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Renesas 71421SA25PF8
- Part No.:
- 71421SA25PF8
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 64-LQFP
- Datasheet:
-
71421SA25PF8.pdf
- Description:
- IC SRAM 16KBIT PARALLEL 64TQFP
- Quantity:
- Payment:
- Shipping:
Inventory:3,148
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Product details
Overview
71421SA25PF8 from IDT (now Renesas) is a 2K × 8 dual-port static RAM configured as a SLAVE device in MASTER/SLAVE memory expansion systems, supporting fully asynchronous port-to-port communication with BUSY input and interrupt flag (INTR) functionality. It delivers 25 ns max read cycle time, operates on single 5V ±10% supply, and supports industrial temperature range (–40°C to +85°C). It is used in real-time interprocessor communication buffers where deterministic arbitration and low-latency data exchange are required.
For engineers reviewing the 71421SA25PF8 datasheet, 71421SA25PF8 pinout, 71421SA25PF8 application, or 71421SA25PF8 equivalent, key selection criteria include its role as a SLAVE dual-port SRAM with BUSY input (not output), interrupt reset via address 7FFH, 64-pin TQFP package, and compatibility only with IDT71321 MASTER devices in width-expanded systems.
Technical Context
The 71421SA25PF8 implements a dedicated SLAVE architecture: BUSY is an input (not output), enabling write-inhibit control from an external IDT71321 MASTER; it lacks on-chip arbitration logic and relies entirely on the MASTER for BUSY generation. Its interrupt logic responds to writes to address 7FFH (set INTR) and reads from 7FFH (clear INTR), with timing parameters tINS/tINR specified at ≤25 ns.
It supports two independent asynchronous ports (left/right), each with separate CE, OE, R/W, address (A0–A10), and I/O (I/O0–I/O7) signals. Power management includes TTL-level standby (ISB1 = 20 mA typ.) and full CMOS-level standby (ISB3 = 1.0 mA typ.), but excludes battery backup - that feature is exclusive to LA-grade variants.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 2K × 8 bits (2048 words × 8-bit wide), no internal parity or ECC |
| Max Read Cycle Time | 25 ns - defines minimum time between successive read accesses on same port |
| Supply Voltage | 5.0 V ±10% - requires single-rail 4.5–5.5 V supply; not compatible with 3.3 V or mixed-voltage operation |
| Operating Temperature | –40°C to +85°C - qualified for industrial environments without derating |
| Standby Current (ISB1) | 20 mA typical - active-port disabled, TTL-level inputs, both CEs high |
| Interrupt Set/Reset Time | tINS/tINR ≤25 ns - guarantees interrupt assertion/clearing within one 25 ns cycle after valid address access |
| BUSY Input Timing (tWB) | 0 ns min - BUSY assertion on slave takes effect immediately upon MASTER's BUSY output transition |
Pinout & Package
71421SA25PF8 is housed in a 64-pin TQFP (PNG64) package, 14 mm × 14 mm × 1.4 mm body, lead-free and RoHS-compliant. Pin 1 is marked by a dot; all VCC pins (e.g., pins 33, 47, 48, 63, 64) must be decoupled locally; all GND pins (e.g., pins 32, 46, 62) require low-impedance ground plane connection.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0R–A10R | Right-port address inputs | 11-bit address bus for right port; A0R = LSB, A10R = MSB; latched on CE/R/W edge |
| I/O0R–I/O7R | Right-port bidirectional data | 8-bit data path; direction controlled by R/WR and OER; high-impedance when OER = VIH |
| CER | Right-port chip enable | Active-low; enables right-port access and powers up I/O/address circuitry when low |
| OER | Right-port output enable | Active-low; controls I/O drivers - outputs enabled only when CER = OER = VIL |
| R/WR | Right-port read/write control | Active-low write; when CER = VIL and R/WR = VIL → write; R/WR = VIH → read (if OER = VIL) |
| INTR | Right-port interrupt flag output | Open-drain output; requires external pull-up; asserted (low) when left port writes to 7FFH |
| BUSYR | Right-port BUSY input | Active-low input; when low, internally inhibits all right-port writes regardless of R/WR or CER state |
| VCC | Power supply | 5V ±10% supply; multiple pins (33,47,48,63,64) must be connected and decoupled |
| GND | Ground reference | System ground; multiple pins (32,46,62) require low-inductance connection to PCB ground plane |
Key Features
| Feature | Design Value |
|---|---|
| SLAVE-only BUSY interface | BUSYR is input-only - eliminates need for external arbitration logic when paired with IDT71321 MASTER |
| Dedicated interrupt mailbox | Address 7FFH serves as hardware-managed interrupt register: write sets INTR, read clears INTR |
| Asynchronous dual-port operation | Left and right ports operate independently - no clock required; no synchronization latency between ports |
| Industrial-grade reliability | Qualified from –40°C to +85°C with full DC/AC specs guaranteed across temperature and voltage |
| Low-power standby modes | ISB1 = 20 mA typ. (TTL inputs), ISB3 = 1.0 mA typ. (CMOS inputs) - reduces system power during idle cycles |
Applications
| Real-Time Interprocessor Communication | Redundant Control System Buffering |
|---|---|
Use Scenario: Two microcontrollers exchange status and command data via shared memory without software polling or OS intervention. IC Role / Device Role / Timing Role: 71421SA25PF8 acts as SLAVE buffer in MASTER/SLAVE pair; receives writes from MASTER (IDT71321), asserts INTR to notify local CPU of new data. Use Value: Eliminates race conditions via hardware BUSY arbitration and provides sub-25 ns interrupt latency for deterministic response. |
Use Scenario: Primary and backup controllers maintain synchronized state using mirrored memory regions; conflict resolution occurs at hardware level. IC Role / Device Role / Timing Role: 71421SA25PF8 serves as SLAVE in dual-MASTER configuration (with external OR logic), accepting updates from either controller while blocking concurrent writes via BUSYR. Use Value: Prevents memory corruption during failover by enforcing atomic write access - no firmware coordination needed. |
| Industrial PLC Dual-Core Data Exchange | Avionics Sensor Fusion Interface |
Use Scenario: Safety-critical PLC uses separate cores for motion control and I/O scanning; shared variables updated via dual-port RAM. IC Role / Device Role / Timing Role: 71421SA25PF8 deployed as SLAVE on I/O-scanning core side; MASTER (IDT71321) resides on motion-control core, driving BUSYR to block writes during critical scan windows. Use Value: Guarantees data consistency without disabling interrupts or adding software locks - meets IEC 61508 SIL-3 timing constraints. |
Use Scenario: Flight control computer fuses inertial and GPS data streams; sensor processors write raw data to shared memory for fusion algorithm execution. IC Role / Device Role / Timing Role: 71421SA25PF8 functions as SLAVE buffer for GPS processor port; INTR triggers fusion CPU upon new epoch data arrival at 7FFH. Use Value: Enables zero-overhead, lock-free data handoff with <25 ns interrupt propagation - critical for 100 Hz closed-loop control. |
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-25AXC | 32K × 16 organization, 25 ns access, integrated BUSY arbitration, no MASTER/SLAVE dependency | Standalone dual-port; no external MASTER required; larger memory but higher pin count (100-pin TQFP) | Select when full arbitration logic and larger capacity are needed - avoids MASTER/SLAVE pairing complexity |
| IDT71321SA25PF8 | 2K × 8 MASTER device; provides BUSY output, INTL flag, on-chip arbitration; pin-compatible in same 64-pin TQFP | Must be used as MASTER with 71421SA25PF8 SLAVE; cannot operate standalone in SLAVE role | Select only when building width-expanded systems requiring hardware-controlled BUSY distribution across multiple SLAVE devices |
Compared with CY7C024AV-25AXC and IDT71321SA25PF8, the 71421SA25PF8 offers minimal footprint and deterministic latency in constrained MASTER/SLAVE topologies, but lacks autonomy - it cannot arbitrate or generate interrupts without its MASTER counterpart.
Availability
71421SA25PF8 is available at Aetrix Electronics and suitable for real-time interprocessor communication, industrial PLC data exchange, avionics sensor fusion, and redundant control system buffering requiring stable component supply across extended production lifecycles.
Supply support for 71421SA25PF8 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 high-performance data movement ICs.
The IDT71321/71421 family was designed specifically for deterministic, low-latency interprocessor communication in hard real-time embedded systems - emphasizing hardware arbitration, interrupt signaling, and seamless width expansion without external logic.
FAQ
Is 71421SA25PF8 a standalone dual-port RAM or does it require a companion device?
71421SA25PF8 is a SLAVE-only device and requires an IDT71321 MASTER (e.g., IDT71321SA25PF8) to function in a complete dual-port system. It has no on-chip arbitration logic and relies on BUSYR input for write inhibition - it cannot operate autonomously as a full dual-port RAM.
What is the function of the BUSYR pin on 71421SA25PF8?
BUSYR is an active-low input pin on 71421SA25PF8. When driven low by an external IDT71321 MASTER, it internally blocks all write operations to the right port - regardless of R/WR or CER state - ensuring conflict-free access during address contention.
How is the INTR interrupt flag cleared on 71421SA25PF8?
The INTR flag on 71421SA25PF8 is cleared by reading from memory address 7FFH (hex) on the right port: CER = OER = VIL, R/WR = VIH, and A0R–A10R = 7FFH. This read access resets the flag synchronously with the access cycle - no separate control register is involved.
Does 71421SA25PF8 support battery backup or low-voltage data retention?
No. 71421SA25PF8 is an SA-grade (standard power) device and does not support battery backup. Data retention at 2V is exclusive to LA-grade variants (e.g., 71421LA25PF8). The 71421SA25PF8 requires continuous 4.5–5.5 V supply for operation and data retention.
Can 71421SA25PF8 be used without an IDT71321 MASTER in a single-processor system?
No. Because 71421SA25PF8 lacks internal arbitration and has BUSYR as input-only, it cannot manage port conflicts or generate BUSY signals. In a single-processor system, a self-contained dual-port RAM like CY7C024AV-25AXC would be appropriate - 71421SA25PF8 is architecturally dependent on the MASTER.
71421SA25PF8 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 64-LQFP
- 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:
- 25ns
- Access Time:
- 25 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)
71421SA25PF8 FAQ
1.How can I place an order for 71421SA25PF8 through Aetrix?
Please submit a Request for Quotation (RFQ) for 71421SA25PF8 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 71421SA25PF8 reliable?
The price and inventory of 71421SA25PF8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71421SA25PF8 is usually 5 days.
3.What payment methods are accepted for 71421SA25PF8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71421SA25PF8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71421SA25PF8?
71421SA25PF8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71421SA25PF8 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 71421SA25PF8?
For technical support, including 71421SA25PF8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71421SA25PF8 requirements.
6.How does Aetrix verify that 71421SA25PF8 is sourced from the original manufacturer or authorized distributors?
All 71421SA25PF8 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 71421SA25PF8 meets industry standards.
7.What is the process for return or replacement of 71421SA25PF8?
All 71421SA25PF8 units undergo pre-shipment inspection (PSI). If there is an issue with 71421SA25PF8, 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 71421SA25PF8 part is unused and in its original packaging.
Return procedure for 71421SA25PF8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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