SMJ68CE16L-45JDM Legacy Hermetic 128K×8 CMOS Static RAM (SRAM) Overview
The SMJ68CE16L-45JDM from Texas Instruments is a high-reliability 128K×8 static random-access memory (SRAM) engineered for high-speed legacy industrial, aerospace, and defense systems. Part of TI’s trusted portfolio of hermetic memory components, it delivers ultra-fast, non-refresh temporary data storage—ideal for applications where speed, environmental resilience, and legacy compatibility are non-negotiable. Its J-lead DIP (JDM-32) package, 45ns access time, and wide temperature range make it a staple for maintaining older electronics that demand consistent, high-performance data handling 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 SMJ68CE16L-45JDM 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.) | 45 | 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) | 88 | 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 SMJ68CE16L-45JDM outperforms generic SRAMs, plastic-packaged alternatives, and slower 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 60ns plastic SRAMs with this model in our 22MHz aerospace radar systems, and target tracking errors dropped by 32%,” confirms a senior engineer at a leading defense electronics firm.
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Its 45ns access time is 25% faster than 60ns SRAMs, eliminating micro-lag in high-speed legacy systems (20–25MHz controllers). For example, a factory sensor hub using a 60ns SRAM took 1.2ms to process 250 8-bit sensor data points; switching to this 45ns model cut processing time to 0.9ms. This ensured the PLC received data in time to adjust motor speeds, reducing defective parts by 33% in high-speed assembly lines—directly boosting throughput and lowering waste.
As a CMOS SRAM, it uses 62% less power than TTL alternatives (88mW vs. 230mW), extending backup battery life in industrial systems by 29% during power outages. This is a critical benefit for safety-critical equipment like emergency shutdown controllers, especially in remote sites (e.g., offshore wind farms) where backup power is limited.
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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 failure risks. Its -55°C to +125°C temperature range also outperforms commercial-grade SRAMs (0°C–70°C), ensuring performance in freezing arctic sensors, hot engine bays, or coastal radar systems.
Typical Applications of SMJ68CE16L-45JDM
The SMJ68CE16L-45JDM excels in legacy and mission-critical systems where ultra-fast speed, ruggedness, and compatibility are non-negotiable. Key use cases include:
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- Aerospace and Defense (avionics telemetry buffers, missile guidance system memory, radar target tracking loggers, high-speed flight test data recorders)
- Industrial Automation (20–25MHz legacy PLCs, factory high-speed sensor hubs, precision machine tool controllers, automotive assembly line sync systems)
- Test and Measurement (high-frequency oscilloscopes, dynamic strain gauges, ruggedized signal generators, environmental stress test equipment)
- Energy and Power (oil/gas well high-speed monitoring controllers, wind turbine pitch control sensor memory, high-voltage substation data processors)
- Security and Surveillance (military perimeter radar data buffers, legacy high-speed camera recording modules, threat detection system memory)
Experiencia de Texas Instruments en memorias CMOS herméticas
As a Texas Instruments product, the SMJ68CE16L-45JDM leverages TI’s 70+ years of leadership in industrial and military-grade semiconductors. TI’s hermetic CMOS SRAMs are engineered for both 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).
This commitment to durability has made TI a trusted partner for industry leaders like Boeing (aerospace), Siemens (industrial automation), and Lockheed Martin (defense)—all of which rely on TI’s legacy memory components to maintain critical older systems that cannot be easily replaced. For businesses managing high-speed legacy infrastructure, TI’s components ensure continuity without sacrificing speed, efficiency, or reliability.
Preguntas más frecuentes (FAQ)
What is the SMJ68CE16L-45JDM, and how does it support high-speed legacy systems?
The SMJ68CE16L-45JDM is a 128K×8 hermetic CMOS SRAM designed for high-speed legacy industrial, aerospace, and defense systems. It stores temporary data without power refresh (a core SRAM benefit) and retains 131,072 independent 8-bit values. Via its CMOS-compatible parallel interface, it reads/writes data in 45ns—fast enough to sync with 20–25MHz controllers (e.g., TI 54LS TTL PLCs) and eliminate micro-lag that disrupts high-speed operations.
Why is 45ns access time critical for 20–25MHz industrial PLCs?
20–25MHz PLCs operate on 40–50ns cycles. A 45ns access time aligns perfectly with this range, ensuring the SRAM delivers data exactly when the PLC needs it. Slower 60ns SRAMs create a 10–20ns lag per cycle, which accumulates over 1,000 cycles to cause 10–20ms delays. These delays misalign high-speed conveyors, miscalculate sensor readings, or trigger false safety alerts—leading to costly downtime or defective products.
How does the JDM-32 package improve reliability in harsh environments?
The JDM-32’s hermetic ceramic enclosure seals the SRAM in inert gas, blocking salt (coastal), dust (factories), or chemicals (oil/gas sites) that degrade plastic DIPs. Its J-lead pins form larger, vibration-resistant solder joints with PCBs—critical for factory robots or aircraft, where vibration breaks standard through-hole joints. This design ensures 10+ years of use vs. 2–3 years for plastic SRAMs.
What benefits does CMOS technology offer over TTL for this SRAM?
CMOS technology cuts power use by 62% (88mW vs. 230mW for TTL), extending backup battery life in critical systems. It also has a wider noise margin (0.4V–0.5V vs. TTL’s 0.3V), making it more resistant to electrical interference from factory motors or radar—reducing data corruption errors by 42% and minimizing unplanned downtime.
Is the SMJ68CE16L-45JDM 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 I/O levels are TTL-compatible (VIL ≤ 0.8V, VIH ≥ 2.0V), so no logic translators are needed. It also fits existing JDM-32 sockets, letting technicians replace older SRAMs without PCB modifications—saving time and avoiding costly infrastructure overhauls.