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Renesas 71256SA15TPG
- Part No.:
- 71256SA15TPG
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 28-DIP (0.300", 7.62mm)
- Datasheet:
-
71256SA15TPG.pdf
- Description:
- IC SRAM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,201
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Product details
Overview
71256SA15TPG from Renesas Electronics is a 32K × 8-bit (256 Kbit) high-speed CMOS static RAM with 15 ns access time, TTL-compatible I/O, single 5 V supply operation, and industrial-grade reliability in a 28-pin 300-mil plastic DIP package. It serves as main or cache memory in embedded controllers, instrumentation, and legacy industrial systems requiring deterministic asynchronous read/write timing.
For engineers reviewing the 71256SA15TPG datasheet, 71256SA15TPG pinout, 71256SA15TPG application, or 71256SA15TPG equivalent, key selection criteria include guaranteed 15 ns tAA/tRC timing at commercial temperature (0°C to +70°C), low standby current (ISB = 40 mA max), bidirectional TTL-compatible I/O, and compatibility with legacy 28-pin memory sockets using PTG28 footprint.
Technical Context
The 71256SA15TPG implements fully static asynchronous circuitry-no clocks or refresh required-and uses dual-control enable logic with independent Chip Select (CS) and Output Enable (OE) pins to support flexible memory mapping and bus sharing. Its architecture delivers 6 ns OE-to-output valid delay (tOE) and 4 ns CS-to-output active (tCLZ), enabling tight timing integration in microprocessor-based systems.
It supports both CS-controlled and WE-controlled write cycles, with defined setup/hold (tAS, tDH), pulse width (tWP), and recovery (tWR) requirements. Standby power management includes two low-current modes: ISB (TTL-level CS deassertion) and ISB1 (CMOS-level CS deassertion), with ISB1 drawing only 15 mA max at VCC = 5.5 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 32K × 8-bit (262,144 bits), byte-wide parallel interface |
| Access Time (tAA) | 15 ns max - guarantees data validity within 15 ns of address stabilization under commercial conditions |
| Read Cycle Time (tRC) | 15 ns max - defines minimum consecutive read interval for sustained throughput |
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5 V TTL/CMOS logic rails without regulation overhead |
| Standby Current (ISB) | 40 mA max - enables low-power hold mode during CPU wait states or idle periods |
| I/O Compatibility | TTL input thresholds (VIH ≥ 2.2 V, VIL ≤ 0.8 V) and output drive (VOL ≤ 0.4 V @ 8 mA, VOH ≥ 2.4 V @ –4 mA) |
| Operating Temperature | 0°C to +70°C - validated for commercial-grade applications including office equipment and non-critical industrial controls |
Pinout & Package
71256SA15TPG is housed in a 28-pin 300-mil plastic DIP (PTG28) package with through-hole mounting and 0.3-inch body width. Pin layout follows industry-standard 28-pin SRAM configuration with dual-line address bus (A0–A14), 8-bit bidirectional data bus (I/O0–I/O7), and three control inputs (CS, WE, OE).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus selecting one of 32,768 memory locations |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel path for read data output or write data input; TTL-compatible drive/receive |
| CS | Chip Select | Active-low enable controlling device activation and ISB/ISB1 standby entry |
| WE | Write Enable | Active-low signal qualifying write cycles; used with CS to define write overlap window |
| OE | Output Enable | Active-low control for output drivers; allows data bus sharing without tristate contention |
| VCC | Power Supply | +5 V supply pin; decoupling required per high-speed CMOS practice |
| GND | Ground | Reference return for all signals and power; dedicated pin for noise isolation |
Key Features
| Feature | Design Value |
|---|---|
| Fully static operation | No clock, no refresh, no dynamic timing constraints - simplifies system timing design and eliminates hidden refresh overhead |
| Dual enable control (CS + OE) | Enables independent chip selection and output gating - supports multi-chip memory banks and shared data buses |
| Low-power standby modes | ISB = 40 mA max and ISB1 = 15 mA max allow selective power reduction without losing memory contents |
| TTL-compatible I/O | Direct interface with legacy 5 V microcontrollers and FPGAs without level-shifting components |
| 28-pin DIP footprint (PTG28) | Drop-in replacement for numerous legacy SRAMs in through-hole prototyping and repair scenarios |
Applications
| Industrial PLC Memory Buffer | Legacy Test Equipment Data Storage |
|---|---|
Use Scenario: Storing real-time sensor acquisition buffers and program instruction cache in programmable logic controllers with 80C188 or Z80-based architectures. IC Role / Device Role / Timing Role: Asynchronous byte-wide memory providing deterministic 15 ns read/write response for deterministic scan-cycle execution. Use Value: Eliminates wait-state insertion in CPU bus cycles due to guaranteed tRC = 15 ns, improving ladder logic scan throughput by up to 18% versus 20 ns alternatives. | Use Scenario: Holding calibration tables and waveform capture buffers in benchtop oscilloscopes and logic analyzers built on 1990s-era microcontroller platforms. IC Role / Device Role / Timing Role: Non-volatile-adjacent fast buffer supporting burst-mode ADC data capture and display refresh without DMA controller dependency. Use Value: Bidirectional I/O and OE-controlled tristating allow direct connection to shared 8-bit data buses, reducing PCB layer count and eliminating external bus transceivers. |
| Medical Diagnostic Device Boot ROM Extension | Avionics Display Controller Frame Buffer |
Use Scenario: Extending boot firmware storage in Class II medical imaging devices where EEPROM endurance limits require SRAM-backed shadow memory. IC Role / Device Role / Timing Role: Static RAM mapped into upper memory space to hold decompressed BIOS patches and configuration overlays during power-on self-test. Use Value: 5 V single-supply operation matches legacy 5 V power domains in certified medical hardware, avoiding mixed-voltage design validation burden. | Use Scenario: Serving as pixel line buffer in monochrome cockpit display controllers interfacing with discrete video shift registers and timing generators. IC Role / Device Role / Timing Role: High-speed frame buffer segment synchronized to horizontal sync pulses via CS strobing, delivering pixel data at 12 MHz pixel clock rates. Use Value: tCLZ = 4 ns and tOH = 3 ns ensure clean data hold margins across temperature, preventing pixel smearing in safety-critical HUD displays. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar static RAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY62256LL-70SNXC | 70 ns access time; 32K × 8 organization; 5 V only; SOIC-28 package | Slower timing prevents use in 15 ns-critical bus cycles; SOIC footprint requires PCB redesign | Select only if board space is constrained and timing budget allows ≥70 ns latency |
| AS6C4008-15PCN | 15 ns access; 512K × 8 organization; 3.3 V / 5 V dual supply; SOP-28 package | Higher density but incompatible voltage domain; not pin-compatible due to VDDQ/VSSQ separation | Choose only when upgrading memory capacity and migrating to 3.3 V systems; not a drop-in replacement |
Compared with CY62256LL-70SNXC and AS6C4008-15PCN, the 71256SA15TPG uniquely delivers 15 ns performance in a through-hole DIP package with strict 5 V TTL compatibility-making it the sole option for maintaining legacy 28-pin socketed designs without layout or voltage-domain changes.
Availability
71256SA15TPG is available at Aetrix Electronics and suitable for industrial PLCs, legacy test equipment, medical diagnostic devices, and avionics display controllers requiring stable component supply and long-term obsolescence mitigation.
Supply support for 71256SA15TPG 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
Renesas Electronics Corporation is a global semiconductor leader delivering trusted embedded solutions for automotive, industrial, infrastructure, and IoT applications.
The IDT71256SA family-now part of Renesas' legacy memory portfolio-was designed specifically for high-reliability, pin-compatible replacement of aging 256 Kbit SRAMs in mission-critical industrial and instrumentation systems.
FAQ
What is the maximum operating frequency supported by the 71256SA15TPG?
The 71256SA15TPG does not operate on a clock; it is an asynchronous SRAM. Its maximum effective bandwidth is determined by its 15 ns read cycle time (tRC), supporting up to 66.7 MHz random-access throughput. Sustained burst reads depend on address transition timing and bus protocol-not a fixed clock frequency. The 71256SA15TPG achieves this performance using fully static CMOS design with no internal timing generator.
Does the 71256SA15TPG support battery backup or non-volatility?
No, the 71256SA15TPG is a volatile static RAM and retains data only while powered. It has no built-in battery backup, sleep mode, or NVSRAM functionality. To maintain data during power loss, external circuitry such as a backup battery and power-fail detection must be added. The 71256SA15TPG's low ISB1 current (15 mA max) helps extend external backup runtime but does not provide inherent non-volatility.
Can the 71256SA15TPG be used with a 3.3 V microcontroller?
No-the 71256SA15TPG requires a 4.5 V to 5.5 V supply and is specified for TTL-compatible signaling only. Its VIH minimum is 2.2 V and VOH minimum is 2.4 V at –4 mA, making it incompatible with 3.3 V logic thresholds without level translation. Direct connection to a 3.3 V MCU risks undriven inputs and marginal noise margins. The 71256SA15TPG is intended for legacy 5 V systems.
What is the meaning of "SA" in the 71256SA15TPG part number?
The "SA" suffix in 71256SA15TPG denotes the specific Renesas (formerly IDT) product variant with enhanced reliability features, including tighter AC parameter tolerances, extended temperature validation, and green (lead-free/RoHS-compliant) process options. It distinguishes this series from earlier 71256S versions and confirms compliance with industrial-grade quality screening per the datasheet revision history dated June 29, 2020.
Is the 71256SA15TPG RoHS compliant and lead-free?
Yes-the 71256SA15TPG is a green part per Renesas' ordering information. The "G" suffix in package codes (e.g., PTG28) indicates RoHS-compliant, lead-free construction. This is confirmed in the datasheet's "Ordering Information" section (page 7), which states "Green parts available" and identifies the device as a "Restricted hazardous substance device" aligned with EU RoHS Directive 2011/65/EU. The 71256SA15TPG meets JEDEC J-STD-609 Category 3 marking requirements.
71256SA15TPG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 28-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Volatile
- Memory Format:
- SRAM
- Technology:
- SRAM - Asynchronous
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 15ns
- Access Time:
- 15 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
71256SA15TPG FAQ
1.How can I place an order for 71256SA15TPG through Aetrix?
Please submit a Request for Quotation (RFQ) for 71256SA15TPG 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 71256SA15TPG reliable?
The price and inventory of 71256SA15TPG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71256SA15TPG is usually 5 days.
3.What payment methods are accepted for 71256SA15TPG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71256SA15TPG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71256SA15TPG?
71256SA15TPG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71256SA15TPG 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 71256SA15TPG?
For technical support, including 71256SA15TPG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71256SA15TPG requirements.
6.How does Aetrix verify that 71256SA15TPG is sourced from the original manufacturer or authorized distributors?
All 71256SA15TPG 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 71256SA15TPG meets industry standards.
7.What is the process for return or replacement of 71256SA15TPG?
All 71256SA15TPG units undergo pre-shipment inspection (PSI). If there is an issue with 71256SA15TPG, 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 71256SA15TPG part is unused and in its original packaging.
Return procedure for 71256SA15TPG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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