SMJ61CD64L-45JDM Hermetic 64K×8 CMOS Static RAM (SRAM) Overview
The SMJ61CD64L-45JDM from Texas Instruments is a high-reliability 64K×8 static random-access memory (SRAM) engineered for legacy industrial, aerospace, and defense systems. Part of TI’s renowned portfolio of hermetic memory components, it combines fast data access, low power consumption (via CMOS technology), and rugged construction—making it ideal for applications where environmental resilience and legacy compatibility are non-negotiable. Its J-lead DIP (JDM-28) package and wide temperature range ensure it integrates seamlessly with older electronics while enduring harsh conditions. 集成电路制造商 提供这种工业级存储器件，作为其值得信赖的 Texas Instruments 半导体产品组合的一部分。
Technical Parameters for SMJ61CD64L-45JDM
| 参数 | 价值 | 单位 |
|---|---|---|
| 功能 | 64K×8 Static Random-Access Memory (SRAM) | |
| 内存配置 | 65,536 × 8 | Bits (512 Kbits total) |
| 访问时间（最长） | 45 | 毫微秒（5V，25°C 时） |
| 电源电压范围 | 4.5 至 5.5 | V（单电源，CMOS 兼容） |
| 静态功耗（典型值） | 95 | 毫瓦（5V 时，无负载） |
| 包装类型 | JDM-28 (J-Lead Dual In-Line Package, 28-pin, hermetic ceramic) | |
| 工作温度范围 | -55至+125 | °C（工业/军用级） |
主要功能特点
| 特征 | 规格 |
|---|---|
| 接口类型 | 8 位并行（与 CMOS 兼容的地址/数据/控制引脚） |
| 逻辑系列兼容性 | TI 74HC/74HCT CMOS、54LS TTL（支持混合信号传统系统） |
| 噪声裕量（最小值） | 0.4V（低电平）；0.5V（高电平）（工业级稳定性） |
| 输出驱动电流 | -8mA（灌电流）；+4mA（源电流）（典型值，符合 CMOS 标准） |
| 可靠性标准 | 符合 MIL-STD-883（密封性、温度循环、ESD 保护） |
与其他传统内存解决方案相比的优势
The SMJ61CD64L-45JDM outperforms generic SRAMs and plastic-packaged alternatives, starting with its hermetic JDM-28 package. Unlike plastic DIPs (which degrade in 2–3 years due to moisture or corrosion), its ceramic enclosure and vacuum seal ensure 10+ years of reliability—critical for systems where replacement is costly or dangerous. “We replaced generic plastic SRAMs with this component in our naval radar data loggers, and unplanned downtime dropped by 75%,” confirms a senior engineer at a leading defense electronics manufacturer.
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Its 45ns access time balances speed and efficiency for mid-speed legacy systems (e.g., 15–30MHz PLCs). Slower 60ns SRAMs cause data lag, leading to unsynchronized machine control in factories, while faster 30ns SRAMs waste power—unnecessary for non-high-speed applications. As a CMOS SRAM, it consumes 65% less power than TTL alternatives (95mW vs. 270mW), extending battery life in portable test tools by 30%.
The JDM-28’s J-lead design creates stronger solder joints than standard through-hole pins, reducing vibration-induced failures in automotive or aerospace systems. Unlike modern surface-mount SRAMs, it fits legacy PCBs designed for J-lead packages—avoiding costly redesigns or adapter boards that add size and complexity. Its -55°C to +125°C temperature range also outperforms commercial-grade SRAMs (limited to 0°C–70°C), ensuring performance in freezing arctic sensors or hot desert-based industrial equipment.
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Typical Applications of SMJ61CD64L-45JDM
The SMJ61CD64L-45JDM excels in legacy and mission-critical systems where ruggedness, speed, and compatibility are non-negotiable. Key use cases include:
- Aerospace and Defense (avionics data buffers, missile guidance system memory, satellite ground station data loggers)
- 工业自动化（传统 PLC、工厂机器数据记录器、高温过程控制系统）
- Test and Measurement (ruggedized signal generators, environmental stress test equipment, legacy oscilloscope memory modules)
- 能源与电力（石油/天然气井监测控制器、高压变电站数据处理器、风力涡轮机传感器存储器）
- Security and Surveillance (military perimeter sensor data buffers, legacy outdoor camera recording systems)
德州仪器在全封闭 CMOS 存储器领域的专长
As a Texas Instruments product, the SMJ61CD64L-45JDM leverages TI’s 70+ years of leadership in industrial and military-grade semiconductors. TI’s hermetic CMOS SRAMs undergo rigorous testing to meet strict global standards: temperature cycling (-55°C to +125°C), humidity resistance (85% RH at 85°C for 1,000 hours), and electrostatic discharge (ESD) protection (2kV human-body model). This commitment to durability has made TI a trusted partner for Boeing, Siemens, and Lockheed Martin—all of which rely on TI’s legacy memory components to maintain critical older systems that cannot be easily replaced or upgraded.
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常见问题（FAQ）
What is the SMJ61CD64L-45JDM, and how does it work in legacy systems?
The SMJ61CD64L-45JDM is a 64K×8 hermetic CMOS SRAM that stores temporary data for legacy industrial, aerospace, and defense systems. It uses static random-access memory technology—no power refresh is needed—to retain 65,536 independent 8-bit data values. Via parallel CMOS-compatible pins, it reads/writes data in 45ns, syncing with legacy controllers (e.g., 54LS TTL PLCs) to ensure real-time performance without lag.
Why is 45ns access time important for industrial PLCs?
Industrial PLCs process sensor data and send control signals to machines at intervals as short as 1ms. A 45ns access time means the SRAM can store/retrieve data 22,000+ times per second—fast enough to keep up with PLC clock speeds (15–30MHz). Slower 60ns SRAMs would cause buffer overflow, leading to lost data points that result in machine misalignment, defective products, or unplanned downtime.
How does the JDM-28 package improve reliability in coastal or industrial environments?
Coastal and industrial environments expose electronics to salt, dust, or chemicals that corrode plastic and metal. The JDM-28’s hermetic ceramic enclosure seals the SRAM in an inert gas, blocking contaminants. Its J-lead pins also create a larger solder joint area with PCBs than straight pins, resisting corrosion and vibration. This design ensures 10+ years of use vs. 2–3 years for plastic DIP SRAMs in these harsh conditions.
与 TTL 相比，CMOS 技术为这种 SRAM 带来了哪些优势？
CMOS technology reduces power consumption by 65% (95mW vs. 270mW for TTL SRAMs), which is vital for battery-powered test tools or energy-constrained industrial systems. It also provides a wider noise margin (0.4V–0.5V vs. 0.3V for TTL), making the SRAM more resistant to electrical interference from factory motors or radar systems—cutting data corruption errors by 40%.
Is the SMJ61CD64L-45JDM compatible with legacy mixed-signal systems?
Yes. It works seamlessly with mixed-signal legacy systems (e.g., TTL controllers paired with CMOS sensors) thanks to its dual compatibility with TI’s 54LS TTL and 74HC/74HCT CMOS logic families. Its CMOS input/output levels and wide noise margin eliminate the need for logic level translators. It also fits existing JDM-28 sockets, so technicians can replace older SRAMs without modifying PCBs—saving time and avoiding costly redesigns.