clock/calendar information includes seconds, minutes, hours, day, date, month, and year, while the end-of-month date is automatically adjusted for shorter months. The -3+ ordering suffix is associated with the 2.7 V device variant in the distributor data; exact electrical limits not present in the supplied source snippets are marked as data needed rather than inferred.
Typical uses include industrial controllers, data loggers, meters, embedded instruments, and battery-powered systems that require an independent time reference. The I2C interface allows the host processor to read or write clock registers and access the NV SRAM without dedicating multiple parallel pins. Designers should preserve the device-specific pinout and verify voltage, current, oscillator, accuracy, and retention specifications against the manufacturer datasheet before releasing a production design.
A key design consideration is matching the RTC supply architecture to the system power source. If the device is intended to maintain time during a main-power interruption, the backup supply and current-consumption requirements must be designed together with the load switch and battery path. The host firmware should also account for I2C address configuration and calendar rollover behavior.
This page combines verified distributor and manufacturer information, structured specifications, application guidance, design notes, and only the drop-in alternatives supported by the supplied cross-reference data. It is intended to help engineers evaluate the DS1338U-3+ for embedded timing and nonvolatile data-retention designs while avoiding unsupported assumptions.
ドロップイン代替品: DS1338U-3+ — 同一パッケージでピン互換。PCBの作り直しが必要な異なるパッケージの部品は除外されています。
このシリーズのバリエーション
同一シリーズでドロップイン互換のモデル: DS1338U-3+ （同一形状・フットプリント） — 相違点: Package, Package Width, RoHS Status.
DS1338U-3
✅ ドロップイン📋 参考代替品（カタログ未掲載）
DS1338U-33+
✅ ドロップイン📋 参考代替品（カタログ未掲載）
DS1308U-3+
✅ ドロップイン📋 参考代替品（カタログ未掲載）
DS1338C-3#
✅ ドロップイン価格はお問い合わせください
データシートを見る →DS1340U-33+
✅ ドロップイン📋 参考代替品（カタログ未掲載）
DS1338U-3+ 仕様
| Product Type | Serial real-time clock (RTC) with clock/calendar and NV SRAM |
| Manufacturer | Analog Devices Inc./Maxim Integrated |
| インターフェース | I2C serial interface |
| Calendar Encoding | Full BCD |
| Calendar Fields | Seconds, minutes, hours, day, date, month, year |
| End-of-Month Adjustment | Automatic adjustment for months with fewer than 31 days |
| Nonvolatile SRAM | 56 bytes |
| パッケージ | 8-pin µMAX/TSSOP-style package |
| Terminal Count | 8 terminals |
| Package Width | 3.00 mm |
| Package Length | 0.118 in |
| Terminal Form | Gull wing |
| Temperature Grade | Industrial |
| RoHS ステータス | unknown |
| REACH Status | unknown |
| AEC-Q100 Qualification | not_applicable |
| Lead-Free Status | unknown |
| Halogen-Free Status | unknown |
DS1338U-3+ 0.118 in ピン配置ガイド
DS1338U-3+ (0.118 in パッケージ) のピン配置。 ピン番号、機能、接続図はメーカーのデータシートで定義されています。正確なフットプリントとはんだ付けのガイドラインについては、データシートを参照してください。
詳細なピン配置データはありません: DS1338U-3+.
詳細は データシート をご参照ください。
主な用途
DS1338U-3+ の用途: 7 件s: Battery-Backed Industrial Data Logger, Embedded Measurement Instrument, Battery-Powered Sensor Node, Embedded Controller Timebase, Data Acquisition and Event Ordering, Compact Access-Control and Security Controller, Portable Medical or Diagnostic Equipment.
Battery-Backed Industrial Data Logger
The DS1338U-3+ fits a battery-backed data logger because it combines a dedicated BCD clock/calendar with 56 bytes of NV SRAM. The host controller can timestamp records through the I2C interface and retain a small configuration block across a power interruption. This is useful when the main supply is absent but the product still needs event ordering. The exact backup current, retention duration, and operating voltage must be taken from the manufacturer datasheet before sizing the battery and load switch.
おすすめ
Embedded Measurement Instrument
The DS1338U-3+ can provide time stamps for meters, test equipment, and compact measurement instruments. Its seconds-through-year calendar fields support event ordering, while the 56-byte NV SRAM can retain a small calibration identifier, instrument counter, or operating mode setting. The RTC keeps time independently of the main controller, allowing the system to present a valid timestamp even after a reset. Verify the exact I2C address and register access sequence in the manufacturer documentation.
おすすめ
Battery-Powered Sensor Node
The DS1338U-3+ is a useful timing companion for a low-power sensor node that must preserve event order during intermittent operation. The 56-byte NV area can hold a small status record, while the BCD calendar provides human-readable time fields to the host processor. The device does not eliminate the need for low-power firmware: the controller should wake periodically, read the RTC, and return to sleep. Supply current and oscillator accuracy are not present in the supplied sources and must be verified before battery-life estimation.
おすすめ
Embedded Controller Timebase
The DS1338U-3+ gives an embedded controller a dedicated, low-power calendar source instead of relying on software timing tied to the processor. The host reads seconds, minutes, hours, date, month, and year over I2C, while the RTC’s automatic shorter-month handling reduces calendar logic. This arrangement is useful in controllers that sleep between tasks but must preserve a consistent time base. The final firmware should handle rollover and invalid-clock conditions according to the manufacturer register definitions.
おすすめ
Data Acquisition and Event Ordering
The DS1338U-3+ can annotate acquisition records with calendar time while the 56-byte NV SRAM stores limited persistent context. In a data-acquisition product, this helps distinguish events that occur after a controller reset or power cycle. The two-wire interface conserves package pins and is suitable for sharing with other I2C peripherals, although the complete bus loading and pull-up design must follow the selected system topology. Confirm the package footprint and pin numbering before placing the device beside the controller.
おすすめ
Compact Access-Control and Security Controller
The DS1338U-3+ can support timestamped access events in a compact access-control or security controller. Its clock/calendar gives the host an independent event time, and the small NV SRAM can retain a limited device counter or configuration record. This use case is attractive when the controller must retain time through a short power interruption without dedicating a separate nonvolatile storage device for small amounts of data. Do not use the 56-byte SRAM as the sole security credential store; protect access to the I2C bus and validate the system’s tamper-resistance requirements.
おすすめ
Portable Medical or Diagnostic Equipment
The DS1338U-3+ can provide persistent timestamps for portable diagnostic equipment that records events or device sessions. The RTC separates timekeeping from the main processor, while the 56-byte NV SRAM can hold a limited operating counter or configuration marker. Because the supplied data does not provide medical qualification, battery current, or reliability figures, this application requires a separate system-level compliance review. Confirm electrical limits and the exact package before using the part in a regulated design.
おすすめ
おすすめ製品の概要
エンジニアリング参考データ: DS1338U-3+ — 比較、設計ガイダンス、コンプライアンス情報。
選定ガイド
代替品との比較
| パラメータ | この製品 | DS1338U-3 | DS1338U-33+ | DS1308U-3+ | DS1338C-3# | DS1340U-33+ |
|---|---|---|---|---|---|---|
| Function | I2C real-time clock/calendar with 56 bytes NV SRAM | Related DS1338U RTC; exact suffix differences require verification | Related DS1338U RTC; exact suffix differences require verification | Related low-current I2C RTC with 56-byte memory description | DS1338 family comparison candidate | Related RTC candidate; exact equivalence unverified |
主な差別化要因
- Integrated calendar and persistent small data store （vs DS1308U-3+)
- Calendar month-length handling （vs DS1338U-33+)
- Two-wire serialized access （vs DS1338C-3#)
設計ノート
Design the DS1338U-3+ supply and backup path together with the system load switch. The verified sources identify the part as a low-power RTC but do not provide supply current, standby current, or backup-source limits. Confirm those values in the manufacturer datasheet, then verify that pull-ups and other connected peripherals do not defeat the intended low-power state. Use the exact recommended capacitor and backup-battery configuration rather than deriving a battery budget from the RTC function alone.
Place the DS1338U-3+ close to the controller and route the I2C signals as a compact two-wire bus. Keep the package footprint and pin numbering aligned with the official 8-pin package drawing; the supplied snippets do not provide the complete pin map. Check pull-up placement so the bus remains usable during low-power states and does not create excessive leakage from the RTC supply. Confirm the selected package variant before releasing the PCB footprint.
Do not treat a related DS1338U or DS1340U ordering suffix as proof of interchangeability. Before replacing DS1338U-3+, compare supply range, I2C address, clock-register map, NV SRAM behavior, package markings, temperature grade, and oscillator requirements. The supplied search results identify several comparison candidates but do not provide a complete manufacturer cross-reference. A successful prototype should not be treated as production equivalence without this full verification.
Keep the RTC timebase and its required support components away from noisy switching nodes, high-current return paths, and sources of strong electromagnetic coupling. Follow the manufacturer reference circuit for the timebase and decoupling, because the supplied data does not specify the oscillator topology or required loading. Provide a stable ground reference and avoid routing sensitive I2C traces parallel to long power-switching edges. Validate signal integrity with the final bus topology and load conditions.
Treat the DS1338U-3+ I2C bus as a shared two-wire resource. Account for pull-up voltage, bus capacitance, speed, peripheral address conflicts, and the controller’s sleep or reset state. The verified sources identify I2C address and data transfer but do not provide the address or timing values; obtain those from the manufacturer documentation. Add bus-contention or brownout testing when the RTC must remain available during power transitions.
コンプライアンス情報
The supplied manufacturer and distributor snippets do not state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-mineral status. These fields remain unknown rather than inferred.
