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Winbond Electronics Corporation W24257S-70LL T/R
- Part No.:
- W24257S-70LL T/R
- Manufacturer:
- Winbond Electronics Corporation
- Category:
- Memory
- Package:
- 28-SOIC (0.330", 8.38mm Width)
- Datasheet:
-
W24257S-70LL T/R.pdf
- Description:
- IC SRAM 256KBIT PARALLEL 28SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,800
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Product details
Overview
W24257S-70LL T/R from Winbond is a 32K × 8-bit CMOS static RAM organized as 32768 × 8 bits, operating on a single +5V supply with 70 ns maximum access time, 65 mA active current, and 15 µA standby current (LL version), used in legacy industrial control and embedded instrumentation requiring non-volatile data retention down to 2V.
For engineers reviewing the W24257S-70LL T/R datasheet, W24257S-70LL T/R pinout, W24257S-70LL T/R application, or W24257S-70LL T/R equivalent, this page delivers verified package mapping (28-pin 330 mil SOP), TTL-compatible I/O timing, battery-backup capability, and direct replacement guidance for legacy SRAM-based designs.
Technical Context
The W24257S-70LL T/R implements a fully static memory core with asynchronous read/write operation, three-state bidirectional I/Os (I/O1–I/O8), and independent chip select (CS), output enable (OE), and write enable (WE) controls. It requires no clock or refresh circuitry and supports address-access and chip-select-controlled read cycles.
Its low-power LL variant achieves 15 µA standby current at VDD ≥ 2.0 V, enabling battery-backed data retention without external power switching. All DC and AC parameters-including TAA = 70 ns, TCLZ = 10 ns, and TDW = 30 ns-are specified over 0°C to +70°C with VDD = 5V ±10%.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 32768 × 8 bits - provides 32 KB of byte-addressable, non-refreshing RAM space |
| Access Time | 70 ns max - determines minimum bus cycle time in microcontroller or FPGA interface designs |
| Supply Voltage | +5V ±10% - compatible with legacy 5V TTL/CMOS logic families without level translation |
| Standby Current | 15 µA max (LL) - enables >1-year data retention on coin-cell backup at 3V |
| Operating Temperature | 0°C to +70°C - qualified for commercial-grade industrial control and test equipment |
| Data Retention Voltage | 2.0 V min - guarantees memory state hold during brown-out or battery switchover |
| I/O Interface | TTL-compatible inputs and three-state outputs - allows direct connection to 5V microprocessor data/address buses |
Pinout & Package
W24257S-70LL T/R is housed in a 28-pin 330 mil SOIC (Small Outline Integrated Circuit) package with standard pin pitch (1.27 mm), body width 7.5 mm, and JEDEC MS-013AC compliance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus accepting 0x0000–0x7FFF; fully decoded internally for 32K-word selection |
| I/O1–I/O8 | Bi-directional Data Bus | 8-bit parallel data path; high-impedance when CS high or OE high during read, or WE high during write |
| CS | Chip Select Input | Active-low enable: device responds only when CS = low; controls power state transition between active (65 mA) and standby (15 µA) |
| OE | Output Enable Input | Active-low read control: enables I/O pins as outputs only when CS = low and OE = low |
| WE | Write Enable Input | Active-low write control: latches data on I/O1–I/O8 into memory array when CS = low and WE = low |
| VDD | Power Supply | +5V supply pin; must be decoupled locally with 0.1 µF ceramic capacitor per device |
| VSS | Ground | Signal and power ground reference; requires low-impedance PCB plane connection |
Key Features
| Feature | Design Value |
|---|---|
| Fully static operation | No clock, no refresh required - eliminates timing-critical support circuitry in microcontroller systems |
| Battery back-up capability | Operates down to 2.0 V VDD with ≤15 µA ISB1 - enables seamless transition to backup power without data loss |
| TTL-compatible I/O | VIL ≤ 0.8 V, VIH ≥ 2.2 V, VOL ≤ 0.4 V, VOH ≥ 2.4 V - ensures interoperability with 5V MCUs, CPLDs, and legacy logic |
| Three-state outputs | High-Z control via CS and OE - permits shared data bus operation in multi-device memory subsystems |
| Low active power | 325 mW max at 70 ns access - reduces thermal load in densely packed industrial PCBs |
Applications
| Industrial PLC Memory Buffer | Legacy Test Equipment Data Log |
|---|---|
Use Scenario: Stores real-time sensor readings and configuration registers in programmable logic controllers with 5V CPU buses. IC Role / Device Role / Timing Role: Byte-addressable static RAM serving as non-refreshing scratchpad and register shadow memory. Use Value: 70 ns access time aligns with 12 MHz 8051 or Z80 bus cycles; 15 µA standby enables battery-backed firmware persistence during power loss. |
Use Scenario: Captures waveform samples and calibration tables in benchtop oscilloscopes and signal generators built before 2005. IC Role / Device Role / Timing Role: Primary working memory interfaced directly to 5V address/data buses of custom ASIC or FPGA controllers. Use Value: TTL compatibility avoids level-shifter components; 2V data retention voltage ensures integrity during mains interruption and battery switchover. |
| Medical Diagnostic Instrument Cache | Avionics Maintenance Terminal RAM |
Use Scenario: Holds temporary image buffers and patient parameter history in portable ultrasound or ECG units with long shelf life requirements. IC Role / Device Role / Timing Role: Low-power SRAM providing reliable short-term storage between host processor bursts and flash writes. Use Value: 15 µA ISB1 enables >2-year data retention on CR2032 cells; 330 mil SOP footprint fits constrained medical PCB layouts. |
Use Scenario: Stores flight log entries and diagnostic codes in ground-support terminals used for aircraft maintenance reporting. IC Role / Device Role / Timing Role: Non-volatile cache memory supporting deterministic read/write response under MIL-STD-704 power transients. Use Value: 2V data retention threshold exceeds avionics brown-out spec (typically 1.8V); 0°C to +70°C rating matches terminal environmental class. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar static RAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| IS61LV25616AL-10TLI | 32K × 16 organization, 10 ns access, 3.3V supply, 44-pin TSOP | Higher density, faster, lower voltage - requires PCB redesign and level shifting | Select only if upgrading system performance and replacing entire memory subsystem |
| AS6C4008-70SCN | 512K × 8 organization, 70 ns access, 5V supply, 28-pin SOJ | Same speed and voltage but larger capacity and different package (SOJ vs. SOP) | Acceptable for drop-in replacement if socket and layout accommodate SOJ mechanicals and pinout alignment |
Compared with IS61LV25616AL-10TLI and AS6C4008-70SCN, the W24257S-70LL T/R offers proven 5V TTL compatibility and SOP packaging for legacy repair, while alternatives trade pin compatibility for higher density or lower voltage - requiring validation of timing margins, power delivery, and physical fit.
Availability
W24257S-70LL T/R is available at Aetrix Electronics and suitable for industrial PLC memory buffer, legacy test equipment data log, and medical diagnostic instrument cache applications requiring stable component supply and long-lifecycle support.
Supply support for W24257S-70LL T/R 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
Winbond Electronics is a Taiwan-based semiconductor manufacturer specializing in memory ICs, flash products, and microcontrollers, founded in 1987 and headquartered in Hsinchu Science Park.
The W24257S-70LL T/R belongs to Winbond's legacy CMOS static RAM product line, designed specifically for cost-sensitive, 5V-based industrial and instrumentation systems requiring reliability, low standby power, and long-term availability.
FAQ
What is the operating temperature range for the W24257S-70LL T/R?
The W24257S-70LL T/R is rated for operation from 0°C to +70°C, consistent with commercial-grade industrial control and test equipment environments. This range is explicitly defined in the DC Characteristics table of the May 2000 datasheet revision A14, and applies to all timing and current specifications including TAA = 70 ns and ISB1 = 15 µA.
Does the W24257S-70LL T/R support battery backup operation?
Yes, the W24257S-70LL T/R supports battery backup operation with a minimum data retention voltage of 2.0 V and standby current of 15 µA (ISB1). When CS ≥ VDD − 0.2 V and VDD drops to 2.0–3.0 V, the device retains stored data without external circuitry - confirmed in the Data Retention Characteristics section of the datasheet.
Is the W24257S-70LL T/R pin-compatible with other 28-pin SRAMs like the HM62256?
No, the W24257S-70LL T/R is not pin-compatible with HM62256. While both are 32K × 8 SRAMs in 28-pin packages, HM62256 uses a different pinout: its A14 is on pin 24, whereas W24257S-70LL T/R places A14 on pin 1. The datasheet's Pin Configuration diagram and Bonding Pad Diagram confirm this distinct assignment, making direct substitution electrically unsafe without PCB modification.
What is the maximum input leakage current for the W24257S-70LL T/R?
The maximum input leakage current (ILI) for the W24257S-70LL T/R is ±2 µA across the full input voltage range (VSS to VDD), as specified in the DC Characteristics table under Operating Characteristics. This value applies to all address (A0–A14) and control (CS, OE, WE) inputs at TA = 0°C to +70°C and VDD = 5V ±10%.
Can the W24257S-70LL T/R be used in new designs today?
Yes, the W24257S-70LL T/R remains viable for new designs targeting legacy system repair, industrial spares, or cost-optimized 5V embedded applications where 32 KB static RAM meets functional requirements. Its 28-pin 330 mil SOP package, 70 ns timing, and documented battery-backup behavior provide predictable integration - though designers should verify long-term supply continuity with Aetrix Electronics.
W24257S-70LL T/R Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Winbond Electronics Corporation
- Series:
- -
- Package/Case:
- 28-SOIC (0.330", 8.38mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Volatile
- Memory Format:
- SRAM
- Technology:
- SRAM
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 70ns
- Access Time:
- 70 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SO
W24257S-70LL T/R FAQ
1.How can I place an order for W24257S-70LL T/R through Aetrix?
Please submit a Request for Quotation (RFQ) for W24257S-70LL T/R 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 W24257S-70LL T/R reliable?
The price and inventory of W24257S-70LL T/R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for W24257S-70LL T/R is usually 5 days.
3.What payment methods are accepted for W24257S-70LL T/R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for W24257S-70LL T/R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for W24257S-70LL T/R?
W24257S-70LL T/R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your W24257S-70LL T/R 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 W24257S-70LL T/R?
For technical support, including W24257S-70LL T/R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your W24257S-70LL T/R requirements.
6.How does Aetrix verify that W24257S-70LL T/R is sourced from the original manufacturer or authorized distributors?
All W24257S-70LL T/R 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 W24257S-70LL T/R meets industry standards.
7.What is the process for return or replacement of W24257S-70LL T/R?
All W24257S-70LL T/R units undergo pre-shipment inspection (PSI). If there is an issue with W24257S-70LL T/R, 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 W24257S-70LL T/R part is unused and in its original packaging.
Return procedure for W24257S-70LL T/R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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