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Microchip Technology 24CS256T-E/Q4B66KVAO
- Part No.:
- 24CS256T-E/Q4B66KVAO
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-UFDFN Exposed Pad
- Datasheet:
-
24CS256T-E/Q4B66KVAO.pdf
- Description:
- IC EEPROM 256KBIT I2C 8UDFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,867
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Product details
Overview
24CS256T-E/Q4B66KVAO from Microchip Technology is a 256-Kbit I²C serial EEPROM organized as 32,768 × 8-bit, supporting high-speed mode up to 3.4 MHz, 1.7V–5.5V operation, and built-in ECC for single-bit error correction. It integrates a 128-bit factory-programmed serial number and user-lockable 64-byte ID page, targeting automotive infotainment storage, industrial sensor calibration data retention, and secure boot configuration in AEC-Q100-compliant systems.
For engineers reviewing the 24CS256T-E/Q4B66KVAO datasheet, 24CS256T-E/Q4B66KVAO pinout, 24CS256T-E/Q4B66KVAO application, or 24CS256T-E/Q4B66KVAO equivalent, key selection criteria include its extended temperature range (–40°C to +125°C), hardware/software write protection flexibility, 5 ms max self-timed write cycle, and compatibility with legacy 24AA256/24LC256 devices in shared-bus multi-drop configurations.
Technical Context
The 24CS256T-E/Q4B66KVAO implements a two-wire I²C interface with Schmitt-trigger inputs and slope-controlled outputs to suppress noise and ground bounce. Its memory architecture comprises a 256-Kbit main array (0000h–7FFFh) and a dedicated 1-Kbit security register split into read-only 128-bit serial number (0800h–080Fh) and lockable 64-byte ID page (0840h–087Fh).
Device behavior is modulated via a configurable register enabling either legacy WP-pin-based full-array protection or enhanced software-defined zone protection across eight independent 32-Kbit blocks. The Configuration register can be permanently locked, and an Error Correction State (ECS) latch reports ECC invocation status during reads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8-bit), organized in 512 pages of 64 bytes each - enables efficient bulk writes without crossing page boundaries. |
| I²C Speed Support | Up to 3.4 MHz (High-Speed mode), plus 1 MHz / 400 kHz / 100 kHz - supports fast firmware updates and real-time parameter logging in resource-constrained hosts. |
| Write Cycle Time | ≤5 ms maximum self-timed byte/page write - eliminates need for external polling or timeout management in host firmware. |
| Operating Voltage | 1.7 V to 5.5 V - interoperates with 1.8 V logic microcontrollers and 5 V legacy systems without level-shifting. |
| Temperature Range | –40°C to +125°C (Extended grade) - qualified per AEC-Q100 Grade 1 for under-hood automotive applications. |
| Data Retention | >200 years at 55°C - ensures long-term integrity of calibration coefficients and cryptographic keys in sealed modules. |
| Endurance | 1,000,000 erase/write cycles - supports frequent runtime parameter logging in industrial controllers. |
| ECC Capability | Corrects up to one bit error per four-byte read - mitigates soft errors in safety-critical storage without host-side correction logic. |
Pinout & Package
24CS256T-E/Q4B66KVAO is packaged in an 8-lead UDFN (2 mm × 3 mm, 0.5 mm pitch) with wettable flank terminations, optimized for automated optical inspection (AOI) and high-reliability solder joint formation in automotive PCB assemblies.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0 | Hardware Address Input | LSB of 3-bit device address; hardwired to VSS or VCC to enable up to eight devices on same I²C bus - required for multi-sensor node addressing. |
| A1 | Hardware Address Input | Middle bit of 3-bit device address; sets unique client address alongside A0/A2 - essential for daisy-chained EEPROM configurations. |
| A2 | Hardware Address Input | MSB of 3-bit device address; determines I²C slave address offset - used in modular system designs with interchangeable daughterboards. |
| VSS | Ground Reference | Primary return path for all internal circuitry; must be low-impedance connection to minimize noise coupling into SDA/SCL lines. |
| SDA | Serial Data Bidirectional Line | Open-drain I²C data line requiring external pull-up; supports bidirectional byte transfers and ACK/NACK signaling - interfaces directly with MCU I²C peripherals. |
| SCL | Serial Clock Input | Master-generated clock synchronizing all data transfers; slope control reduces EMI and prevents false edge detection in noisy environments. |
| WP | Hardware Write-Protect | Active-high pin disabling all writes when tied to VCC; complements software zone protection - provides fail-safe lock for critical boot parameters. |
| VCC | Power Supply | 1.7–5.5 V supply input; internal POR circuit enforces 100 µs delay after stable VCC before accepting commands - prevents spurious writes during power ramp. |
Key Features
| Feature | Design Value |
|---|---|
| Factory-Programmed 128-Bit Serial Number | Uniquely identifies each unit across CS-series EEPROMs - eliminates manufacturing serialization overhead and enables secure device binding. |
| User-Programmable & Lockable 64-Byte ID Page | Stores immutable application-specific identifiers (e.g., MAC address, calibration hash); software-lockable to prevent tampering post-deployment. |
| Configurable Write Protection Mode | Selects between hardware WP-pin full-array lock or software-defined protection of eight independent 32-Kbit zones - supports hierarchical data security policies. |
| Built-In ECC Logic with ECS Latch | Corrects single-bit errors in real time and latches error occurrence status in Configuration register - enables host diagnostics without interrupting read operations. |
| I²C Manufacturer ID Register | Returns unique 24-bit identifier confirming device authenticity - prevents counterfeit parts from masquerading as genuine Microchip 24CS256 units. |
| AEC-Q100 Automotive Qualification | Qualified to Grade 1 (–40°C to +125°C) with full reliability testing - meets functional safety requirements for ASIL-B–capable systems. |
Applications
| Automotive Infotainment Tuner Calibration | Industrial PLC Configuration Storage |
|---|---|
Use Scenario: Storing RF tuning parameters and channel presets for AM/FM/HD Radio modules in vehicle head units. IC Role / Device Role / Timing Role: Nonvolatile configuration store accessed during boot and runtime via I²C; retains settings across ignition cycles. Use Value: Factory-programmed serial number enables anti-cloning; ECC ensures parameter integrity despite EMI exposure near powertrain electronics. |
Use Scenario: Holding I/O mapping tables, PID loop coefficients, and firmware update metadata in programmable logic controllers. IC Role / Device Role / Timing Role: Persistent data repository interfaced by ARM Cortex-M7 host MCU; supports rapid reconfiguration without flash wear. Use Value: 1,000,000 write cycles accommodate daily field calibration logs; software zone protection isolates critical firmware parameters from user-modifiable settings. |
| Medical Sensor Module Identity & Calibration | Smart Energy Meter Firmware Bootloader Keys |
Use Scenario: Securing unique device identity and factory-calibrated sensor offsets in portable patient monitors. IC Role / Device Role / Timing Role: Tamper-resistant identity anchor; stores cryptographic keys and calibration data readable only after authentication handshake. Use Value: Lockable 64-byte ID page prevents unauthorized modification of medical device traceability data; AEC-Q100 qualification validates reliability in clinical environments. |
Use Scenario: Storing asymmetric key pairs and bootloader signature verification keys in utility-grade electricity meters. IC Role / Device Role / Timing Role: Secure key vault accessed exclusively during secure boot sequence; isolated from application firmware partition. Use Value: Hardware WP pin provides physical write-disable during normal operation; ECC protects key integrity against radiation-induced bit flips in outdoor deployments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT24C256C-SSHL-T | No built-in ECC, no security register, 1 MHz max I²C speed, –40°C to +85°C only | Lacks serial number and zone-level write protection; suitable for cost-sensitive consumer products without safety/security mandates | Select only if ECC, extended temp, or secure ID features are unnecessary and legacy AT24C footprint is required. |
| 24AA256-I/P | Same pinout but no High-Speed mode (max 400 kHz), no 128-bit serial number, no software-configurable write protection | Compatible for basic parameter storage in industrial controls where bus speed and security are secondary | Choose when migrating from older Microchip EEPROMs and high-speed or cryptographic features are not needed. |
Compared with AT24C256C-SSHL-T and 24AA256-I/P, the 24CS256T-E/Q4B66KVAO delivers higher reliability through ECC, broader operating range, and hardware-enforced security primitives - making it the sole option among these three qualified for AEC-Q100 automotive use cases requiring data integrity and device authentication.
Availability
24CS256T-E/Q4B66KVAO is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLCs, medical sensor modules, and smart energy metering applications requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for 24CS256T-E/Q4B66KVAO 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
Microchip Technology Inc. is a leading provider of microcontroller, analog, FPGA, and memory solutions, serving automotive, industrial, communications, and consumer markets with vertically integrated silicon and development tools.
The 24CS256T-E/Q4B66KVAO belongs to Microchip's CS-series serial EEPROM family, designed specifically for automotive and high-reliability applications demanding extended temperature operation, built-in security primitives, and robust error resilience in electrically noisy environments.
FAQ
What is the maximum I²C clock frequency supported by the 24CS256T-E/Q4B66KVAO?
The 24CS256T-E/Q4B66KVAO supports I²C High-Speed mode up to 3.4 MHz when operating at VCC ≥ 2.5 V and within the Industrial temperature range. At lower voltages or extended temperature, it operates at standard speeds (1 MHz, 400 kHz, or 100 kHz). This enables faster firmware updates and real-time parameter logging compared to legacy EEPROMs limited to 400 kHz.
Does the 24CS256T-E/Q4B66KVAO require external pull-up resistors on SDA and SCL lines?
Yes, the 24CS256T-E/Q4B66KVAO requires external pull-up resistors on both SDA and SCL lines because its I²C interface uses open-drain outputs. Recommended values are 330 Ω for 3.4 MHz operation, 2 kΩ for 1 MHz, and 10 kΩ for 100 kHz - selected based on bus capacitance and speed requirements to meet rise/fall time specifications.
How does the built-in ECC in the 24CS256T-E/Q4B66KVAO function during read operations?
The 24CS256T-E/Q4B66KVAO applies ECC correction automatically during every read operation across four-byte boundaries, correcting up to one flipped bit per group. When correction occurs, the Error Correction State (ECS) latch in the Configuration register is set - allowing host firmware to log or flag potential memory degradation without halting operation.
Can the 128-bit serial number in the 24CS256T-E/Q4B66KVAO be overwritten or modified?
No, the 128-bit serial number in the 24CS256T-E/Q4B66KVAO is factory-programmed and permanently read-only. It resides in the first 16 bytes (0800h–080Fh) of the Security register and cannot be altered, erased, or reprogrammed - ensuring unforgeable device identity for traceability and anti-counterfeiting purposes.
What write protection options are available on the 24CS256T-E/Q4B66KVAO?
The 24CS256T-E/Q4B66KVAO offers dual write protection: hardware-based via the WP pin (disables all writes when high), and software-configurable via the Configuration register (enables zone-level locking of eight independent 32-Kbit blocks). Once configured, the register can be permanently locked to prevent further changes - providing layered security for critical data.
24CS256T-E/Q4B66KVAO Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-UFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- -
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- I2C
- Clock Frequency:
- 1 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- 400 ns
- Voltage - Supply:
- 1.7V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-UDFN (2x3)
24CS256T-E/Q4B66KVAO FAQ
1.How can I place an order for 24CS256T-E/Q4B66KVAO through Aetrix?
Please submit a Request for Quotation (RFQ) for 24CS256T-E/Q4B66KVAO 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 24CS256T-E/Q4B66KVAO reliable?
The price and inventory of 24CS256T-E/Q4B66KVAO are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 24CS256T-E/Q4B66KVAO is usually 5 days.
3.What payment methods are accepted for 24CS256T-E/Q4B66KVAO?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 24CS256T-E/Q4B66KVAO transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 24CS256T-E/Q4B66KVAO?
24CS256T-E/Q4B66KVAO orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 24CS256T-E/Q4B66KVAO 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 24CS256T-E/Q4B66KVAO?
For technical support, including 24CS256T-E/Q4B66KVAO datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 24CS256T-E/Q4B66KVAO requirements.
6.How does Aetrix verify that 24CS256T-E/Q4B66KVAO is sourced from the original manufacturer or authorized distributors?
All 24CS256T-E/Q4B66KVAO 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 24CS256T-E/Q4B66KVAO meets industry standards.
7.What is the process for return or replacement of 24CS256T-E/Q4B66KVAO?
All 24CS256T-E/Q4B66KVAO units undergo pre-shipment inspection (PSI). If there is an issue with 24CS256T-E/Q4B66KVAO, 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 24CS256T-E/Q4B66KVAO part is unused and in its original packaging.
Return procedure for 24CS256T-E/Q4B66KVAO:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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