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Renesas 71321SA55JI8
- Part No.:
- 71321SA55JI8
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 52-LCC (J-Lead)
- Datasheet:
-
71321SA55JI8.pdf
- Description:
- IC SRAM 16KBIT PARALLEL 52PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,238
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Product details
Overview
71321SA55JI8 from IDT (Integrated Device Technology) is a high-speed 2K × 8 dual-port static RAM with interrupt and BUSY arbitration logic, designed as a MASTER device for interprocessor communication in real-time embedded systems. It features 55 ns max read cycle time, TTL-compatible 5 V ±10% operation, industrial temperature range (–40°C to +85°C), and supports 16-bit-or-wider memory expansion via SLAVE IDT71421 pairing in multiprocessing architectures.
For engineers reviewing the 71321SA55JI8 datasheet, 71321SA55JI8 pinout, 71321SA55JI8 application, or 71321SA55JI8 equivalent, key selection criteria include port-to-port arbitration timing (tBAA/tBDD ≤ 30 ns), open-drain BUSY output requiring 270 Ω pull-up, interrupt mailbox addressing (7FEH/7FFH), and compatibility with 52-pin STQFP (PPG52) packaging for space-constrained industrial control modules.
Technical Context
The 71321SA55JI8 implements fully asynchronous dual-port access with independent left/right address, control, and I/O buses - enabling concurrent read/write operations without external synchronization. Its on-chip arbitration logic resolves contention using chip-enable and address-match detection (tAPS = 5 ns), asserting BUSYL/BUSYR outputs to inhibit writes during conflict.
Interrupt functionality uses dedicated SRAM mailboxes: INTL asserts when right port writes to address 7FEH; INTR asserts when left port writes to 7FFH. Both flags are cleared by reading the same location. The device operates in active mode (ICC ≤ 65 mA typ.) or full standby (ISB3 ≤ 1.0 mA typ.) depending on CE-level inputs and input voltage thresholds.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 2K × 8 bits (2048 words × 8 data lines) - provides compact shared memory buffer for dual-CPU coordination |
| Max Read Cycle Time | 55 ns - guarantees deterministic latency for real-time inter-processor messaging in industrial PLCs |
| Supply Voltage | 4.5 V to 5.5 V - compatible with legacy 5 V TTL logic families without level-shifting |
| Operating Temperature | –40°C to +85°C - qualified for under-hood automotive ECUs and factory-floor controllers |
| Standby Current (ISB3) | 1.0 mA max at full CMOS disable - enables low-power sleep modes in battery-backed systems |
| BUSY Output Type | Open-drain (requires 270 Ω pull-up) - allows wired-AND of multiple BUSY signals in expanded arrays |
| Interrupt Mailbox Addresses | 7FEH (INTL set), 7FFH (INTR set) - fixed-location hardware signaling avoids software polling overhead |
Pinout & Package
71321SA55JI8 is packaged in a 52-pin STQFP (PPG52) measuring 10 mm × 10 mm × 1.4 mm, with exposed thermal pad and lead-free RoHS-compliant finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0L–A10L | Left port address inputs | 11-bit address bus for left-side memory access (000H–7FFH) |
| A0R–A10R | Right port address inputs | 11-bit address bus for right-side memory access (000H–7FFH) |
| I/O0L–I/O7L | Left port bidirectional data | 8-bit parallel data path; high-impedance when OEL = VIH or CEL = VIH |
| I/O0R–I/O7R | Right port bidirectional data | 8-bit parallel data path; high-impedance when OER = VIH or CER = VIH |
| CEL / CER | Chip enable (left/right) | Active-low enables respective port; controls power-down entry (ISB1–ISB4 states) |
| OEL / OER | Output enable (left/right) | Active-low enables data outputs; overrides R/W state for tristate control |
| R/WL / R/WR | Read/write control (left/right) | High = read, low = write; determines direction of I/O bus data flow |
| BUSYL / BUSYR | BUSY flag (output only) | Open-drain outputs indicating port contention; require external 270 Ω pull-up per IDT spec |
| INTL / INTR | Interrupt flags (output only) | Active-high interrupt indicators tied to mailbox writes at 7FEH/7FFH |
| VCC / GND | Power supply pins | Multiple VCC/GND pairs ensure stable 5 V distribution and noise immunity across high-speed switching |
Key Features
| Feature | Design Value |
|---|---|
| On-chip port arbitration logic | Resolves simultaneous access conflicts without external logic; tAPS = 5 ns ensures priority resolution before write initiation |
| Dual interrupt mailboxes | Hardware-accelerated interprocessor signaling via fixed SRAM addresses (7FEH/7FFH), eliminating polling latency |
| Master-only BUSY output | Enables scalable width expansion: one 71321SA55JI8 drives BUSY to multiple IDT71421 slaves for coherent 16+ bit memory systems |
| 55 ns industrial-grade timing | Guaranteed performance over –40°C to +85°C, supporting deterministic response in motion control and robotics |
| Low-power standby modes | ISB3 ≤ 1.0 mA at full CMOS disable allows battery backup operation in LA variants (not applicable here, but architecture-shared) |
Applications
| Industrial PLC Memory Buffer | Automotive Engine Control Unit |
|---|---|
Use Scenario: Dual-CPU architecture where one processor handles I/O scanning and another executes control algorithms, sharing status and command data. IC Role / Device Role / Timing Role: MASTER dual-port SRAM providing synchronized, contention-free memory access with hardware BUSY arbitration. Use Value: Eliminates software semaphores and reduces inter-CPU latency to ≤30 ns (tBDD), improving scan cycle consistency in safety-critical applications. | Use Scenario: Real-time coordination between main ECU microcontroller and dedicated diagnostics co-processor accessing shared sensor calibration tables. IC Role / Device Role / Timing Role: High-reliability shared memory with interrupt-driven event notification (INTL/INTR) for fault reporting and parameter updates. Use Value: Enables immediate fault flagging via 7FEH/7FFH mailboxes, reducing diagnostic response time to <25 ns (tINS), critical for OBD-II compliance. |
| Avionics Data Acquisition System | Medical Imaging Subsystem |
Use Scenario: Time-triggered acquisition engine writing raw ADC samples while analysis processor reads completed frames for FFT processing. IC Role / Device Role / Timing Role: Asynchronous dual-port buffer with deterministic 55 ns read cycle and tWDD ≤ 80 ns write-to-read propagation. Use Value: Guarantees zero-data-loss frame handoff under worst-case contention, meeting DO-254 timing closure requirements. | Use Scenario: MRI subsystem where FPGA-based image reconstruction engine shares pixel buffers with ARM-based UI controller for real-time display updates. IC Role / Device Role / Timing Role: Compact 2K × 8 shared memory with industrial temp rating and open-drain BUSY for multi-SRAM array coherence. Use Value: Supports hot-swappable module designs via PPG52 footprint; BUSY wired-AND enables seamless expansion to 32-bit data paths without layout changes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-port SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY7C136-55JC | 55 ns access, 2K × 8, but lacks integrated BUSY arbitration and interrupt logic; requires external glue logic for master/slave coordination | Suitable for simpler dual-CPU systems without hardware contention management needs | Select when cost sensitivity outweighs need for arbitration/interrupt acceleration and board space permits discrete logic |
| IDT71421SA55JI8 | Same speed/package, but SLAVE-only: BUSY pins are inputs (not outputs); no on-chip arbitration logic; cannot operate standalone as MASTER | Used only in conjunction with 71321SA55JI8 for 16-bit+ memory expansion | Required companion part for width expansion - not a functional substitute, but essential for scalable system design |
Compared with CY7C136-55JC, 71321SA55JI8 delivers hardware-accelerated arbitration and interrupt signaling in a single package, reducing BOM count and timing uncertainty; versus IDT71421SA55JI8, it serves as the sole MASTER controller with full BUSY generation capability - making it irreplaceable in standalone dual-processor buffer roles.
Availability
71321SA55JI8 is available at Aetrix Electronics and suitable for industrial PLC memory buffers, automotive engine control units, avionics data acquisition systems, and medical imaging subsystems requiring stable component supply across extended product lifecycles.
Supply support for 71321SA55JI8 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Integrated Device Technology (IDT), now part of Renesas Electronics, is a fabless semiconductor company specializing in timing, memory interface, RF, and sensor solutions for communications, computing, and industrial markets.
The IDT71321 family was engineered specifically for deterministic interprocessor communication in real-time embedded systems, emphasizing hardware arbitration, interrupt offload, and industrial-grade reliability over generic SRAM performance.
FAQ
What is the function of the BUSY pins on the 71321SA55JI8?
The BUSYL and BUSYR pins on the 71321SA55JI8 are open-drain outputs that signal port contention during simultaneous access to the same memory location. When asserted (pulled low), they inhibit writes on the respective port. Per IDT documentation, these pins require a 270 Ω external pull-up resistor to VCC and are used exclusively in MASTER configuration - unlike SLAVE devices where BUSY is an input. This behavior is intrinsic to the 71321SA55JI8's arbitration logic.
Does the 71321SA55JI8 support battery backup operation?
No, the 71321SA55JI8 does not support battery backup operation. Battery retention (2 V data hold) is exclusive to LA-suffixed variants (e.g., 71321LA55JI8). The 'SA' suffix denotes standard active power consumption (ICC ≤ 65 mA typ.), with full standby current ISB3 ≤ 1.0 mA - sufficient for low-power sleep but not for long-term VCC loss. This distinction is explicitly defined in IDT's ordering information and DC characteristics tables.
How are interrupts generated and cleared in the 71321SA55JI8?
Interrupts in the 71321SA55JI8 are generated by writes to dedicated SRAM mailboxes: INTL asserts when the right port writes to address 7FEH; INTR asserts when the left port writes to 7FFH. Clearing occurs by reading the same address - e.g., reading 7FEH clears INTL. This mechanism is implemented in hardware per Truth Table II and requires no firmware intervention, ensuring sub-25 ns interrupt latency (tINS) as specified in AC characteristics tables.
Can the 71321SA55JI8 operate with mixed voltage interfaces?
No, the 71321SA55JI8 is strictly a 5 V ±10% device with TTL-compatible input thresholds (VIH ≥ 2.2 V, VIL ≤ 0.8 V) and no internal level-shifting. All control, address, and I/O signals must be referenced to the same 5 V supply. Interfacing with 3.3 V or 1.8 V logic requires external translators - confirmed by Recommended DC Operating Conditions (VCC = 4.5–5.5 V only) and absence of multi-voltage I/O support in functional description.
What package type is used for the 71321SA55JI8?
The 71321SA55JI8 uses a 52-pin STQFP package designated PPG52, measuring 10 mm × 10 mm × 1.4 mm with an exposed thermal pad. This is confirmed in Pin Configuration diagrams (page 3, "PPG52(4) 52-Pin STQFP Top View") and ordering information notes. It is distinct from PLCC (PLG52) and 64-pin TQFP variants - the 'J' in the part number explicitly denotes the PPG52 body style per IDT's packaging nomenclature.
71321SA55JI8 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 52-LCC (J-Lead)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Volatile
- Memory Format:
- SRAM
- Technology:
- SRAM - Dual Port, Asynchronous
- Memory Size:
- 16Kbit
- Memory Organization:
- 2K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 55ns
- Access Time:
- 55 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 52-PLCC (19.13x19.13)
71321SA55JI8 FAQ
1.How can I place an order for 71321SA55JI8 through Aetrix?
Please submit a Request for Quotation (RFQ) for 71321SA55JI8 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for 71321SA55JI8 reliable?
The price and inventory of 71321SA55JI8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71321SA55JI8 is usually 5 days.
3.What payment methods are accepted for 71321SA55JI8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71321SA55JI8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71321SA55JI8?
71321SA55JI8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71321SA55JI8 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for 71321SA55JI8?
For technical support, including 71321SA55JI8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71321SA55JI8 requirements.
6.How does Aetrix verify that 71321SA55JI8 is sourced from the original manufacturer or authorized distributors?
All 71321SA55JI8 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 71321SA55JI8 meets industry standards.
7.What is the process for return or replacement of 71321SA55JI8?
All 71321SA55JI8 units undergo pre-shipment inspection (PSI). If there is an issue with 71321SA55JI8, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The 71321SA55JI8 part is unused and in its original packaging.
Return procedure for 71321SA55JI8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
71321SA55JI8 Tags
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