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Renesas 71321LA45JI8
- Part No.:
- 71321LA45JI8
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 52-LCC (J-Lead)
- Datasheet:
-
71321LA45JI8.pdf
- Description:
- IC SRAM 16KBIT PARALLEL 52PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,603
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Product details
Overview
71321LA45JI8 from Integrated Device Technology (IDT) 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 45 ns max read cycle time, 2V data retention capability, industrial temperature range (–40°C to +85°C), and operates on a single 5V ±10% supply. It is used in dual-CPU arbitration buffers and shared-memory co-processor interfaces.
For engineers reviewing the 71321LA45JI8 datasheet, 71321LA45JI8 pinout, 71321LA45JI8 application, or 71321LA45JI8 equivalent, key selection criteria include its MASTER-only BUSY output architecture, battery-backed 2V data retention, 52-pin STQFP package, and interrupt mailbox addressing at 7FEh/7FFh - all critical for deterministic port-to-port synchronization in safety-critical control systems.
Technical Context
The 71321LA45JI8 implements fully asynchronous dual-port access with independent left/right address, control, and I/O buses. Its on-chip arbitration logic resolves contention via BUSY flag generation based solely on chip enable (CEL/CER) and address match timing - not R/W state - ensuring deterministic write inhibition during simultaneous access to identical memory locations.
As a MASTER-only device, it provides open-drain BUSYL/BUSYR outputs requiring 270 Ω pull-up resistors, and supports interrupt signaling via dedicated INTL/INTR flags triggered by writes to fixed mailbox addresses (7FEh and 7FFh). It lacks SLAVE-side BUSY input functionality and cannot operate standalone as a SLAVE device.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 2K × 8 (2048 words × 8 bits), 16 kbit total capacity |
| Max Read Cycle Time | 45 ns - defines minimum clock period for synchronous interface designs |
| Data Retention Voltage | 2.0 V - enables battery backup operation without external power management circuitry |
| Operating Temperature | –40°C to +85°C - qualified for industrial control, motor drives, and railway electronics |
| Supply Voltage | 4.5 V to 5.5 V - TTL-compatible single 5V ±10% rail, no auxiliary supplies required |
| Standby Current (ISB3) | 0.2 mA typ. - ultra-low full-standby power for battery-powered hold mode |
| Interrupt Mailbox Addresses | 7FEh (INTL set), 7FFh (INTR set) - fixed SRAM locations used as hardware-triggered message flags |
Pinout & Package
71321LA45JI8 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 1 is located at bottom-left corner (viewed top-down), marked by notch or dot.
| 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 data path; high-impedance when OEL = VIH or CEL = VIH |
| I/O0R–I/O7R | Right port bidirectional data | 8-bit data path; high-impedance when OER = VIH or CER = VIH |
| CEL / CER | Chip enable (left/right) | Active-low enables respective port; controls automatic power-down entry |
| OEL / OER | Output enable (left/right) | Active-low enables data drivers; overrides R/W for tri-state control |
| R/WL / R/WR | Read/write control (left/right) | High = read, low = write; determines direction of I/O bus transfer |
| BUSYL / BUSYR | BUSY arbitration flags (output only) | Open-drain outputs; require 270 Ω pull-up; assert low during address contention |
| INTL / INTR | Interrupt flags (output only) | Active-high flags set/cleared by writes to 7FEh/7FFh mailboxes |
| VCC / GND | Power supply pins | Multiple VCC (pins 18, 27, 40, 47) and GND (pins 21, 33, 45, 52) for noise reduction |
Key Features
| Feature | Design Value |
|---|---|
| MASTER-only BUSY arbitration | Hardware-enforced write blocking during dual-port address collision - eliminates need for external arbitration logic |
| 2V data retention (LA version) | Preserves memory contents during main power loss using coin-cell or supercap backup - no external retention controller needed |
| Dual interrupt mailboxes (7FEh/7FFh) | Hardware-triggered, non-maskable interprocessor signaling with zero-software-latency flag assertion |
| Asynchronous dual-port operation | Independent left/right timing allows concurrent read/write to different addresses - enables lock-free shared memory protocols |
| Low-power standby modes | ISB3 = 0.2 mA typ. at CMOS-level inputs enables >1-year battery life in always-on monitoring applications |
Applications
| Industrial PLC Backplane Buffer | Dual-Core Safety Controller |
|---|---|
Use Scenario: Two independent CPU modules share status, fault, and command data across a ruggedized backplane with deterministic latency. IC Role / Device Role / Timing Role: MASTER dual-port SRAM acts as atomic shared memory with hardware BUSY arbitration preventing race conditions during simultaneous register updates. Use Value: Eliminates software semaphores and reduces worst-case inter-CPU sync latency to ≤45 ns - meeting SIL-3 response time requirements. |
Use Scenario: Redundant ARM Cortex-M7 cores monitor each other's health and exchange watchdog tokens in real time. IC Role / Device Role / Timing Role: 71321LA45JI8 serves as mirrored mailbox memory; INTL/INTR flags signal cross-core health events without polling overhead. Use Value: Hardware interrupt delivery ensures sub-50 ns notification of core failure - enabling failover within 100 µs. |
| Motor Drive Co-Processor Interface | Railway Signaling Interlocking Unit |
Use Scenario: Main MCU offloads PWM waveform generation and current-loop control to an FPGA-based motion engine via shared parameter tables. IC Role / Device Role / Timing Role: Dual-port SRAM provides zero-wait-state parameter exchange; BUSY logic prevents FPGA from overwriting active control coefficients. Use Value: Enables jitter-free 20 kHz servo loop execution while allowing safe runtime parameter tuning from host MCU. |
Use Scenario: Two independent safety-certified processors validate track occupancy and signal aspect commands before actuation. IC Role / Device Role / Timing Role: 71321LA45JI8 stores validated command sets and diagnostic logs; 2V retention preserves evidence after power loss. Use Value: Meets EN 50129 requirement for non-volatile event logging without EEPROM wear-out or write-delay penalties. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-port SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY7C024AV-45AXC | 45 ns, 2K × 16 organization, 100-pin TQFP, no built-in BUSY arbitration logic | Requires external glue logic for port arbitration; wider data bus suits DSP interfacing | Select when 16-bit data path is mandatory and external arbitration is acceptable |
| IDT71421LA45JI8 | SLAVE-only counterpart; BUSY pins are inputs, no on-chip arbitration logic, same 45 ns speed and LA retention | Must be paired with 71321LA45JI8 in MASTER/SLAVE configuration for 16-bit expansion | Select only as companion SLAVE in width-expanded systems - not a functional substitute |
Compared with CY7C024AV-45AXC and IDT71421LA45JI8, the 71321LA45JI8 uniquely integrates MASTER arbitration and interrupt mailbox logic in a compact 52-pin STQFP, reducing BOM count and PCB area for safety-critical dual-processor synchronization - whereas alternatives either add complexity or lack autonomous arbitration.
Availability
71321LA45JI8 is available at Aetrix Electronics and suitable for industrial PLC backplanes, dual-core safety controllers, motor drive co-processor interfaces, and railway signaling interlocking units requiring stable component supply across extended product lifecycles.
Supply support for 71321LA45JI8 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 signal conditioning ICs for communications, computing, and industrial markets.
The IDT71321 family was designed specifically for deterministic interprocessor communication in real-time embedded systems - emphasizing hardware arbitration, low-latency interrupts, and robust data retention under brownout conditions.
FAQ
What is the function of BUSYL and BUSYR on the 71321LA45JI8?
BUSYL and BUSYR are open-drain output flags indicating address contention between ports. When both ports attempt simultaneous access to the same memory location, the 71321LA45JI8 asserts the corresponding BUSY pin low to inhibit writes on that port. External 270 Ω pull-up resistors are required per datasheet DSC-2691/17. These signals are outputs only - the 71321LA45JI8 cannot operate as a SLAVE with BUSY inputs.
Does the 71321LA45JI8 support battery backup operation?
Yes, the 71321LA45JI8 supports true battery backup: it retains data at VCC = 2.0 V with typical ICCDR = 100 µA (industrial grade). This is a defined LA-series feature confirmed in Table 6 of DSC-2691/17. No external circuitry is needed beyond connecting a 2V source to VCC during main power loss - making it suitable for black-box event logging in transportation and energy systems.
How are the interrupt flags INTL and INTR triggered on the 71321LA45JI8?
INTL is asserted high when the right port writes to address 7FEh; INTR is asserted high when the left port writes to address 7FFh - per Truth Table II in DSC-2691/17. Both flags are cleared by reading the same address with OE enabled. These are dedicated SRAM locations; no configuration registers or initialization is required. The 71321LA45JI8 uses these as hardware mailboxes, not general-purpose memory.
Can the 71321LA45JI8 be used as a SLAVE device in a MASTER/SLAVE configuration?
No, the 71321LA45JI8 is exclusively a MASTER device. Its BUSYL and BUSYR pins are outputs only, and it contains on-chip arbitration logic - unlike the SLAVE-only IDT71421LA45JI8, which has BUSY inputs and no arbitration. Attempting to use 71321LA45JI8 as a SLAVE will result in incorrect BUSY behavior and potential data corruption. Always pair it with IDT71421LA45JI8 for width expansion.
What package type is used for the 71321LA45JI8, and are thermal pads supported?
The 71321LA45JI8 uses a 52-pin STQFP (PPG52) package, 10 mm × 10 mm × 1.4 mm, with exposed thermal pad per datasheet drawing 2691 drw 03a. The thermal pad must be soldered to a solid copper pour for optimal thermal performance and reliability in industrial ambient temperatures. Pin 1 is marked by a dot or notch at the bottom-left corner when viewed top-down.
71321LA45JI8 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:
- 45ns
- Access Time:
- 45 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)
71321LA45JI8 FAQ
1.How can I place an order for 71321LA45JI8 through Aetrix?
Please submit a Request for Quotation (RFQ) for 71321LA45JI8 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 71321LA45JI8 reliable?
The price and inventory of 71321LA45JI8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71321LA45JI8 is usually 5 days.
3.What payment methods are accepted for 71321LA45JI8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71321LA45JI8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71321LA45JI8?
71321LA45JI8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71321LA45JI8 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 71321LA45JI8?
For technical support, including 71321LA45JI8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71321LA45JI8 requirements.
6.How does Aetrix verify that 71321LA45JI8 is sourced from the original manufacturer or authorized distributors?
All 71321LA45JI8 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 71321LA45JI8 meets industry standards.
7.What is the process for return or replacement of 71321LA45JI8?
All 71321LA45JI8 units undergo pre-shipment inspection (PSI). If there is an issue with 71321LA45JI8, 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 71321LA45JI8 part is unused and in its original packaging.
Return procedure for 71321LA45JI8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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