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Microchip Technology AT24C21-10PI-2.5
- Part No.:
- AT24C21-10PI-2.5
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
AT24C21-10PI-2.5.pdf
- Description:
- IC EEPROM 1KBIT I2C 100KHZ 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,654
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Product details
Overview
AT24C21-10PI-2.5 from Microchip Technology (formerly Atmel) is a 1K-bit (128 × 8) serial EEPROM with dual-mode operation: Transmit-only Mode (DDC1™ compliant) for monitor identification and Bidirectional Mode (DDC2™ compliant) for full read/write control via standard 2-wire interface. It operates from 2.5V to 5.5V, supports 100 kHz clock frequency at 2.5V, features 8-byte page write, and delivers 1 million write cycles with 100-year data retention. It is used in display EDID storage and embedded configuration memory systems.
For engineers reviewing the AT24C21-10PI-2.5 datasheet, AT24C21-10PI-2.5 pinout, AT24C21-10PI-2.5 application, or AT24C21-10PI-2.5 equivalent, key selection considerations include its dual-clock architecture (SCL and VCLK), industrial temperature range (−40°C to +85°C), PDIP/SOIC package options, DDC compliance, and write-protection via VCLK grounding.
Technical Context
The AT24C21-10PI-2.5 implements two independent 2-wire protocols: Transmit-only Mode uses VCLK as clock input and SDA as unidirectional output, delivering continuous memory stream starting from address 00H or 7FH based on SDA state during initialization; Bidirectional Mode uses SCL for clocking and SDA for bidirectional I²C-compatible communication after a valid high-to-low transition on SCL.
It features Schmitt-trigger and noise-filtered inputs, internal low-VCC detector disabling write logic below 1.5V, and hardware write protection activated when VCLK is tied to GND in Bidirectional Mode - making the entire memory read-only. Memory organization is fixed at 128 words × 8 bits with 7-bit addressing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 1024 bits (128 × 8), enabling compact nonvolatile storage for EDID blocks or device configuration data |
| Supply Voltage Range | 2.5V to 5.5V - supports low-voltage system integration without level-shifting |
| Max Clock Frequency | 100 kHz at 2.5V - ensures reliable timing margin in noise-prone DDC bus environments |
| Write Cycle Time | 10 ms max - defines minimum interval between write operations; self-timed, no external polling required |
| Endurance | 1 million write cycles - suitable for infrequent but critical configuration updates over product lifetime |
| Data Retention | 100 years at 25°C - guarantees long-term integrity of stored display or calibration data |
| Operating Temperature | −40°C to +85°C (Industrial grade) - validated for use in monitors, set-top boxes, and industrial HMI displays |
Pinout & Package
AT24C21-10PI-2.5 is supplied in 8-pin PDIP (package code 8P3) per JEDEC MS-001 BA standard, with 0.300" body width and through-hole mounting. Pin 4 is GND, Pin 5 is VCC, Pin 6 is VCLK, Pin 7 is SCL, Pin 8 is SDA; Pins 1–3 are No Connect (NC).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1–3 (NC) | No Connect | Unbonded; must remain floating or grounded - no electrical function |
| Pin 4 (GND) | Ground Reference | Return path for all internal circuitry; required for noise suppression and VCLK-based write protection |
| Pin 5 (VCC) | Power Supply | 2.5V–5.5V supply input; internal voltage detector disables writes below 1.5V |
| Pin 6 (VCLK) | Transmit-only Clock Input | Drives serial output in Transmit-only Mode; grounding enables hardware write protection in Bidirectional Mode |
| Pin 7 (SCL) | Bidirectional Clock Input | Triggers mode transition on high-to-low edge; controls timing in I²C-style read/write sequences |
| Pin 8 (SDA) | Bidirectional Data I/O | Open-drain output shared across both modes; requires external pull-up; carries EDID data stream or byte-addressed commands |
Key Features
| Feature | Design Value |
|---|---|
| DDC1™/DDC2™ Compliance | Fully implements VESA Display Data Channel standards - directly usable in monitor EDID ROM without protocol translation |
| Dual-Mode Operation | Eliminates need for separate transmit-only and I²C EEPROMs; reduces BOM count and PCB footprint in display subsystems |
| VCLK-Based Write Protection | Hardware-level memory lock achieved by grounding VCLK - prevents accidental writes without firmware intervention |
| Noise-Suppressed Inputs | Schmitt-trigger + filtering on SDA/SCL enables robust operation in electrically noisy video interface environments |
| 8-Byte Page Write | Reduces I²C bus transaction overhead vs. byte-write - improves efficiency when updating multi-byte EDID fields |
Applications
| Monitor EDID Storage | Embedded Configuration Memory |
|---|---|
Use Scenario: Storing Extended Display Identification Data (EDID) in LCD/LED monitors and projectors for automatic resolution and timing negotiation with host GPUs. IC Role / Device Role / Timing Role: Nonvolatile memory holding standardized 128-byte EDID block; accessed via DDC1™ (transmit-only) during display power-up handshake. Use Value: Enables plug-and-play interoperability without host-side driver updates; leverages VCLK-synchronized streaming for guaranteed timing compliance. | Use Scenario: Retaining factory calibration coefficients, user preferences, or network settings in industrial HMIs and medical display panels. IC Role / Device Role / Timing Role: Serial configuration store accessed via DDC2™ (bidirectional I²C) during boot or runtime by microcontroller firmware. Use Value: Supports field-updatable parameters with hardware write protection (VCLK = GND) to prevent corruption during power transients. |
| Set-Top Box HDMI Handshake | Automotive Infotainment Display |
Use Scenario: Providing EDID data to HDMI source devices (e.g., Blu-ray players) in consumer set-top boxes with integrated displays. IC Role / Device Role / Timing Role: DDC1™-compliant EEPROM responding to GPU-initiated VCLK pulses; delivers full memory contents in wraparound sequence. Use Value: Ensures HDMI link training completes within VESA-specified timing windows using deterministic transmit-only protocol. | Use Scenario: Storing display gamma tables and brightness profiles in automotive head units operating across extended temperature ranges. IC Role / Device Role / Timing Role: Industrial-grade (−40°C to +85°C) serial EEPROM interfaced via I²C for runtime read/write of display LUTs. Use Value: Guarantees data integrity under thermal cycling and EMI exposure; 100-year retention avoids recalibration during vehicle lifetime. |
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), 400 kHz max @ 2.5V, no VCLK pin or Transmit-only Mode | Standard I²C-only; lacks DDC1™ compliance and hardware write protection via VCLK | Choose when only bidirectional I²C access is needed and higher density is acceptable |
| STMicro M24C02-RMN6TP | 2K-bit, 400 kHz, same 8-lead SOIC package, no VCLK or DDC1™ support | Requires external software write protection; not certified for DDC monitor identification | Prefer for cost-sensitive industrial control where EDID functionality is unnecessary |
Compared with AT24C21-10PI-2.5, both alternatives offer higher density and faster I²C speeds but omit the dual-mode architecture essential for VESA-compliant monitor ID - making them unsuitable for DDC1™-dependent applications without redesign.
Availability
AT24C21-10PI-2.5 is available at Aetrix Electronics and suitable for monitor EDID storage, embedded configuration memory, and HDMI handshake systems requiring stable component supply across industrial temperature ranges and long product lifecycles.
Supply support for AT24C21-10PI-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 specializing in microcontrollers, analog devices, and memory solutions, with broad industrial and automotive qualification coverage.
The AT24C21-10PI-2.5 belongs to Microchip's legacy Atmel serial EEPROM family, engineered specifically for display interface compliance (DDC1/DDC2) and robust configuration storage in space-constrained, noise-sensitive applications.
FAQ
What is the primary function of the VCLK pin on the AT24C21-10PI-2.5?
The VCLK pin on the AT24C21-10PI-2.5 serves as the clock input for Transmit-only Mode (DDC1™), enabling serial output of the full memory array on SDA. In Bidirectional Mode, it acts as a hardware write-protection enable: grounding VCLK locks memory as read-only. It is not used for timing in standard I²C transactions - that role belongs exclusively to SCL. The AT24C21-10PI-2.5 relies on this dual-clock architecture to meet VESA display interface requirements without external logic.
Does the AT24C21-10PI-2.5 support standard I²C addressing and protocol?
Yes, the AT24C21-10PI-2.5 supports standard I²C addressing in Bidirectional Mode: it responds to an 8-bit device address with R/W bit, acknowledges each byte, and follows standard start/stop/acknowledge timing. However, it does not implement full I²C slave arbitration or multi-master support. Its I²C compatibility is limited to point-to-point configurations typical in display subsystems. The AT24C21-10PI-2.5 remains fully functional with common microcontroller I²C peripherals, provided VCLK is held high during bidirectional operation.
How does write protection work on the AT24C21-10PI-2.5?
Write protection on the AT24C21-10PI-2.5 is implemented by grounding the VCLK pin while the device is in Bidirectional Mode - this disables all write operations, rendering the entire memory read-only. This is a hardware-level feature requiring no firmware configuration. The AT24C21-10PI-2.5 retains this protection across power cycles until VCLK is released from GND. Unlike software lock bits, this method prevents corruption during brown-out or reset conditions, making it ideal for safety-critical display data.
What is the difference between Transmit-only Mode and Bidirectional Mode on the AT24C21-10PI-2.5?
Transmit-only Mode (activated at power-up) outputs the full 128-byte memory sequentially on SDA synchronized to VCLK edges - used for DDC1™ monitor identification. Bidirectional Mode (entered via SCL high-to-low transition) enables standard I²C-style random read/write using SCL/SDA - used for configuration updates. The AT24C21-10PI-2.5 cannot return to Transmit-only Mode without power cycle. These modes share SDA but use separate clocks, allowing one device to serve both EDID streaming and programmable storage roles.
Is the AT24C21-10PI-2.5 compatible with modern HDMI or DisplayPort sources?
Yes, the AT24C21-10PI-2.5 is fully compatible with HDMI and DisplayPort sources that perform DDC-based EDID reading, as it meets VESA DDC1™ and DDC2™ specifications. Its Transmit-only Mode delivers the required 128-byte EDID block in strict timing alignment with VCLK, satisfying HDMI 1.4+ and DisplayPort 1.2+ source requirements. The AT24C21-10PI-2.5 has been widely deployed in certified displays and remains interoperable with current graphics drivers and link training algorithms.
AT24C21-10PI-2.5 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- 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:
- Through Hole
- Supplier Device Package:
- 8-PDIP
AT24C21-10PI-2.5 FAQ
1.How can I place an order for AT24C21-10PI-2.5 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT24C21-10PI-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 AT24C21-10PI-2.5 reliable?
The price and inventory of AT24C21-10PI-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 AT24C21-10PI-2.5 is usually 5 days.
3.What payment methods are accepted for AT24C21-10PI-2.5?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT24C21-10PI-2.5 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT24C21-10PI-2.5?
AT24C21-10PI-2.5 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT24C21-10PI-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 AT24C21-10PI-2.5?
For technical support, including AT24C21-10PI-2.5 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT24C21-10PI-2.5 requirements.
6.How does Aetrix verify that AT24C21-10PI-2.5 is sourced from the original manufacturer or authorized distributors?
All AT24C21-10PI-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 AT24C21-10PI-2.5 meets industry standards.
7.What is the process for return or replacement of AT24C21-10PI-2.5?
All AT24C21-10PI-2.5 units undergo pre-shipment inspection (PSI). If there is an issue with AT24C21-10PI-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 AT24C21-10PI-2.5 part is unused and in its original packaging.
Return procedure for AT24C21-10PI-2.5:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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