SMJ68CE16S-70JDM Legacy Hermetic 128K×8 CMOS Static RAM (SRAM) Overview
The SMJ68CE16S-70JDM from Texas Instruments is a high-reliability 128K×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 delivers non-volatile temporary data storage (no power refresh required) and excels in applications where environmental resilience, legacy compatibility, and balanced speed/power efficiency are critical. Its J-lead DIP (JDM-32) package, 70ns access time, and wide temperature range make it a staple for maintaining older electronics that demand consistent performance in harsh conditions. Fabricante de CI ofrece este componente de memoria de calidad industrial como parte de su cartera de semiconductores de confianza de Texas Instruments.
Technical Parameters for SMJ68CE16S-70JDM Industrial SRAM
| Parámetro | Valor | Unidad |
|---|---|---|
| Función | Memoria estática de acceso aleatorio (SRAM) 128K×8 | |
| Configuración de la memoria | 131,072 × 8 | Bits (1024 Kbits / 128 Kbytes en total) |
| Tiempo de acceso (máx.) | 70 | ns (a 5V, 25°C) |
| Rango de tensión de alimentación | 4,5 a 5,5 | V (alimentación única, compatible con CMOS) |
| Disipación de potencia en reposo (típica) | 80 | mW (a 5 V, sin carga) |
| Tipo de envase | JDM-32 (J-Lead Dual In-Line Package, 32 patillas, cerámica hermética) | |
| Temperatura de funcionamiento | -55 a +125 | °C (grado industrial/militar) |
Características funcionales clave
| Característica | Especificación |
|---|---|
| Tipo de interfaz | 8 bits en paralelo (pines de dirección/datos/control compatibles con CMOS) |
| Compatibilidad de familias lógicas | TI 74HC/74HCT CMOS, 54LS TTL (compatibilidad con sistemas heredados de señal mixta) |
| Margen de ruido (mín.) | 0,4 V (nivel bajo); 0,5 V (nivel alto) (estabilidad industrial) |
| Corriente de salida | -8mA (sink); +4mA (source) (típico, CMOS-compliant) |
| Normas de fiabilidad | Conforme a MIL-STD-883 (hermeticidad, ciclos de temperatura, protección ESD) |
Ventajas sobre otras soluciones de memoria heredada
The SMJ68CE16S-70JDM outperforms generic SRAMs, plastic-packaged alternatives, and even faster but less efficient memory options, starting with its hermetic JDM-32 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 plastic SRAMs with this model in our offshore wind turbine sensors, and memory failures dropped from 15% to 0% annually,” confirms a senior engineer at a leading renewable energy firm.
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Its 70ns access time strikes a perfect balance for mid-speed legacy systems (e.g., 8–15MHz PLCs). Faster 40–50ns SRAMs waste power (consuming 30% more energy) for minimal speed gains, while slower 90ns SRAMs cause data lag that disrupts sensor-to-controller sync. As a CMOS SRAM, it uses 65% less power than TTL alternatives (80mW vs. 225mW), extending backup battery life in industrial systems by 20% during power outages—a critical benefit for safety-critical equipment.
The JDM-32’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 sensor stations or hot desert-based industrial equipment.
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Typical Applications of SMJ68CE16S-70JDM
The SMJ68CE16S-70JDM excels in legacy and mission-critical systems where ruggedness, balanced speed/power, and compatibility are non-negotiable. Key use cases include:
- Aeroespacial y defensa (búferes de datos de aviónica, memoria de sistemas de guiado de misiles, registradores de estaciones terrestres de satélites)
- Industrial Automation (legacy PLCs, factory machine data loggers, high-temperature process control systems)
- Energía y potencia (controladores de monitorización de pozos de petróleo/gas, memoria de sensores de aerogeneradores, procesadores de datos de subestaciones de alta tensión)
- Pruebas y mediciones (generadores de señales reforzados, equipos de pruebas de estrés ambiental, memoria de osciloscopios heredada)
- Seguridad y vigilancia (búferes de datos de sensores perimetrales militares, módulos de grabación de cámaras exteriores heredadas)
Experiencia de Texas Instruments en memorias CMOS herméticas
As a Texas Instruments product, the SMJ68CE16S-70JDM 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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Preguntas más frecuentes (FAQ)
What is the SMJ68CE16S-70JDM, and how does it work in legacy systems?
The SMJ68CE16S-70JDM is a 128K×8 hermetic CMOS SRAM that stores temporary data for legacy industrial, aerospace, and defense systems. It uses static memory technology—no power refresh is needed—to retain 131,072 independent 8-bit data values. Via parallel CMOS-compatible pins, it reads/writes data in 70ns, syncing with legacy controllers (e.g., 54LS TTL PLCs) to ensure real-time performance without unnecessary power drain.
Why is 70ns access time a good balance for mid-speed industrial PLCs?
Mid-speed PLCs (8–15MHz) process data at intervals of 67–125ns per cycle—fast enough for most factory tasks but not requiring ultra-fast memory. A 70ns access time matches these cycle times perfectly: it’s fast enough to avoid data lag, but not so fast that it wastes power (unlike 40ns SRAMs, which consume 30% more energy). This balance cuts operational costs and extends battery life in backup-powered systems.
How does the JDM-32 package improve reliability in vibration-prone environments?
Vibration-prone environments (e.g., wind turbines, factory robots) often damage standard through-hole SRAM solder joints. The JDM-32’s J-lead pins fold under the package, creating a larger solder joint area with the PCB that absorbs vibration. In testing, J-lead joints lasted 5x longer than standard straight pins in high-vibration conditions, reducing unplanned downtime for critical equipment.
¿Qué ventajas ofrece la tecnología CMOS para esta SRAM en comparación con la TTL?
CMOS technology reduces power consumption by 65% (80mW vs. 225mW for TTL SRAMs), which is vital for battery-powered test tools or industrial systems with backup power. 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 35%.
Is the SMJ68CE16S-70JDM 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-32 sockets, so technicians can replace older SRAMs without modifying PCBs—saving time and avoiding costly redesigns.