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Microchip Technology AT24C21-10PC-2.5
- Part No.:
- AT24C21-10PC-2.5
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
AT24C21-10PC-2.5.pdf
- Description:
- IC EEPROM 1KBIT I2C 100KHZ 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,536
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Product details
Overview
AT24C21-10PC-2.5 from Atmel (now Microchip) is a 1K-bit (128 × 8) 2-wire serial EEPROM optimized for DDC1™/DDC2™ monitor identification and low-voltage embedded configuration storage. It operates from 2.5V to 5.5V, supports 100 kHz clock frequency at 2.5V, features self-timed write cycles (≤10 ms), and delivers 1 million write endurance with 100-year data retention. Its dual-mode operation-Transmit-only (VCLK-clocked streaming) and Bidirectional (SCL-based I²C-like protocol)-enables plug-and-play display EDID delivery and flexible system-level memory access.
For engineers reviewing the AT24C21-10PC-2.5 datasheet, AT24C21-10PC-2.5 pinout, AT24C21-10PC-2.5 application, or AT24C21-10PC-2.5 equivalent, key selection considerations include its 2.5V–5.5V supply range, VCLK/SCL dual-clock architecture, 8-byte page write capability, write protection via VCLK-to-GND, and PDIP-8 packaging for legacy board compatibility and manual prototyping.
Technical Context
The AT24C21-10PC-2.5 implements two independent communication modes: Transmit-only Mode uses VCLK as a unidirectional clock input to stream full memory contents (MSB-first, 8-bit words + don't-care bit) on SDA, with initialization-dependent start address (00H or 7FH). Bidirectional Mode activates on valid SCL high-to-low transition and supports standard byte/page reads/writes using I²C-style START/STOP/ACK handshaking.
Its memory is organized as 128 × 8 bits with 7-bit addressing; no A0/A1/A2 pins are present, so device addressing is fixed. Write protection is hardware-enforced by grounding VCLK in Bidirectional Mode, disabling all writes. Noise immunity is achieved via Schmitt-trigger inputs and internal filtering on SDA/SCL, while low-VCC detection disables write logic below 1.5V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 1024 bits (128 × 8), enabling compact EDID storage or boot configuration without external address decoding |
| Supply Voltage Range | 2.5V to 5.5V - supports direct interface with 2.5V, 3.3V, and 5V logic domains without level shifters |
| Max Clock Frequency | 100 kHz at 2.5V - ensures reliable timing margin in noise-prone display interface environments |
| Write Cycle Time | ≤10 ms (self-timed) - eliminates need for external write-complete polling delay in most firmware implementations |
| Endurance & Retention | 1 million write cycles / 100 years data retention - suitable for infrequent but mission-critical parameter storage (e.g., calibration, serial ID) |
| ESD Protection | >3000V HBM - robust enough for handling during monitor assembly and field service |
| Operating Temperature | 0°C to +70°C (Commercial grade) - validated for desktop/laptop display subsystems and industrial HMI panels |
Pinout & Package
AT24C21-10PC-2.5 is supplied in an 8-pin PDIP (package code 8P3), 0.300" wide, through-hole package compatible with legacy socketing and manual soldering. Pin 1 is index-marked; pins 1–4 and 5–8 are arranged across two parallel rows.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| NC | No-connect (pins 1–3) | Unused; must remain floating - no internal connection or function |
| GND | Ground reference | Common return path for VCC, SDA, SCL, and VCLK; required for noise suppression and logic threshold stability |
| VCC | Power supply input | Accepts 2.5V–5.5V; powers internal logic, memory array, and I/O buffers |
| VCLK | Transmit-only mode clock input | Drives serial output streaming in power-up default mode; also enables write when held high in Bidirectional Mode |
| SCL | Bidirectional mode clock input | Triggers mode switch from Transmit-only; controls timing of I²C-style read/write transactions |
| SDA | Serial bidirectional data I/O | Open-drain output/input shared across both modes; requires external pull-up (typically 2.2–10 kΩ) |
Key Features
| Feature | Design Value |
|---|---|
| DDC1™/DDC2™ Compliance | Native support for VESA Display Data Channel protocols - enables immediate integration into monitor EDID circuits without translation logic |
| Dual-Mode Architecture | Hardware-selectable Transmit-only (VCLK-driven) and Bidirectional (SCL-driven) operation - eliminates need for external mode control logic or firmware negotiation |
| Hardware Write Protection | VCLK tied to GND disables all writes in Bidirectional Mode - prevents accidental overwrites during system debug or field updates |
| 8-Byte Page Write | Reduces write transaction overhead by up to 8× vs. byte-write - improves efficiency when updating multi-byte configuration blocks (e.g., gamma tables) |
| Noise-Suppressed Inputs | Schmitt-trigger + internal filtering on SDA/SCL - maintains reliable operation in electrically noisy video interface environments (e.g., near switching regulators or LVDS transmitters) |
Applications
| Monitor EDID Storage | Legacy Industrial HMI Configuration |
|---|---|
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 providing standardized I²C-accessible display descriptor data; operates in Bidirectional Mode during GPU read, Transmit-only Mode during hot-plug detection. Use Value: Enables plug-and-play display compatibility without host-side firmware modification; VCLK streaming allows immediate EDID availability post-power-up before system initialization. |
Use Scenario: Retaining calibrated sensor offsets, user preferences, and operational limits in panel-mounted HMIs with 5V or 3.3V microcontrollers. IC Role / Device Role / Timing Role: Configuration storage peripheral interfaced via standard I²C bus; leverages page write to update multi-parameter sets atomically. Use Value: Eliminates battery-backed RAM; 1M endurance supports decades of field recalibration; 2.5V min supply ensures operation during brown-out conditions. |
| Desktop Peripheral Identity | Embedded System Boot Parameters |
Use Scenario: Holding vendor ID, product ID, and firmware revision in USB-to-VGA adapters and docking stations. IC Role / Device Role / Timing Role: Read-only identity source during enumeration; accessed via Transmit-only Mode for fast, deterministic response to host DDC queries. Use Value: Reduces BOM count by replacing discrete ID ROMs; fixed start address (00H/7FH) allows predictable EDID structure alignment without software address management. |
Use Scenario: Storing bootloader-configurable options (e.g., UART baud rate, watchdog timeout, fail-safe defaults) in medical or test equipment. IC Role / Device Role / Timing Role: Persistent parameter store accessed early in boot sequence; write protection prevents corruption during power transitions. Use Value: Ensures safe recovery after unexpected reset; 100-year retention guarantees parameter integrity across product lifecycle without maintenance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT24C02-10PC-2.5 | 2K-bit (256 × 8), identical 2.5V–5.5V supply and 100 kHz speed; adds A0/A1 pins for multi-device bus addressing | Supports larger EDID extensions or dual-parameter banks; requires address pin routing not needed for AT24C21-10PC-2.5 | Select when >1K storage or bus expandability is required; otherwise, AT24C21-10PC-2.5 offers optimal footprint and cost for basic DDC use. |
| M95010-WMN6TP | 1K-bit SPI EEPROM (not 2-wire); 2.5V–5.5V, 10 MHz max clock; no VCLK/SCL dual-mode capability | Requires SPI host interface instead of I²C/DDC; lacks native Transmit-only streaming for EDID | Choose only if system already uses SPI peripherals and DDC compliance is not required; not a functional substitute for monitor ID applications. |
Compared with AT24C02-10PC-2.5 and M95010-WMN6TP, the AT24C21-10PC-2.5 uniquely combines DDC1/2 compliance, VCLK-driven streaming, and fixed-address simplicity - making it irreplaceable for cost-sensitive, standards-compliant display identification where minimal pin count and guaranteed EDID delivery are mandatory.
Availability
AT24C21-10PC-2.5 is available at Aetrix Electronics and suitable for monitor EDID implementation, industrial HMI configuration storage, and embedded boot parameter retention requiring stable component supply across long-lifecycle programs.
Supply support for AT24C21-10PC-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 (formerly Atmel) is a global semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions for industrial, automotive, and consumer applications.
The AT24C21-10PC-2.5 belongs to Atmel's legacy 2-wire serial EEPROM family, designed specifically for VESA DDC-compliant display identification and low-voltage embedded configuration storage in space-constrained systems.
FAQ
What is the primary function of the VCLK pin on the AT24C21-10PC-2.5?
The VCLK pin serves as the dedicated clock input for Transmit-only Mode, enabling the AT24C21-10PC-2.5 to stream its entire memory contents on SDA upon power-up. In Bidirectional Mode, VCLK must be held high to enable write operations; grounding VCLK provides hardware write protection. Unlike SCL, VCLK is ignored during Bidirectional Mode data transfers except for write-enable control.
Does the AT24C21-10PC-2.5 support standard I²C addressing?
No - the AT24C21-10PC-2.5 does not implement standard 7-bit I²C addressing. It uses a fixed device address with no A0/A1/A2 pins; the address word is hardwired and lacks configurable bits. Communication relies on mode-specific protocols: VCLK-synchronized streaming in Transmit-only Mode and simplified START/STOP/ACK sequences in Bidirectional Mode, distinct from full I²C compliance.
Can the AT24C21-10PC-2.5 be used in place of a standard AT24C01 or AT24C02 EEPROM?
The AT24C21-10PC-2.5 is not a drop-in replacement for AT24C01/AT24C02 due to architectural differences: it lacks A0–A2 address pins, uses dual-clock (VCLK/SCL) signaling, and features Transmit-only Mode. While it shares 2-wire interface and voltage range, firmware and hardware design must explicitly support its unique mode-switching behavior and fixed addressing - direct substitution will cause communication failure.
What is the significance of the "-10PC-2.5" suffix in AT24C21-10PC-2.5?
The "-10PC-2.5" suffix specifies three critical attributes of the AT24C21-10PC-2.5: "10" denotes maximum 10 ms write cycle time; "PC" indicates 8-pin PDIP (0.300" wide) packaging; and "-2.5" confirms guaranteed operation down to 2.5V supply voltage (2.5V–5.5V range), distinguishing it from higher-voltage variants like -10PC.
How does write protection work on the AT24C21-10PC-2.5?
Write protection on the AT24C21-10PC-2.5 is activated by connecting the VCLK pin to GND while the device is in Bidirectional Mode. This hardware lock disables all write operations - including byte and page writes - rendering the memory effectively read-only. The protection remains active until VCLK is returned high and the device is power-cycled or reset; no software command can override this state.
AT24C21-10PC-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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
AT24C21-10PC-2.5 FAQ
1.How can I place an order for AT24C21-10PC-2.5 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT24C21-10PC-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 AT24C21-10PC-2.5 reliable?
The price and inventory of AT24C21-10PC-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 AT24C21-10PC-2.5 is usually 5 days.
3.What payment methods are accepted for AT24C21-10PC-2.5?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT24C21-10PC-2.5 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT24C21-10PC-2.5?
AT24C21-10PC-2.5 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT24C21-10PC-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 AT24C21-10PC-2.5?
For technical support, including AT24C21-10PC-2.5 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT24C21-10PC-2.5 requirements.
6.How does Aetrix verify that AT24C21-10PC-2.5 is sourced from the original manufacturer or authorized distributors?
All AT24C21-10PC-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 AT24C21-10PC-2.5 meets industry standards.
7.What is the process for return or replacement of AT24C21-10PC-2.5?
All AT24C21-10PC-2.5 units undergo pre-shipment inspection (PSI). If there is an issue with AT24C21-10PC-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 AT24C21-10PC-2.5 part is unused and in its original packaging.
Return procedure for AT24C21-10PC-2.5:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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