DS1338U-3+T&R - 3.3V I2C RTC with 56B NV SRAM | Maxim
料号： DS1338U-3+T&R ✓ 量产中DS1338U-3+T&R 概述
A real-time clock is a semiconductor timer that continues tracking time independently of the system processor. The DS1338U belongs to the RTC and clock/calendar hierarchy, where the clock oscillator and calendar logic preserve time while the host controller reads and writes registers through a serial bus. Its I2C interface reduces the number of signal connections needed compared with a parallel real-time clock, making it suitable for compact embedded systems, industrial controllers, and data-acquisition equipment.
The verified device information identifies an 8-pin package with gull-wing leads, an I2C two-wire serial interface, 56 bytes of NV RAM, and a 2.7 V to 3.3 V supply range. The DS1338U-3+T&R ordering code denotes the 3.3 V version supplied in tape-and-reel packaging. The manufacturer describes the device as low power and provides full BCD clock/calendar information. Additional operating limits, oscillator accuracy, current consumption, and electrical timing values are not included in the supplied verified records and therefore remain marked as data needed rather than being estimated.
The DS1338 architecture separates timekeeping from the host processor, allowing the controller to retrieve calendar data without maintaining a software time counter. The 56-byte NV RAM can retain a limited amount of configuration or operational information across power cycles. Because the device uses I2C, its bus pull-up requirements, address configuration, operating voltage, and backup-power behavior must be checked against the complete manufacturer datasheet before layout signoff or firmware deployment.
Typical uses include industrial automation controllers, embedded instrumentation, metering equipment, communications systems, and compact control boards that need date and time records. In a metering application, the RTC can establish event timestamps while NV RAM stores configuration fragments. In industrial control, it can preserve a time reference independently of the main controller. In communications equipment, the calendar can support event logging and protocol timestamping when the host does not maintain reliable wall-clock time.
The primary design consideration is to verify the complete electrical and pinout data before PCB release. The supplied records identify the package and interface but do not provide a verified pin-by-pin description, oscillator load-capacitor recommendations, or backup-supply requirements. Designers should therefore confirm those details in the current Analog Devices DS1338 or DS1338U datasheet rather than infer them from the distributor summaries.
This page consolidates the verified manufacturer description, distributor package and supply information, and drop-in comparison evidence for the DS1338U family. It also distinguishes directly verified attributes from unavailable parameters, helping engineers identify the correct voltage variant and determine whether a same-package family member can replace the target without unnecessary redesign.
直接替换替代料： DS1338U-3+T&R ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： DS1338U-3+T&R （相同外形与封装尺寸） ——差异在于 Package Type, Product Type, Serial Interface, Terminal Count, Time Format.
DS1338U-18+T&R
✅ 直接替换联系询价
查看数据手册 →DS1338U-33+T&R
✅ 直接替换📋 参考替代料（不在目录中）
DS1338U-3+T&R 规格参数
| Product Type | Serial real-time clock and calendar with NV SRAM |
| Supply Voltage Range | 2.7 V to 3.3 V |
| Nominal Supply Voltage | 3.3 V |
| Clock and Calendar Format | Full binary-coded decimal (BCD) |
| Calendar Information | Seconds, minutes, hours, day, date, month, and year |
| Serial Interface | I2C, 2-wire serial |
| NV SRAM Capacity | 56 bytes |
| 封装 | 8-TSSOP |
| Package Type | 8-MSOP (0.118 inch, 3.00 mm width) |
| Terminal Count | 8 terminals |
| Terminal Form | Gull wing |
| Temperature Grade | Industrial |
| Date Format | YY-MM-DD-dd |
| Time Format | HH:MM:SS, 12/24-hour |
| Orderable Packaging | Tape and reel |
DS1338U-3+T&R 8-msop (0.118 inch, 3.00 mm width) 引脚配置指南
DS1338U-3+T&R（8-msop (0.118 inch, 3.00 mm width) 封装）的引脚配置。 引脚编号、功能和连接图在制造商数据手册中定义。请参阅该手册以了解确切的封装尺寸和焊接指南。
暂无详细引脚数据： DS1338U-3+T&R.
请参阅 数据手册 以查看完整引脚配置。
典型应用
DS1338U-3+T&R 适用于 6 应用s: Industrial Automation Controllers, Energy Metering and Data Loggers, Embedded Data-Acquisition Equipment, Communications and Network Equipment, Portable and Battery-Powered Instruments, Test and Measurement Equipment.
Industrial Automation Controllers
The DS1338U-3+T&R fits industrial automation controllers that need an independent calendar reference and a small amount of persistent configuration storage. Its 3.3 V operating option aligns with 2.7 V to 3.3 V compatible control electronics, while the I2C interface reduces connection count compared with a parallel real-time clock. The 56-byte NV RAM can retain limited operating parameters or counter data across resets, subject to the verified retention and backup conditions in the manufacturer datasheet. Because the supplied listing identifies an industrial temperature grade, the device is a strong starting point for factory equipment, but the complete operating-temperature and electrical limits must be checked before qualification.
推荐
Energy Metering and Data Loggers
The DS1338U-3+T&R is suitable for energy-metering and data-logging equipment that must associate readings with calendar time. Its clock/calendar supplies seconds through year information in BCD form, and the I2C interface allows a host controller to read or update time efficiently over a shared bus. The 56-byte NV RAM offers a compact place for configuration fragments or event-related values, although retention duration remains dependent on the exact backup-power implementation. For revenue-sensitive or regulatory measurement systems, engineers should confirm oscillator accuracy, calibration provisions, power-loss behavior, and data-retention specifications in the current Analog Devices documentation.
推荐
Embedded Data-Acquisition Equipment
The DS1338U-3+T&R fits compact data-acquisition systems that need accurate timestamps for sampled measurements. The processor can query the clock/calendar through the two-wire I2C interface and use the calendar fields to label events, while the 56-byte NV RAM can preserve a small amount of configuration or a synchronization marker. Its 8-TSSOP format helps conserve board area compared with larger parallel-interface RTC packages. For precision measurements, the RTC should not be assumed to replace a high-accuracy disciplined clock; designers should evaluate the documented oscillator tolerance, calibration approach, and long-term drift for the required measurement class.
推荐
Communications and Network Equipment
The DS1338U-3+T&R can support communications equipment that records message, alarm, or maintenance events against a local calendar. Its I2C interface is compatible with the serial buses commonly used by embedded communications controllers, and the clock/calendar automatically accounts for months containing fewer than 31 days according to the manufacturer description. The NV RAM can hold limited counters or configuration values, but it should not be treated as a large event log. Network-facing designs should also evaluate oscillator drift, initial time-setting procedures, leap-year handling, and behavior during extended power loss using the complete manufacturer datasheet.
推荐
Portable and Battery-Powered Instruments
The DS1338U-3+T&R is applicable to portable instruments where calendar information and limited persistent state must be retained without relying entirely on the host controller. Its I2C interface allows the device to coexist with other bus peripherals, and the 8-TSSOP package supports space-constrained layouts. The manufacturer describes the DS1338 family as low power, but the supplied records do not quantify active, idle, or backup current. Before selecting it for a battery-powered product, engineers should calculate the average current using the manufacturer operating-current data, verify the backup path, and determine whether the 56 bytes of NV RAM meet the required retention and write-cycle expectations.
推荐
Test and Measurement Equipment
The DS1338U-3+T&R is appropriate for test and measurement equipment that timestamps setup changes, calibration records, or diagnostic events. The real-time clock provides calendar information independently of the main processor, while the I2C interface enables straightforward firmware access to time and the 56-byte NV memory. This arrangement is useful where instrument data must remain organized by date even if the primary controller restarts. However, laboratory applications may impose stricter requirements for oscillator stability, calibration accuracy, and retention time than the verified records establish. Use the official DS1338 and DS1338U datasheets to verify those characteristics and the exact oscillator load-capacitor network.
推荐
推荐产品汇总
工程参考数据： DS1338U-3+T&R ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | DS1338U-18+T&R | DS1338U-33+T&R |
|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Analog Devices / Maxim Integrated |
| Package | 8-TSSOP / 8-MSOP, 3.00 mm width | 8-pin µSOP - same family package | 8-TSSOP / 8-MSOP, 3.00 mm width |
| Nominal Voltage Option | 3.3 V - -3 suffix | -18 suffix | 3.3 V - -33 suffix |
| Interface | I2C, 2-wire serial | I2C | I2C, 2-wire serial |
| NV SRAM Capacity | 56 bytes | 56 bytes | 56 bytes |
| Calendar Representation | Full BCD clock/calendar | Full BCD clock/calendar | Full BCD clock/calendar |
关键差异点
- Direct 3.3 V orderable configuration （对比 DS1338U-18+T&R)
- Clock and NV memory in one device （对比 DS1338U-33+T&R)
- Compact two-wire integration （对比 DS1338U-18+T&R)
设计说明
Place the DS1338U-3+T&R close to the controller that owns its I2C bus and route SDA and SCL away from high-current switching nodes. The supplied verified data confirms an I2C interface but does not provide the recommended pull-up values or maximum bus capacitance. Determine those values from the current manufacturer datasheet, then verify that the bus capacitance, pull-up resistance, rise time, and logic levels remain valid at 2.7 V, which is the lowest stated operating voltage.
Do not treat every DS1338U suffix as electrically interchangeable merely because the package is the same. The target uses the -3 orderable suffix, while the verified comparison candidates include DS1338U-18+T&R and DS1338U-33+T&R. Confirm the manufacturer suffix definitions, supply limits, oscillator configuration, and backup behavior before substitution. A same-package part can still be unsuitable if its operating voltage does not match the system rail.
The complete verified package and pin mapping is not included in the supplied records, so the oscillator and backup connections must be laid out only after checking the current Analog Devices DS1338 or DS1338U datasheet. Pay particular attention to the crystal or oscillator connection, ground return, supply decoupling, and any backup-supply routing. Avoid long traces between the RTC oscillator circuitry and the device, and follow the manufacturer grounding and layout guidance for the final package.
Budget the RTC supply and any backup source independently from the main load. The verified manufacturer information identifies a 2.7 V to 3.3 V range and describes the family as low power, but active current, standby current, leakage, and backup-cell consumption are not included. Use the current datasheet values to calculate battery-life impact, especially for instruments or meters that remain unpowered for long periods while expecting retained calendar data and NV SRAM contents.
合规信息
The supplied verified records do not explicitly state RoHS, REACH, lead-free, halogen-free, or conflict-minerals status. AEC-Q100 is not applicable because this is an industrial real-time clock rather than an explicitly automotive-qualified device.
