SMJ68CE16S-55JDM Legacy Hermetic 128K×8 CMOS Static RAM (SRAM) Overview
The SMJ68CE16S-55JDM 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 trusted portfolio of hermetic memory components, it delivers snelle, niet-verversende tijdelijke gegevensopslag—ideal for applications where speed, environmental resilience, and legacy compatibility are non-negotiable. Its J-lead DIP (JDM-32) package, 55ns access time, and wide temperature range make it a staple for maintaining older electronics that demand consistent performance in harsh conditions. IC-fabrikant biedt deze geheugencomponent van industriële kwaliteit aan als onderdeel van zijn portfolio van vertrouwde Texas Instruments halfgeleiders.
Technical Parameters for SMJ68CE16S-55JDM Industrial SRAM
| Parameter | Waarde | Eenheid |
|---|---|---|
| Functie | 128K×8 statisch willekeurig toegankelijk geheugen (SRAM) | |
| Geheugenconfiguratie | 131,072 × 8 | Bits (1024 Kbits / 128 Kbytes totaal) |
| Toegangstijd (Max) | 55 | ns (bij 5V, 25°C) |
| Bereik voedingsspanning | 4,5 tot 5,5 | V (enkele voeding, CMOS-compatibel) |
| Ruststroomdissipatie (typisch) | 85 | mW (bij 5V, onbelast) |
| Type verpakking | JDM-32 (J-Lead Dual In-Line Package, 32-pins, hermetisch keramisch) | |
| Bedrijfstemperatuurbereik | -55 tot +125 | °C (industriële/militaire kwaliteit) |
Belangrijkste functionele kenmerken
| Kenmerk | Specificatie |
|---|---|
| Type interface | 8-bits parallel (CMOS-compatibele adres-/data-/besturingspennen) |
| Compatibiliteit logicafamilie | TI 74HC/74HCT CMOS, 54LS TTL (ondersteuning voor mixed-signal legacy systemen) |
| Geluidsmarge (min) | 0,4V (laag niveau); 0,5V (hoog niveau) (industriële stabiliteit) |
| Uitgangsstroom | -8mA (sink); +4mA (source) (typisch, CMOS-conform) |
| Betrouwbaarheidsnormen | Voldoet aan MIL-STD-883 (hermetisch, temperatuurbestendig, ESD-bescherming) |
Voordelen ten opzichte van alternatieve legacygeheugenoplossingen
The SMJ68CE16S-55JDM 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 70ns plastic SRAMs with this model in our 18MHz aerospace test equipment, and data logging errors dropped by 40%,” confirms a senior engineer at a leading defense electronics firm.
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Its 55ns access time is 21% faster than 70ns SRAMs, eliminating data lag in mid-to-high-speed legacy systems (15–20MHz controllers). For example, a factory sensor hub using a 70ns SRAM took 1.4ms to process 300 8-bit sensor data points; switching to this 55ns model cut processing time to 1.1ms. This ensured the PLC received data in time to adjust motor speeds, reducing defective parts by 28% in high-speed assembly lines.
As a CMOS SRAM, it uses 65% less power than TTL alternatives (85mW vs. 240mW), extending backup battery life in industrial systems by 25% during power outages. This is critical for safety-critical equipment like emergency shutdown controllers, where prolonged battery life prevents operational gaps.
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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. Its -55°C to +125°C temperature range also outperforms commercial-grade SRAMs (0°C–70°C), ensuring performance in freezing warehouse sensors or hot engine bays.
Typical Applications of SMJ68CE16S-55JDM
The SMJ68CE16S-55JDM excels in legacy and mission-critical systems where speed, ruggedness, and compatibility are non-negotiable. Key use cases include:
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- Lucht- en ruimtevaart en defensie (gegevensbuffers voor vliegtuigelektronica, geheugen voor raketgeleidingssystemen, loggers voor satellietgrondstations)
- Industrial Automation (15–20MHz legacy PLCs, factory sensor hubs, high-speed production line controllers)
- Testen en meten (robuuste signaalgeneratoren, testapparatuur voor omgevingsbelasting, verouderd oscilloscoopgeheugen)
- Energie en vermogen (controllers voor olie-/gasbronnen, sensorgeheugens voor windturbines, dataprocessors voor hoogspanningsstations)
- Beveiliging en bewaking (sensorgegevensbuffers voor militaire perimeters, oude opnamemodules voor buitencamera's)
Texas Instruments' expertise in hermetisch CMOS-geheugen
As a Texas Instruments product, the SMJ68CE16S-55JDM 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.
Veelgestelde vragen (FAQ)
What is the SMJ68CE16S-55JDM, and how does it work in legacy systems?
The SMJ68CE16S-55JDM 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 55ns, syncing with 15–20MHz legacy controllers (e.g., 54LS TTL PLCs) to ensure real-time performance without lag.
Why is 55ns access time important for 15–20MHz industrial PLCs?
15–20MHz PLCs process data at intervals of 50–67ns per cycle. A 55ns access time aligns with this range, ensuring the SRAM delivers data in time for the PLC to execute control commands. Slower 70ns SRAMs create a 10–20ns lag per cycle, which accumulates over 1,000 cycles to cause 10–20ms delays—enough to disrupt production line sync, misalign conveyors, and produce defective parts.
How does the JDM-32 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-32’s hermetic ceramic enclosure seals the SRAM in an inert gas, blocking contaminants from reaching the chip. 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.
Welke voordelen biedt CMOS-technologie voor dit SRAM in vergelijking met TTL?
CMOS technology reduces power consumption by 65% (85mW vs. 240mW 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 40% and reducing unplanned downtime.
Is the SMJ68CE16S-55JDM 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, simplifying integration. It also fits existing JDM-32 sockets, so technicians can replace older SRAMs without modifying PCBs—saving time and avoiding costly redesigns.