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Renesas 71421LA55JI8
- Part No.:
- 71421LA55JI8
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 52-LCC (J-Lead)
- Datasheet:
-
71421LA55JI8.pdf
- Description:
- IC SRAM 16KBIT PARALLEL 52PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,597
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Product details
Overview
71421LA55JI8 from IDT (now part of Renesas) is a high-speed 2K × 8 dual-port static RAM configured as a SLAVE device in MASTER/SLAVE memory expansion systems, supporting asynchronous port-to-port communication with BUSY input and interrupt flags (INTL/INTR), 55 ns max read cycle time, industrial temperature range (–40°C to +85°C), and 2 V battery backup data retention - used in real-time interprocessor communication buffers and redundant control subsystems.
For engineers reviewing the 71421LA55JI8 datasheet, 71421LA55JI8 pinout, 71421LA55JI8 application, or 71421LA55JI8 equivalent, key selection considerations include its role as a SLAVE dual-port SRAM requiring external BUSY arbitration from a MASTER (e.g., IDT71321), TTL-compatible 5 V ±10% supply, 64-pin TQFP package, and support for interrupt-driven mailbox messaging at addresses 7FEh/7FFh.
Technical Context
The 71421LA55JI8 implements fully asynchronous dual-port access with independent left/right address, control, and I/O buses; it lacks on-chip arbitration logic and instead accepts BUSY as an input to inhibit writes during contention - unlike the MASTER IDT71321 which generates BUSY. Its interrupt function uses dedicated mailbox addresses (7FEh for INTL set, 7FFh for INTR set) with edge-triggered flag assertion and software-clear capability.
Designed for low-power industrial operation, the LA variant delivers 1 µA typical standby current (ISB3) at full CMOS-level disable and retains data down to 2 V VCC, enabling battery-backed operation without external power management circuitry. All timing parameters - including tBDD (BUSY disable to valid data), tWDD (write pulse to data delay), and tDDD (write-to-read data delay) - are specified for SLAVE-specific BUSY input behavior and port-to-port synchronization.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 2K × 8 (2048 words × 8 bits), 16 kbit total capacity |
| Access Time (tAA) | 55 ns max - defines minimum address hold before valid data appears |
| Read Cycle Time (tRC) | 55 ns max - sets minimum interval between successive read operations |
| Data Retention Voltage | 2.0 V min - enables reliable non-volatile storage during main power loss |
| Standby Current (ISB3) | 5 µA typ. - ultra-low power consumption when both ports fully disabled |
| Operating Temperature | –40°C to +85°C - qualified for industrial embedded control and automation |
| Supply Voltage | 4.5 V to 5.5 V - TTL-compatible single 5 V ±10% rail, no auxiliary supplies needed |
Pinout & Package
71421LA55JI8 is packaged in a 64-pin Thin Quad Flat Package (TQFP), body size 14 mm × 14 mm × 1.4 mm, lead pitch 0.5 mm, RoHS-compliant and green-qualified. Pin functions are defined per the official IDT pinout diagram for PNG64/PPG64 packages.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0L–A10L | Left port address inputs | 11-bit address bus for left-side memory access (0–2047) |
| A0R–A10R | Right port address inputs | 11-bit address bus for right-side memory access (0–2047) |
| I/O0L–I/O7L | Left port bidirectional data | 8-bit data path; tri-stated when OEL = VIH or CEL = VIH |
| I/O0R–I/O7R | Right port bidirectional data | 8-bit data path; tri-stated when OER = VIH or CER = VIH |
| CEL / CER | Chip enable (left/right) | Active-low enables respective port; controls power-down mode |
| OEL / OER | Output enable (left/right) | Active-low enables output drivers; high-Z when deasserted |
| R/WL / R/WR | Read/write control (left/right) | High = read, low = write; determines direction of I/O bus |
| BUSYL / BUSYR | BUSY input (SLAVE only) | Active-low write-inhibit signal from MASTER; must be pulled high externally |
| INTL / INTR | Interrupt flags (open-drain) | Active-low outputs indicating mailbox writes (7FEh/7FFh); require 270 Ω pull-up |
| VCC / GND | Power and ground | Multiple VCC/GND pins ensure stable decoupling across high-speed operation |
Key Features
| Feature | Design Value |
|---|---|
| SLAVE-only BUSY input interface | Enables seamless integration into MASTER/SLAVE arrays without external arbitration logic |
| Dual-mailbox interrupt architecture | Hardware-set, software-cleared flags at fixed addresses (7FEh/7FFh) simplify interprocessor signaling |
| 2 V data retention | Preserves memory contents during brown-out or backup battery operation without external circuitry |
| 55 ns industrial-grade timing | Guaranteed performance over –40°C to +85°C, eliminating derating in harsh environments |
| 64-pin TQFP with 0.5 mm pitch | Compact footprint compatible with automated SMT assembly and high-density PCB layouts |
Applications
| Industrial PLC Communication Buffer | Avionics Dual-Processor Data Exchange |
|---|---|
Use Scenario: Real-time data sharing between safety-critical and non-safety-critical processor domains in programmable logic controllers. IC Role / Device Role / Timing Role: SLAVE dual-port SRAM synchronizes writes from MASTER CPU while allowing independent reads by monitoring CPU, using BUSY input to prevent corruption. Use Value: Eliminates need for external arbitration logic and guarantees atomic mailbox updates via hardware-interrupt flags at 7FEh/7FFh. |
Use Scenario: Cross-domain message passing between flight control and navigation processors in certified avionics systems. IC Role / Device Role / Timing Role: Provides deterministic, low-latency shared memory with 55 ns access and 2 V data retention for fault-tolerant state capture. Use Value: Enables battery-backed snapshot storage during power transitions, meeting DO-254 timing and reliability requirements. |
| Redundant Motor Control Subsystem | Medical Imaging Real-Time Frame Buffer |
Use Scenario: Coordinating primary and backup motor controllers in servo drives where simultaneous access must be collision-free. IC Role / Device Role / Timing Role: SLAVE device receives BUSY from MASTER to block conflicting writes, ensuring consistent torque command updates. Use Value: Prevents race conditions during failover events without software overhead or additional gate logic. |
Use Scenario: High-throughput buffering of ultrasound or MRI frame data between acquisition FPGA and display processor. IC Role / Device Role / Timing Role: Dual-port architecture allows concurrent write (acquisition side) and read (rendering side) at 55 ns speed. Use Value: Sustains >18 MB/s bandwidth with zero wait states, avoiding frame drops during real-time imaging. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-port SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| IDT71421SA55JI8 | No battery backup; higher ISB3 (15 µA vs. 5 µA); same timing and pinout | Suitable for mains-powered systems without retention requirement | Select when 2 V data retention is unnecessary and lower cost is prioritized |
| Cypress CY7C1371DV33-55BGXI | 3.3 V supply; different pinout (119-ball BGA); no BUSY arbitration logic | Requires redesign for voltage translation and layout; no native MASTER/SLAVE expansion | Consider only if migrating to 3.3 V ecosystem and accepting added system complexity |
Compared with IDT71421SA55JI8, the 71421LA55JI8 adds critical 2 V data retention and cuts standby current by 67%, making it irreplaceable in battery-backed industrial control; versus CY7C1371DV33-55BGXI, it offers drop-in compatibility in 5 V systems with integrated BUSY-based arbitration - eliminating external glue logic.
Availability
71421LA55JI8 is available at Aetrix Electronics and suitable for industrial PLC communication buffers, avionics dual-processor data exchange, and redundant motor control subsystems requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.
Supply support for 71421LA55JI8 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
IDT (Integrated Device Technology), now part of Renesas Electronics, is a fabless semiconductor company specializing in high-performance timing, memory, and interface solutions for communications, computing, and industrial markets.
The IDT71421 family was designed specifically for deterministic, low-latency interprocessor communication in real-time embedded systems - emphasizing hardware arbitration, interrupt-driven messaging, and industrial-grade reliability without software intervention.
FAQ
What is the role of 71421LA55JI8 in a MASTER/SLAVE dual-port SRAM configuration?
The 71421LA55JI8 serves exclusively as a SLAVE device: it accepts BUSY as an input to inhibit writes during address contention, relies on an external MASTER (e.g., IDT71321) for arbitration, and supports interrupt flag generation via mailbox writes to 7FEh/7FFh. It does not generate BUSY or perform on-chip arbitration - that functionality resides solely in the MASTER. This division ensures scalable, glitch-free width expansion in 16-bit-or-wider memory systems.
Does 71421LA55JI8 support true 2 V operation or only data retention at 2 V?
71421LA55JI8 supports data retention at 2.0 V minimum (VDR), but functional operation requires VCC between 4.5 V and 5.5 V. At 2 V, only static data hold is guaranteed - no read/write cycles, no interrupt assertion, and no BUSY response occur. The LA suffix explicitly denotes this battery backup capability, distinct from SA versions which lack retention below 4.5 V. ICC and timing specs apply only within the 4.5–5.5 V operating range.
How are the INTL and INTR interrupt flags cleared in 71421LA55JI8?
In 71421LA55JI8, INTL is cleared by reading from address 7FEh with CEL = OEL = VIL (R/WL is don't-care); INTR is cleared by reading from address 7FFh with CER = OER = VIL (R/WR is don't-care). Both flags are open-drain and require external 270 Ω pull-up resistors. The interrupt remains asserted until the corresponding read access occurs - no auto-clear or timer-based reset is implemented. This design enables precise software-controlled acknowledgment.
Can 71421LA55JI8 operate without a MASTER device in a standalone configuration?
Yes - 71421LA55JI8 can operate as a standalone dual-port SRAM: both ports function independently with full read/write capability when BUSYL and BUSYR are held high (via 270 Ω pull-ups). BUSY arbitration is optional; disabling it removes write inhibition but retains all memory, interrupt, and timing functionality. However, simultaneous writes to the same address from both ports remain undefined and must be avoided in standalone use via software coordination or external logic.
What is the significance of the 'J' and 'I8' suffixes in 71421LA55JI8?
In 71421LA55JI8, 'J' denotes the 64-pin TQFP package (PNG64/PPG64), and 'I8' specifies the industrial temperature grade (–40°C to +85°C) with screening for extended reliability. The '55' indicates 55 ns maximum access time, 'LA' confirms low-power battery-retention capability, and '71421' identifies the SLAVE dual-port SRAM family. This full ordering code ensures unambiguous identification of speed, package, temperature, and functional variant - critical for obsolescence-sensitive industrial designs.
71421LA55JI8 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)
71421LA55JI8 FAQ
1.How can I place an order for 71421LA55JI8 through Aetrix?
Please submit a Request for Quotation (RFQ) for 71421LA55JI8 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 71421LA55JI8 reliable?
The price and inventory of 71421LA55JI8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71421LA55JI8 is usually 5 days.
3.What payment methods are accepted for 71421LA55JI8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71421LA55JI8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71421LA55JI8?
71421LA55JI8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71421LA55JI8 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 71421LA55JI8?
For technical support, including 71421LA55JI8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71421LA55JI8 requirements.
6.How does Aetrix verify that 71421LA55JI8 is sourced from the original manufacturer or authorized distributors?
All 71421LA55JI8 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 71421LA55JI8 meets industry standards.
7.What is the process for return or replacement of 71421LA55JI8?
All 71421LA55JI8 units undergo pre-shipment inspection (PSI). If there is an issue with 71421LA55JI8, 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 71421LA55JI8 part is unused and in its original packaging.
Return procedure for 71421LA55JI8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
71421LA55JI8 Tags
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