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Renesas 71421LA55PF
- Part No.:
- 71421LA55PF
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 64-LQFP
- Datasheet:
-
71421LA55PF.pdf
- Description:
- IC SRAM 16KBIT PARALLEL 64TQFP
- Quantity:
- Payment:
- Shipping:
Inventory:3,604
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Product details
Overview
71421LA55PF from Integrated Device Technology is a low-power 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, 2 V data retention, and industrial temperature range (–40°C to +85°C) - used in real-time interprocessor messaging and shared-memory arbitration.
For engineers reviewing the 71421LA55PF datasheet, 71421LA55PF pinout, 71421LA55PF application, or 71421LA55PF equivalent, key selection criteria include its SLAVE-only BUSY input behavior, battery-backed 2 V data retention capability, 64-pin TQFP package, TTL-compatible 5 V ±10% supply, and interrupt mailbox addressing at 7FEH/7FFH.
Technical Context
The 71421LA55PF implements dedicated SLAVE-side arbitration logic: BUSYR and BUSYL are inputs (not outputs), internally inhibiting writes when asserted low; it lacks on-chip port arbitration - that function resides solely in the MASTER IDT71321. Its interrupt generation is strictly address-triggered: writing to 7FFH sets INTR, reading 7FFH clears it; writing to 7FEH sets INTL, reading 7FEH clears it.
This device operates fully asynchronously per port, with independent CE, R/W, and OE controls for left (L) and right (R) ports. It supports two distinct power states: active mode (typ. 325 mW) and full standby (typ. 1 µA at 2 V), enabled by CMOS-level CE control and compatible with battery backup operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 2K × 8 (2048 words × 8 bits), dual-port SRAM with separate L/R address/data/control paths |
| Max Read Cycle Time | 55 ns - defines minimum time between successive reads on same port |
| Data Retention Voltage | 2.0 V - enables battery backup operation without external regulators |
| Operating Temperature | –40°C to +85°C - qualified for industrial environments without derating |
| Supply Voltage | 4.5 V to 5.5 V - TTL-compatible single 5 V ±10% rail, no auxiliary supplies required |
| Standby Current (Full) | 1 µA typ. at 2 V - enables ultra-low-power retention during system sleep |
| Interrupt Address Map | INTL triggered by write to 7FEH; INTR triggered by write to 7FFH - fixed mailbox locations |
Pinout & Package
71421LA55PF is housed in a 64-pin TQFP (PNG64) package with 0.5 mm pitch, 14 mm × 14 mm body, and exposed thermal pad. Pin functions are symmetric for left/right ports, with dedicated BUSY inputs and interrupt outputs.
| 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; 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 (L/R) | Active-low enables respective port; controls power-down entry/exit |
| R/WL / R/WR | Read/write direction (L/R) | Low = write, High = read; determines data flow direction per port |
| OEL / OER | Output enable (L/R) | Active-low enables I/O drivers; independent of CE for output gating |
| BUSYL / BUSYR | BUSY input (L/R) | SLAVE-only: low = write inhibit; driven externally by MASTER's BUSY output |
| INTL / INTR | Interrupt flag output (L/R) | Open-drain outputs; require pull-up; indicate mailbox activity (7FEH/7FFH) |
| VCC / GND | Power supply pins | Multiple VCC/GND pairs ensure stable core voltage and low-noise grounding |
Key Features
| Feature | Design Value |
|---|---|
| SLAVE-specific BUSY interface | BUSY pins are inputs only - eliminates need for external arbitration logic in width-expanded arrays |
| Fixed interrupt mailboxes | Hardware-interrupt generation at immutable addresses 7FEH (INTL) and 7FFH (INTR) - no register programming required |
| 2 V data retention | Maintains memory contents during main power loss using coin-cell or supercap backup - no volatile refresh needed |
| Asynchronous dual-port operation | Independent L/R control allows concurrent read/write to different addresses - no clock synchronization overhead |
| TTL-compatible signaling | Direct interface with legacy 5 V microcontrollers and FPGAs without level-shifting circuitry |
Applications
| Real-Time Interprocessor Messaging | Dual-CPU Shared Memory Buffer |
|---|---|
Use Scenario: Two independent CPUs exchange status, commands, and telemetry via shared memory without OS intervention or polling loops. IC Role / Device Role / Timing Role: SLAVE dual-port RAM provides non-blocking, hardware-synchronized message passing using INTL/INTR flags and BUSY-controlled write arbitration. Use Value: Eliminates software mutexes and reduces inter-CPU latency to sub-60 ns - critical for deterministic response in motion control systems. |
Use Scenario: A host processor offloads real-time signal processing to a dedicated DSP, sharing sensor buffers and result queues. IC Role / Device Role / Timing Role: 71421LA55PF acts as SLAVE in a MASTER/SLAVE pair, enabling 16-bit+ word width expansion while preserving atomicity across ports. Use Value: Enables full-speed parallel access to shared buffers without wait states or external glue logic - maintains throughput at 18.2 MB/s (55 ns cycle). |
| Industrial PLC Data Exchange | Battery-Backed Configuration Storage |
Use Scenario: Programmable Logic Controller modules coordinate I/O scan cycles and ladder logic execution across redundant CPU units. IC Role / Device Role / Timing Role: SLAVE device synchronizes state snapshots between master and slave controllers using BUSY-driven write blocking and interrupt-driven notification. Use Value: Guarantees coherent memory updates during hot-swapping or failover - prevents partial writes and race conditions in safety-critical sequences. |
Use Scenario: Embedded controller retains calibration tables, network settings, and fault logs during AC power loss or brownout events. IC Role / Device Role / Timing Role: 71421LA55PF operates in data retention mode at 2 V, drawing ≤1.5 mA from backup source while preserving all 2048×8 bits. Use Value: Extends backup runtime beyond 100 hours using standard CR2032 cells - avoids EEPROM wear-out and write-latency 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 |
|---|---|---|---|
| CY7C1371DV33-167BZI | 3.3 V core, 167 MHz QDR interface, no BUSY arbitration logic | Requires external arbitration for multi-processor access; no 2 V retention | Select when migrating to 3.3 V systems with high-bandwidth streaming needs, not for legacy 5 V interprocessor messaging. |
| IDT71321LA55PF | MASTER variant with on-chip arbitration, BUSY outputs, and identical timing/package | Enables standalone use or MASTER role in width expansion; cannot operate as SLAVE | Choose when building a single-device dual-port system or acting as BUSY source - not interchangeable with 71421LA55PF in SLAVE position. |
Compared with CY7C1371DV33-167BZI and IDT71321LA55PF, the 71421LA55PF uniquely delivers SLAVE-specific BUSY input behavior and 2 V data retention in a 5 V TTL system - making it irreplaceable in industrial interprocessor designs requiring hardware-enforced write coherency and battery backup.
Availability
71421LA55PF is available at Aetrix Electronics and suitable for industrial PLCs, dual-CPU embedded controllers, and real-time motion control systems requiring stable component supply, long-term lifecycle support, and guaranteed 55 ns timing performance.
Supply support for 71421LA55PF 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, and RF power solutions for communications and industrial markets.
The IDT71421 family was designed specifically for hardware-synchronized interprocessor communication in deterministic embedded systems - emphasizing low-latency arbitration, interrupt-driven messaging, and robust data retention under power interruption.
FAQ
Is 71421LA55PF a MASTER or SLAVE dual-port RAM?
The 71421LA55PF is exclusively a SLAVE device. It accepts BUSY signals as inputs (BUSYL/BUSYR) to inhibit writes, lacks on-chip arbitration logic, and relies on an external IDT71321 MASTER to generate BUSY outputs. Using 71421LA55PF as a MASTER will result in non-functional BUSY and arbitration behavior.
What are the exact interrupt mailbox addresses for 71421LA55PF?
The 71421LA55PF uses fixed interrupt mailbox addresses: writing to address 7FEH (hex) asserts the INTL flag, and writing to 7FFH (hex) asserts the INTR flag. Clearing is performed by reading those same addresses - no configuration registers or software initialization is required for interrupt functionality in 71421LA55PF.
Does 71421LA55PF support battery backup operation?
Yes, 71421LA55PF supports true battery backup: it retains valid data at VCC = 2.0 V with typical current draw of 100 µA (max 1500 µA commercial, 4000 µA industrial). This is a hardware feature of the LA suffix version - SA variants do not provide 2 V retention, and the 71421LA55PF must be operated within its specified 2 V retention window to guarantee data integrity.
Can 71421LA55PF operate independently without a MASTER device?
No - 71421LA55PF requires an external MASTER (e.g., IDT71321) to drive its BUSY inputs for correct arbitration. Without BUSY assertion, concurrent writes to the same address from both ports may cause data corruption. The 71421LA55PF has no internal mechanism to resolve contention; it depends entirely on the MASTER's BUSY output to enforce write ordering.
What package type is used for 71421LA55PF?
The 71421LA55PF is supplied in a 64-pin TQFP package (PNG64), measuring 14 mm × 14 mm × 1.4 mm with 0.5 mm lead pitch and an exposed thermal pad. This package is RoHS-compliant, green-certified, and compatible with standard reflow soldering profiles - distinct from the 52-pin PLCC or STQFP variants offered in the same family.
71421LA55PF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 64-LQFP
- Packaging:
- Tray
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 64-TQFP (14x14)
71421LA55PF FAQ
1.How can I place an order for 71421LA55PF through Aetrix?
Please submit a Request for Quotation (RFQ) for 71421LA55PF 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 71421LA55PF reliable?
The price and inventory of 71421LA55PF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71421LA55PF is usually 5 days.
3.What payment methods are accepted for 71421LA55PF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71421LA55PF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71421LA55PF?
71421LA55PF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71421LA55PF 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 71421LA55PF?
For technical support, including 71421LA55PF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71421LA55PF requirements.
6.How does Aetrix verify that 71421LA55PF is sourced from the original manufacturer or authorized distributors?
All 71421LA55PF 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 71421LA55PF meets industry standards.
7.What is the process for return or replacement of 71421LA55PF?
All 71421LA55PF units undergo pre-shipment inspection (PSI). If there is an issue with 71421LA55PF, 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 71421LA55PF part is unused and in its original packaging.
Return procedure for 71421LA55PF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
71421LA55PF Tags
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