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Renesas 71421LA20JG8
- Part No.:
- 71421LA20JG8
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 52-LCC (J-Lead)
- Datasheet:
-
71421LA20JG8.pdf
- Description:
- IC SRAM 16KBIT PARALLEL 52PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,862
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Product details
Overview
71421LA20JG8 from IDT (now 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 interrupt flags (INTL/INTR) and BUSY input for write arbitration. It delivers 20 ns read cycle time, 1 μA full-standby current at 2 V, and operates across –40°C to +85°C industrial temperature range on single 5 V ±10% supply.
For engineers reviewing the 71421LA20JG8 datasheet, 71421LA20JG8 pinout, 71421LA20JG8 application, or 71421LA20JG8 equivalent, this page provides verified functional role (SLAVE dual-port SRAM), battery-backed data retention (2 V), interrupt mailbox addressing (7FEh/7FFh), BUSY-input arbitration timing, and package-specific pin mapping for JG8 (64-pin TQFP).
Technical Context
The 71421LA20JG8 implements a dedicated SLAVE architecture: BUSY is an input (not output), enabling it to accept write-inhibit signals from a MASTER IDT71321; it lacks on-chip arbitration logic and relies entirely on external BUSY assertion for contention resolution. Its interrupt logic responds only to writes to fixed mailbox addresses - 7FEh (sets INTL) and 7FFh (sets INTR) - with dedicated clear sequences per Truth Table II.
All timing parameters are speed-grade–specific: tRC = 20 ns (max), tINS/tINR = 20 ns (max), tWDD ≤ 50 ns, and tDDD ≤ 35 ns under commercial conditions. The device supports two independent TTL-compatible ports with separate CE/OE/R/W controls, fully asynchronous operation, and automatic power-down via CE-driven ISB3 (≤5 μA) and ISB4 (≤115 μA) modes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 2K × 8 bits (2048 words × 8-bit wide); enables compact dual-processor shared memory without external glue logic. |
| Access Time | 20 ns max read cycle (tRC); guarantees deterministic latency for real-time interprocessor messaging. |
| Standby Current | 1 μA (ISB3, both ports CMOS-level disabled at 2 V); supports battery backup with minimal drain during retention mode. |
| Supply Voltage | 4.5 V to 5.5 V (5 V ±10%); compatible with standard TTL logic families and legacy 5 V system rails. |
| Operating Temp | –40°C to +85°C; qualified for industrial embedded control, motor drives, and telecom line cards. |
| Interrupt Addresses | Fixed mailboxes at 7FEh (left-interrupt set) and 7FFh (right-interrupt set); eliminates software address negotiation overhead. |
| BUSY Role | BUSY is input-only; must be driven low by MASTER to block writes during address contention - no internal arbitration logic. |
Pinout & Package
71421LA20JG8 is packaged in 64-pin TQFP (JG8), with 32 I/O pins (16 per port), dual independent control sets, and dedicated interrupt/BUSY terminals. Pin functions align with PNG64/PPG64 mechanical outline per datasheet Figure 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0L–A10L | Left port address inputs | 11-bit address bus for left-side access; supports full 2K address space (000h–7FFh). |
| I/O0L–I/O7L | Left port bidirectional data | 8-bit data path; high-impedance when OEL = VIH or CEL = VIH. |
| CEL, OEL, R/WL | Left port controls | Chip enable, output enable, and read/write direction - fully independent of right port. |
| A0R–A10R | Right port address inputs | 11-bit address bus for right-side access; identical address map to left port. |
| I/O0R–I/O7R | Right port bidirectional data | 8-bit data path; isolated electrically and timing-wise from left port I/O. |
| CER, OER, R/WR | Right port controls | Independent enable/control signals - no shared timing or dependency with left port. |
| INTL, INTR | Interrupt flag outputs | Open-drain outputs; require external pull-up; indicate mailbox writes (7FEh/7FFh) to opposite port. |
| BUSYL, BUSYR | BUSY inputs | Active-low write-inhibit signals - must be driven externally (e.g., by MASTER's BUSY outputs); no internal generation. |
| VCC, GND | Power & ground | Multiple VCC/GND pins distributed for noise reduction; all must be connected per datasheet Note 1 & 2. |
Key Features
| Feature | Design Value |
|---|---|
| SLAVE-only BUSY interface | Accepts external BUSY signal to disable writes - eliminates need for discrete arbitration logic in width-expanded arrays. |
| 2 V data retention | Maintains memory contents with ≤100 µA ICCDR at 2 V supply - enables seamless switchover to backup battery during main power loss. |
| Dual interrupt mailboxes | Hardware-triggered INTL/INTR flags via dedicated 7FEh/7FFh addresses - reduces software polling and ISR latency. |
| Asynchronous dual-port operation | Independent left/right control, address, and data buses - allows concurrent read/write to different addresses with zero wait states. |
| Low-power standby modes | ISB3 = 5 µA (both ports fully disabled), ISB4 = 115 µA (one port active) - optimizes energy use in burst-traffic systems. |
Applications
| Industrial PLC Communication Module | Avionics Data Logger |
|---|---|
|
Use Scenario: Two microcontrollers exchange status and command packets via shared memory in a safety-critical motion control loop. IC Role / Device Role / Timing Role: SLAVE dual-port SRAM providing atomic mailbox access with hardware interrupt signaling and BUSY-controlled write arbitration. Use Value: Eliminates software semaphores and race conditions; 20 ns access ensures sub-µs interprocessor response time. |
Use Scenario: Flight data recorder buffers sensor streams from multiple ADCs while simultaneously allowing ground-station readout during maintenance. IC Role / Device Role / Timing Role: Dual-port SRAM acting as real-time capture buffer (left port) and host-access buffer (right port) with independent control. Use Value: Enables continuous logging without halting acquisition - no data loss during host read cycles due to full port independence. |
| Medical Imaging Control Board | Telecom Line Card Buffer |
|
Use Scenario: FPGA-based image processor writes reconstructed frames into shared memory while ARM host reads and compresses them for network upload. IC Role / Device Role / Timing Role: SLAVE SRAM in MASTER/SLAVE pair (with IDT71321) handling 16-bit+ data width expansion with centralized BUSY arbitration. Use Value: Scales memory bandwidth to 16-bit without adding delay or complexity - BUSY propagation preserves data coherency across width-expanded banks. |
Use Scenario: Packet buffering between line-interface ASIC and traffic management CPU in carrier-grade Ethernet switch. IC Role / Device Role / Timing Role: Dual-port SRAM serving as zero-latency packet FIFO with interrupt-driven threshold signaling (7FEh/7FFh mailboxes). Use Value: Reduces CPU polling overhead by >90%; hardware interrupts trigger DMA transfers only when buffers reach defined occupancy levels. |
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-20AXC | 2K × 16 configuration; 20 ns access; built-in arbitration logic; no BUSY input - uses SEM/FLAG pins instead. | Requires redesign of arbitration interface; supports wider data paths natively but lacks SLAVE-specific BUSY input behavior. | Select if migrating to 16-bit native bus or requiring integrated arbitration - not drop-in for IDT71421 SLAVE topology. |
| IDT71321LA20JG8 | MASTER counterpart: includes BUSY output, on-chip arbitration, and INT flag generation - not interchangeable as SLAVE. | Cannot replace 71421LA20JG8 in SLAVE position; used only as MASTER in paired configurations. | Required when building MASTER/SLAVE array - must be paired with 71421LA20JG8, not substituted for it. |
Compared with CY7C024AV-20AXC and IDT71321LA20JG8, the 71421LA20JG8 uniquely provides a dedicated SLAVE interface with BUSY-as-input semantics and fixed interrupt mailboxes - essential for maintaining timing integrity and minimizing external logic in legacy IDT-based dual-processor systems.
Availability
71421LA20JG8 is available at Aetrix Electronics and suitable for industrial PLC communication modules, avionics data loggers, and medical imaging control boards requiring stable component supply, long-lifecycle support, and guaranteed industrial-temperature performance.
Supply support for 71421LA20JG8 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, specialized in high-performance memory, timing, and interface ICs for communications, computing, and industrial markets.
The IDT71421 product line was designed specifically for MASTER/SLAVE dual-port SRAM expansion in real-time embedded systems - prioritizing deterministic arbitration, low-latency interprocessor messaging, and battery-backed reliability.
FAQ
What is the function of BUSY pins on the 71421LA20JG8?
The BUSY pins (BUSYL and BUSYR) on the 71421LA20JG8 are inputs - not outputs - and serve as active-low write-inhibit signals. When asserted low by an external MASTER device (e.g., IDT71321), they block writes to the corresponding port regardless of R/W or CE state. This behavior is fundamental to its SLAVE role and differs from MASTER devices that drive BUSY.
Does the 71421LA20JG8 support battery backup operation?
Yes, the 71421LA20JG8 supports battery backup: at VCC = 2.0 V, it retains data with ICCDR ≤ 100 µA (typical) and guarantees operation down to –40°C. This capability is exclusive to LA-grade parts and requires CE and all inputs held at valid CMOS levels (VCC − 0.2 V or GND) during retention mode.
How do the interrupt mailboxes work on the 71421LA20JG8?
The 71421LA20JG8 uses fixed addresses 7FEh and 7FFh as hardware interrupt mailboxes. A write to 7FEh by the right port asserts INTL; a write to 7FFh by the left port asserts INTR. Clearing requires reading the same address with OE and CE active - no software register writes needed. This offloads synchronization logic from the host processors.
Can the 71421LA20JG8 operate as a standalone dual-port RAM without a MASTER?
Yes - the 71421LA20JG8 functions as a fully independent dual-port SRAM without a MASTER. However, BUSY arbitration is disabled (BUSY inputs must be tied high), and interrupt flags remain operational. It loses only the hardware write-inhibit feature; all memory, timing, and power specifications remain valid in standalone mode.
What package does the 71421LA20JG8 use, and are pinouts compatible with other IDT dual-port SRAMs?
The 71421LA20JG8 uses a 64-pin TQFP (JG8) package matching the PNG64/PPG64 footprint. Its pinout is identical to other 64-pin IDT71421 variants (e.g., 71421SA25JG8) and shares functional pin alignment with IDT71321 in the same package - though BUSY pin roles differ (input vs. output). Mechanical and solder-reflow profiles are fully compatible.
71421LA20JG8 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:
- 20ns
- Access Time:
- 20 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 52-PLCC (19.13x19.13)
71421LA20JG8 FAQ
1.How can I place an order for 71421LA20JG8 through Aetrix?
Please submit a Request for Quotation (RFQ) for 71421LA20JG8 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 71421LA20JG8 reliable?
The price and inventory of 71421LA20JG8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71421LA20JG8 is usually 5 days.
3.What payment methods are accepted for 71421LA20JG8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71421LA20JG8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71421LA20JG8?
71421LA20JG8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71421LA20JG8 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 71421LA20JG8?
For technical support, including 71421LA20JG8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71421LA20JG8 requirements.
6.How does Aetrix verify that 71421LA20JG8 is sourced from the original manufacturer or authorized distributors?
All 71421LA20JG8 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 71421LA20JG8 meets industry standards.
7.What is the process for return or replacement of 71421LA20JG8?
All 71421LA20JG8 units undergo pre-shipment inspection (PSI). If there is an issue with 71421LA20JG8, 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 71421LA20JG8 part is unused and in its original packaging.
Return procedure for 71421LA20JG8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
71421LA20JG8 Tags
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AT24C02C-XHM-T
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