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Microchip Technology AT24C21-10SI-2.5
- Part No.:
- AT24C21-10SI-2.5
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AT24C21-10SI-2.5.pdf
- Description:
- IC EEPROM 1KBIT I2C 100KHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,737
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Product details
Overview
AT24C21-10SI-2.5 from Microchip Technology (formerly Atmel) is a 1K-bit (128 × 8) serial EEPROM with dual-mode 2-wire interface, supporting both Transmit-only Mode (DDC1™ compliant) and Bidirectional Mode (DDC2™ compliant). It operates from 2.5V to 5.5V, features 8-byte page write, self-timed 10 ms max write cycle, and is rated for industrial temperature range (−40°C to +85°C). It is used in monitor identification, display configuration storage, and embedded system parameter retention.
For engineers reviewing the AT24C21-10SI-2.5 datasheet, AT24C21-10SI-2.5 pinout, AT24C21-10SI-2.5 application, or AT24C21-10SI-2.5 equivalent, key selection considerations include DDC1/DDC2 mode compatibility, VCLK/SCL dual-clock architecture, industrial-grade endurance (1 million write cycles), 100 kHz clock support at 2.5V, and JEDEC SOIC-8 packaging with GND/VCC/SDA/SCL/VCLK pin assignment.
Technical Context
The AT24C21-10SI-2.5 implements two independent operational modes: Transmit-only Mode uses VCLK as clock input and SDA as unidirectional output for continuous memory streaming (e.g., EDID broadcast), while Bidirectional Mode uses SCL for I²C-compatible read/write control with full byte/page addressing. Mode transition occurs only once per power cycle - from Transmit-only to Bidirectional via valid SCL falling edge.
It features Schmitt-triggered, noise-filtered SDA/SCL inputs; write protection activated by grounding VCLK in Bidirectional Mode; and internal low-VCC detector disabling write logic below 1.5V. Memory organization is fixed at 128 words × 8 bits, with 7-bit address space and no hardware address pins (A0–A2 are NC).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 1024 bits (128 × 8), enabling compact configuration storage without external address decoding |
| Supply Voltage Range | 2.5V to 5.5V - supports direct integration into 2.5V, 3.3V, and 5V systems without level shifters |
| Max Clock Frequency | 100 kHz at 2.5V - ensures reliable timing margin in low-voltage DDC1/DDC2 monitor interfaces |
| Write Cycle Time | 10 ms maximum - defines minimum interval between write commands; requires polling or timeout handling |
| Endurance | 1 million write cycles - suitable for firmware parameter logging with frequent updates |
| Data Retention | 100 years at 25°C - guarantees long-term integrity of calibration or identity data across product lifetime |
| ESD Protection | >3000V HBM - provides robustness against handling and system-level ESD events in display subsystems |
Pinout & Package
AT24C21-10SI-2.5 is packaged in an 8-lead JEDEC SOIC (8S1), 0.150" wide, with gull-wing leads. Pin 1 is marked, and the package is RoHS-compliant and moisture-sensitive level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (NC) | No Connect | Unused pin; must remain floating or unconnected - not bonded internally |
| 2 (NC) | No Connect | Unused pin; no internal connection - PCB pad may be omitted or left unconnected |
| 3 (NC) | No Connect | Unused pin; no function - avoids confusion with legacy pinouts requiring A0/A1/A2 |
| 4 (GND) | Ground Reference | System return path for all internal circuitry; must be low-impedance connection to PCB ground plane |
| 5 (VCC) | Power Supply | 2.5V–5.5V supply input; requires local 0.1 µF ceramic decoupling capacitor |
| 6 (VCLK) | Transmit-only Clock Input | Drives serial output in DDC1 mode; must be held high during write operations in Bidirectional Mode |
| 7 (SCL) | Bidirectional Mode Clock | Triggers mode transition on falling edge; controls I²C timing in DDC2 mode; ignored in Transmit-only Mode |
| 8 (SDA) | Serial Data I/O | Open-drain bidirectional bus line; requires external pull-up (typically 2.2–10 kΩ) to VCC |
Key Features
| Feature | Design Value |
|---|---|
| DDC1™/DDC2™ Compliance | Enables plug-and-play EDID communication in VGA/DVI/HDMI monitors without protocol translation |
| Dual-Mode Operation | Eliminates need for separate one-time-programmable and reprogrammable EEPROMs in display systems |
| VCLK-Grounded Write Protection | Hardware-enforced ROM lock prevents accidental overwrites during system boot or firmware update |
| 8-Byte Page Write | Reduces I²C transaction overhead by up to 8× vs. byte-write for block configuration updates |
| Industrial Temperature Rating | Validated operation from −40°C to +85°C supports deployment in commercial and industrial display enclosures |
Applications
| Monitor EDID Storage | Display Configuration Memory |
|---|---|
Use Scenario: Storing Extended Display Identification Data (EDID) in LCD/LED monitors for automatic resolution and timing negotiation with host GPUs. IC Role / Device Role / Timing Role: Nonvolatile memory serving as DDC1-compliant serial transmitter of fixed 128-byte EDID block upon VCLK strobing. Use Value: Enables hot-plug detection and plug-and-play compatibility without host-side firmware intervention or external controller. | Use Scenario: Retaining user-adjusted brightness, contrast, color temperature, and input source settings across power cycles in digital signage displays. IC Role / Device Role / Timing Role: Bidirectional I²C EEPROM providing byte-addressable read/write access for real-time parameter updates via microcontroller. Use Value: Ensures consistent visual experience and eliminates factory recalibration after power loss or firmware reset. |
| Embedded System Calibration Data | Industrial Panel PC Identity Module |
Use Scenario: Storing sensor calibration coefficients, ADC offset/gain values, and thermal compensation tables in medical or test equipment. IC Role / Device Role / Timing Role: Low-voltage (2.5V) serial EEPROM accessed during system initialization to load correction parameters into MCU RAM. Use Value: Maintains measurement accuracy over time and temperature without requiring battery-backed SRAM or complex NVM drivers. | Use Scenario: Hosting unique device identifiers, MAC address fragments, and firmware version stamps in ruggedized panel PCs for asset tracking and secure boot verification. IC Role / Device Role / Timing Role: Industrial-grade EEPROM with 1M write endurance, accessed via I²C during BIOS POST or bootloader execution. Use Value: Supports field-upgradable identity data while meeting extended operating temperature and long-life reliability requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT24C02C-SSHM-T | 2K-bit (256 × 8), no VCLK pin, standard I²C-only (no DDC1 mode), 400 kHz max at 2.5V | Lacks Transmit-only Mode; unsuitable for EDID broadcast but simpler for general-purpose I²C config storage | Select when DDC1 functionality is unnecessary and higher density or faster clock is preferred |
| STMicro M24C02-RMN6TP | 2K-bit, standard I²C interface only, no VCLK or DDC1 support, 1 MHz max at 5V (not rated at 2.5V) | Not DDC1/DDC2 compliant; requires external logic for EDID emulation; lower voltage margin at 2.5V | Choose for cost-sensitive, non-monitor applications where industrial temp rating and 2K capacity outweigh DDC feature loss |
Compared with AT24C21-10SI-2.5, AT24C02C-SSHM-T offers double memory and higher speed but omits DDC1 mode and VCLK, while M24C02-RMN6TP lacks low-voltage timing validation and DDC compliance - making AT24C21-10SI-2.5 uniquely suited for monitor ID and dual-protocol embedded storage.
Availability
AT24C21-10SI-2.5 is available at Aetrix Electronics and suitable for monitor EDID storage, display configuration memory, and embedded system calibration data requiring stable component supply across industrial temperature ranges and long product lifecycles.
Supply support for AT24C21-10SI-2.5 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 is a global semiconductor company delivering smart, connected, and secure embedded control solutions, with leadership in microcontrollers, analog, FPGA, and memory products.
The AT24C21-10SI-2.5 belongs to Microchip's legacy Atmel serial EEPROM family, designed specifically for display interface standards (DDC1/DDC2) and low-voltage embedded configuration storage where dual-mode flexibility and industrial reliability are critical.
FAQ
What is the primary functional distinction of AT24C21-10SI-2.5 versus standard I²C EEPROMs?
The AT24C21-10SI-2.5 uniquely supports two independent protocols: Transmit-only Mode (DDC1™) using VCLK/SDA for EDID streaming, and Bidirectional Mode (DDC2™) using SCL/SDA for standard I²C read/write. Unlike conventional EEPROMs, it transitions permanently from Transmit-only to Bidirectional Mode on first SCL falling edge - a hardware-level feature absent in AT24C02 or M24C02 devices. This makes AT24C21-10SI-2.5 essential for monitor identification where both broadcast and programmable access are required.
Does AT24C21-10SI-2.5 require external pull-up resistors on SDA and SCL lines?
Yes, AT24C21-10SI-2.5 requires external pull-up resistors on both SDA and SCL lines because its outputs are open-drain. A typical value is 4.7 kΩ to VCC, though 2.2 kΩ may be used for faster rise times at 100 kHz. Note that VCLK is a CMOS input and does not require pull-up. The AT24C21-10SI-2.5 datasheet specifies input leakage current ≤1.0 µA, confirming that weak internal pull-ups are not provided - external biasing is mandatory for proper bus operation in either mode.
How is write protection implemented on AT24C21-10SI-2.5, and is it reversible?
Write protection on AT24C21-10SI-2.5 is enabled by connecting the VCLK pin to GND while the device is in Bidirectional Mode - this locks the entire memory array as read-only. The protection is hardware-based and fully reversible: removing the GND connection restores write capability immediately, with no command or timing sequence required. Importantly, this mechanism does not affect Transmit-only Mode operation, and AT24C21-10SI-2.5 retains full EDID broadcast functionality even with VCLK grounded. No software lock bits or password protection is involved.
What is the significance of the "-10SI-2.5" suffix in AT24C21-10SI-2.5?
The "-10SI-2.5" suffix in AT24C21-10SI-2.5 specifies three critical attributes: "10" denotes maximum 10 ms write cycle time; "SI" indicates Industrial temperature grade (−40°C to +85°C) in JEDEC SOIC-8 package (8S1); and "-2.5" confirms guaranteed operation down to 2.5V supply (2.5V–5.5V range). This distinguishes it from commercial-grade variants like AT24C21-10SC-2.5 (0°C to +70°C) and non-low-voltage versions. All three elements are validated in the official Microchip ordering information table.
Can AT24C21-10SI-2.5 be used in new designs despite being a legacy Atmel part?
Yes, AT24C21-10SI-2.5 remains actively manufactured and supported by Microchip Technology, with full datasheet documentation, validated industrial temperature performance, and ongoing distribution through authorized channels. Its DDC1/DDC2 dual-mode capability is not replicated in newer Microchip EEPROM families (e.g., AT24C02C), making AT24C21-10SI-2.5 the only qualified solution for legacy and new monitor ID applications requiring EDID broadcast plus reprogrammability. Lifecycle status is active per Microchip's product change notifications.
AT24C21-10SI-2.5 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 1Kbit
- Memory Organization:
- 128 x 8
- Memory Interface:
- I2C
- Clock Frequency:
- 100 kHz
- Write Cycle Time - Word, Page:
- 10ms
- Access Time:
- 3.5 µs
- Voltage - Supply:
- 2.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
AT24C21-10SI-2.5 FAQ
1.How can I place an order for AT24C21-10SI-2.5 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT24C21-10SI-2.5 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 AT24C21-10SI-2.5 reliable?
The price and inventory of AT24C21-10SI-2.5 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT24C21-10SI-2.5 is usually 5 days.
3.What payment methods are accepted for AT24C21-10SI-2.5?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT24C21-10SI-2.5 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT24C21-10SI-2.5?
AT24C21-10SI-2.5 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT24C21-10SI-2.5 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 AT24C21-10SI-2.5?
For technical support, including AT24C21-10SI-2.5 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT24C21-10SI-2.5 requirements.
6.How does Aetrix verify that AT24C21-10SI-2.5 is sourced from the original manufacturer or authorized distributors?
All AT24C21-10SI-2.5 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 AT24C21-10SI-2.5 meets industry standards.
7.What is the process for return or replacement of AT24C21-10SI-2.5?
All AT24C21-10SI-2.5 units undergo pre-shipment inspection (PSI). If there is an issue with AT24C21-10SI-2.5, 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 AT24C21-10SI-2.5 part is unused and in its original packaging.
Return procedure for AT24C21-10SI-2.5:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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