SMJ64C16S-25JDM Legacy Hermetic 16K×8 CMOS Static RAM (SRAM) Overview
The SMJ64C16S-25JDM from Texas Instruments is a high-reliability 16K×8 static random-access memory (SRAM) engineered for ultra-high-speed legacy industrial, aerospace, and defense systems. Part of TI’s trusted portfolio of hermetic memory components, it delivers 极速、无刷新临时数据存储—ideal for applications where even nanoseconds of lag risk system failure, data corruption, or performance gaps. Its J-lead DIP (JDM-24) package, 25ns access time, and wide temperature range make it irreplaceable for maintaining older electronics that demand consistent, ultra-fast data handling in 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 SMJ64C16S-25JDM Industrial SRAM
| 参数 | 价值 | 单位 |
|---|---|---|
| 功能 | 16K×8 静态随机存取存储器 (SRAM) | |
| 内存配置 | 16,384 × 8 | 比特（128 千比特/共 16 千字节） |
| 访问时间（最长） | 25 | 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） | 85 | 毫瓦（5V 时，无负载） |
| 包装类型 | JDM-24（J 引线双列直插式封装，24 引脚，密封陶瓷） | |
| 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 SMJ64C16S-25JDM outperforms generic SRAMs, plastic-packaged alternatives, and slower memory options—starting with its unrivaled 25ns access time and hermetic durability. Unlike plastic DIPs (which degrade in 2–3 years due to moisture or corrosion), its ceramic JDM-24 enclosure and vacuum seal ensure 10+ years of reliability—critical for systems where replacement requires shutting down high-value, ultra-high-speed operations. “We replaced 40ns plastic SRAMs with this model in our 35MHz aerospace radar trackers, and target lock failures dropped from 18% to 0%,” confirms a senior engineer at a leading defense electronics firm.
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Its 25ns access time is 37.5% faster than 40ns SRAMs, eliminating micro-lag in ultra-high-speed legacy systems (30–40MHz controllers). For example, a factory precision sensor hub using a 40ns SRAM took 0.8ms to process 200 8-bit sensor data points; switching to this 25ns model cut processing time to 0.5ms. This ensured the PLC received data in time to adjust semiconductor manufacturing tools, reducing defective microchips by 40%—directly boosting yield and profitability.
As a CMOS SRAM, it uses 65% less power than TTL alternatives (85mW vs. 240mW)—a critical advantage for battery-powered test equipment or remote industrial sites (e.g., offshore oil rigs). Its power efficiency extends backup battery life by 33% during outages, preventing costly downtime for safety-critical systems like emergency shutdown controllers.
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The JDM-24’s J-lead pins also outperform standard through-hole designs: their folded shape creates 2x larger solder joints with PCBs, resisting vibration-induced failures in factory robots or aircraft. Unlike modern surface-mount SRAMs, it fits legacy JDM-24 sockets—avoiding costly PCB redesigns that would require retesting and recertifying older systems. Its -55°C to +125°C temperature range further outperforms commercial-grade SRAMs (0°C–70°C), ensuring consistent speed in freezing arctic research stations or hot desert-based radar systems.
Typical Applications of SMJ64C16S-25JDM
The SMJ64C16S-25JDM excels in legacy and mission-critical systems where ultra-speed, ruggedness, and compatibility are non-negotiable. Key use cases include:
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- Aerospace and Defense (high-speed radar target trackers, missile guidance system memory, supersonic flight telemetry buffers, weapons test data recorders)
- Industrial Automation (30–40MHz legacy PLCs, semiconductor manufacturing tool controllers, automotive high-speed assembly line sync systems, precision machine sensors)
- Test and Measurement (ultra-high-frequency oscilloscopes, dynamic strain gauges for supersonic tests, ruggedized signal generators, high-speed data acquisition tools)
- Energy and Power (oil rig high-speed monitoring controllers, wind turbine pitch control sensor memory, high-voltage substation data processors)
- 安全与监控（军用远程雷达数据缓冲器、传统高速威胁探测系统存储器）
德州仪器在密封式高速存储器领域的专长
As a Texas Instruments product, the SMJ64C16S-25JDM leverages TI’s 70+ years of leadership in industrial and military-grade semiconductors. TI’s hermetic high-speed SRAMs are engineered for both extreme performance and longevity—each unit undergoes rigorous testing to meet strict global standards: temperature cycling (-55°C to +125°C for 1,000 cycles), humidity resistance (85% RH at 85°C for 1,000 hours), and electrostatic discharge (ESD) protection (2kV human-body model, per MIL-STD-883 Method 3015).
这种对耐用性的承诺使德州仪器成为波音（航空航天）、西门子（工业自动化）和洛克希德-马丁（国防）等行业领先企业值得信赖的合作伙伴，所有这些企业都依靠德州仪器的传统内存元件来维护不易更换的关键旧系统。对于管理超高速传统基础设施的企业而言，德州仪器的元件可在不牺牲速度、效率或可靠性的情况下确保连续性。
常见问题（FAQ）
What is the SMJ64C16S-25JDM, and how does it support ultra-high-speed legacy systems?
The SMJ64C16S-25JDM is a 16K×8 hermetic CMOS SRAM designed for ultra-high-speed legacy industrial, aerospace, and defense systems. It stores temporary data without power refresh (a core SRAM advantage) and retains 16,384 independent 8-bit values. Via its CMOS-compatible parallel interface, it reads/writes data in 25ns—fast enough to sync with 30–40MHz controllers (e.g., TI 54LS TTL PLCs) and eliminate the micro-lag that disrupts ultra-high-speed operations like radar target tracking.
Why is 25ns access time critical for 30–40MHz industrial PLCs?
30–40MHz PLCs operate on 25–33 nanosecond (ns) cycles—meaning they need data delivered within this window to execute control commands. A 25ns access time matches the fastest end of this range, ensuring no delays. Slower 40ns SRAMs create a 10–15ns lag per cycle, which accumulates over 1,000 cycles to cause 10–15ms delays. These delays misalign precision tools, miscalculate sensor readings, or trigger false safety alerts—all leading to costly downtime, defective products, or safety risks.
How does the JDM-24 package improve reliability in harsh environments?
The JDM-24 is a hermetic ceramic J-lead DIP, optimized to block contaminants and resist vibration. Its ceramic enclosure is sealed with inert gas, preventing salt (coastal), dust (factories), or chemicals (oil/gas) from reaching the chip—unlike plastic DIPs that absorb these substances. Its J-lead pins also form larger solder joints with PCBs, resisting vibration that breaks standard through-hole joints. This design ensures 10+ years of use vs. 2–3 years for plastic SRAMs.
对于这种 SRAM，CMOS 技术比 TTL 技术有哪些优势？
CMOS technology delivers two critical benefits over TTL: lower power and better noise immunity. At 85mW (typical quiescent power), it uses 65% less energy than TTL SRAMs (~240mW), extending battery life in backup systems. It also has a wider noise margin (0.4V low level, 0.5V high level) vs. TTL’s 0.3V margin, making it more resistant to electrical interference from factory motors or radar—cutting data corruption errors by 48%.
Is the SMJ64C16S-25JDM compatible with mixed-signal legacy systems (TTL + CMOS)?
Yes, it works seamlessly with mixed-signal systems using TI 54LS TTL controllers and 74HC/74HCT CMOS sensors. Its CMOS input/output (I/O) levels are TTL-compatible (VIL ≤ 0.8V, VIH ≥ 2.0V), so no logic level translators are needed. It also fits existing JDM-24 sockets, letting technicians replace older SRAMs without modifying PCBs—saving time and avoiding the cost of recertifying legacy infrastructure.