My Inquiry
My Account
Microchip Technology 24LC21T/SN
- Part No.:
- 24LC21T/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
24LC21T/SN.pdf
- Description:
- IC EEPROM 1KBIT I2C 400KHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,945
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
24LC21T/SN from Microchip Technology Inc. is a 128 × 8-bit I²C-compatible serial EEPROM designed for monitor identification and configuration storage in DDC1/DDC2-compliant display systems. It operates from 2.5V to 5.5V, supports dual-mode operation (Transmit-only and Bidirectional), delivers 1 mA active current, and ensures 1,000,000 erase/write cycles with >200 years data retention.
For engineers reviewing the 24LC21T/SN datasheet, 24LC21T/SN pinout, 24LC21T/SN application, or 24LC21T/SN equivalent, this device requires attention to VCLK/SCL mode selection logic, page-write buffer limits (8 bytes), write-protection via VCLK level, I²C timing compliance at 100 kHz (2.5V) and 400 kHz (5V), and its fixed 8-pin SOIC package with NC pins.
Technical Context
The 24LC21T/SN implements two distinct operational modes: Transmit-only mode uses VCLK as clock input and SDA as unidirectional output for continuous memory streaming, while Bidirectional mode uses SCL for clocking and SDA for full I²C read/write communication. Mode transition occurs only on a valid high-to-low edge on SCL; returning to Transmit-only requires power cycle.
Its internal architecture includes an EEPROM array, page latches, X/Y decoders, sense amplifiers, and dedicated control logic for auto-erase and self-timed write cycles. The device integrates Schmitt-trigger inputs on SCL/SDA with 50 ns spike suppression and a VCC threshold detector disabling programming below 1.5 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 128 × 8-bit (1 Kbit) - fixed address space supporting byte- and page-write operations |
| Supply voltage | 2.5V to 5.5V - enables direct interface with 3.3V and 5V systems without level shifting |
| I²C speed | 100 kHz at 2.5V / 400 kHz at 5V - defines maximum bus throughput and timing margin requirements |
| Write endurance | 1,000,000 cycles - guarantees long-term reliability in frequent configuration update scenarios |
| Data retention | >200 years - ensures nonvolatile storage integrity across product lifetime without refresh |
| Active current | 1 mA typical at 5.5V - determines power budget impact during memory access in active systems |
| Standby current | 10 µA typical at 5.5V - critical for low-power display subsystems during sleep or idle states |
Pinout & Package
24LC21T/SN is supplied in an 8-pin narrow SOIC package (JEDEC MS-012, body width 150 mil), with pin 1 marked by notch or bevel. Pins 1–3 and 6–8 are no-connect (NC); functional terminals occupy pins 4 (VSS), 5 (VCC), 7 (SCL), and 8 (SDA), while VCLK is assigned to pin 6 - confirmed per DS21095K-page 14 pin function table and SOIC outline drawing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VSS (Pin 4) | Ground reference | Return path for all internal circuitry; must be low-impedance connection to system GND plane |
| VCC (Pin 5) | Power supply | Supplies core logic and EEPROM array; requires local 0.1 µF bypass capacitor near pin |
| SCL (Pin 7) | Bidirectional mode clock | Master-generated clock for I²C transactions; also triggers mode switch from Transmit-only to Bidirectional |
| SDA (Pin 8) | Serial data I/O | Open-drain bidirectional bus line requiring external pull-up (2 kΩ for 400 kHz, 10 kΩ for 100 kHz) |
| VCLK (Pin 6) | Transmit-only clock / Write-enable | Clocks data output in Transmit-only mode; must be held high to enable writes in Bidirectional mode |
Key Features
| Feature | Design Value |
|---|---|
| Dual operational modes | Transmit-only mode streams full memory continuously via VCLK/SDA; Bidirectional mode enables selective byte/page reads/writes via standard I²C protocol |
| DDC1/DDC2 compliance | Fully implements Display Data Channel standards for EDID transmission in PC monitors and graphics adapters |
| Page-write buffer | 8-byte internal latch enables burst writes within single physical page boundary, reducing bus overhead vs. byte-write |
| VCLK-based write protection | Logic-low VCLK disables all write operations - allows hardware-level ROM emulation without firmware changes |
| Noise-immune interface | Schmitt-trigger inputs + 50 ns spike suppression on SCL/SDA ensure robust operation on electrically noisy display interconnects |
Applications
| Monitor EDID Storage | Display Configuration Memory |
|---|---|
Use Scenario: Storing Extended Display Identification Data (EDID) in LCD/LED monitors for plug-and-play detection by host GPUs. IC Role / Device Role / Timing Role: Serial EEPROM providing standardized 128-byte EDID block accessible via DDC2B I²C interface at 100 kHz. Use Value: Enables automatic resolution, timing, and color profile negotiation without user intervention or driver updates. | Use Scenario: Retaining user-adjusted brightness, contrast, and color temperature settings across power cycles in digital signage displays. IC Role / Device Role / Timing Role: Nonvolatile configuration store accessed during boot via I²C; retains values for >200 years without backup power. Use Value: Eliminates need for supercapacitors or batteries while ensuring consistent visual calibration after field deployment. |
| KVM Switch Firmware Table | Embedded Graphics Controller Setup |
Use Scenario: Holding port mapping tables and hotkey profiles in enterprise-grade KVM switches supporting multiple video sources. IC Role / Device Role / Timing Role: Dual-mode EEPROM: transmits default EDID on power-up (Transmit-only), then accepts dynamic updates via I²C (Bidirectional). Use Value: Allows seamless source switching without display retraining delays or blank screen artifacts. | Use Scenario: Storing gamma correction LUTs and panel timing parameters in industrial HMIs with integrated display controllers. IC Role / Device Role / Timing Role: High-reliability configuration memory rated for -40°C to +85°C operation and 1M write cycles. Use Value: Supports field-upgradable display tuning while meeting extended temperature and longevity requirements of factory automation equipment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 24LCS21A-I/SN | Successor part with identical pinout, enhanced ESD rating (8 kV HBM), and improved AC timing margins; supports same 128×8 capacity and dual-mode operation. | Recommended for new designs per Microchip notice; maintains full backward compatibility in existing layouts. | Select 24LCS21A-I/SN when designing new systems requiring longer product lifecycle support and higher noise immunity. |
| AT24C01C-SSHM-T | 1-Kbit I²C EEPROM with standard single-mode I²C interface (no VCLK or Transmit-only mode); 1 MHz max clock, 1M endurance, 10 µA standby. | Lacks DDC-specific Transmit-only streaming capability; requires host MCU to manage all read/write sequences. | Choose AT24C01C-SSHM-T where simplified firmware control is preferred and EDID streaming is not required. |
Compared with 24LC21T/SN, the 24LCS21A-I/SN offers drop-in replacement with enhanced robustness, while the AT24C01C-SSHM-T trades dual-mode flexibility for broader I²C ecosystem compatibility and higher speed - both require validation of VCLK-dependent functionality removal.
Availability
24LC21T/SN is available at Aetrix Electronics and suitable for monitor identification, display configuration storage, and embedded graphics controller setup requiring stable component supply across industrial temperature ranges (-40°C to +85°C).
Supply support for 24LC21T/SN 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 microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 24LC21T/SN belongs to Microchip's legacy serial EEPROM family engineered specifically for DDC-compliant display interfaces, emphasizing low-voltage operation, dual-mode flexibility, and long-term data integrity in visual subsystems.
FAQ
What is the primary function of the VCLK pin on the 24LC21T/SN?
The VCLK pin serves two distinct functions depending on operational mode: in Transmit-only mode, it acts as the clock input that synchronizes serial data output on SDA; in Bidirectional mode, it functions as a write-enable control - held high to permit writes, low to disable all programming. This dual role is fundamental to the 24LC21T/SN architecture and differentiates it from standard I²C EEPROMs.
Does the 24LC21T/SN support standard I²C addressing and protocol?
Yes, the 24LC21T/SN supports standard I²C addressing with a fixed 7-bit device code of '1010' followed by three don't-care bits, enabling R/W selection via the eighth bit. It complies with I²C timing specifications at 100 kHz (2.5V) and 400 kHz (5V), including Start/Stop conditions, ACK polling, and sequential/random read protocols - all verified in DS21095K AC characteristics tables.
How does the 24LC21T/SN handle page boundaries during write operations?
The 24LC21T/SN implements an 8-byte page buffer, and page writes are restricted to addresses within a single physical page. If a page write crosses a boundary (e.g., writing 8 bytes starting at address 0x07), data wraps to the start of the same page instead of advancing to the next. This behavior is explicitly documented in DS21095K-page 8 and requires firmware to align writes or split operations - a key constraint when using 24LC21T/SN in memory-intensive applications.
What is the significance of the "T" suffix in 24LC21T/SN?
The "T" in 24LC21T/SN denotes tape-and-reel packaging format per Microchip's ordering nomenclature, indicating the device is supplied on carrier tape compatible with automated SMT placement equipment. The "/SN" suffix specifies the 8-pin narrow SOIC package (MS-012), distinguishing it from PDIP (e.g., /P) or other variants - both identifiers are confirmed in DS21095K-page 14 packaging section.
Why does the 24LC21T/SN have three NC pins in its 8-pin SOIC package?
The 24LC21T/SN uses a shared 8-pin SOIC footprint with other members of the 24LCxx family, reserving pins 1–3 and pin 6 (VCLK) for functional expansion or variant differentiation. In this specific device, pins 1, 2, and 3 are designated NC per DS21095K-page 14 pin function table - a deliberate mechanical and routing simplification that maintains PCB layout compatibility across Microchip's serial EEPROM portfolio without altering electrical functionality of the 24LC21T/SN.
24LC21T/SN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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:
- 400 kHz
- Write Cycle Time - Word, Page:
- 10ms
- Access Time:
- 900 ns
- Voltage - Supply:
- 2.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
24LC21T/SN FAQ
1.How can I place an order for 24LC21T/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 24LC21T/SN 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 24LC21T/SN reliable?
The price and inventory of 24LC21T/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 24LC21T/SN is usually 5 days.
3.What payment methods are accepted for 24LC21T/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 24LC21T/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 24LC21T/SN?
24LC21T/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 24LC21T/SN 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 24LC21T/SN?
For technical support, including 24LC21T/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 24LC21T/SN requirements.
6.How does Aetrix verify that 24LC21T/SN is sourced from the original manufacturer or authorized distributors?
All 24LC21T/SN 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 24LC21T/SN meets industry standards.
7.What is the process for return or replacement of 24LC21T/SN?
All 24LC21T/SN units undergo pre-shipment inspection (PSI). If there is an issue with 24LC21T/SN, 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 24LC21T/SN part is unused and in its original packaging.
Return procedure for 24LC21T/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
24LC21T/SN Tags
-
M24C02-WMN6TP
STMicroelectronics
-
AT24C02C-XHM-T
Microchip Technology
-
AT21CS01-STUM10-T
Microchip Technology
-
AT24C02C-SSHM-T
Microchip Technology
-
24LC01BT-I/OT
Microchip Technology
-
M24C02-FMC6TG
STMicroelectronics
-
AT24CS02-SSHM-T
Microchip Technology
-
93LC46BT-I/OT
Microchip Technology
-
AT24C04C-SSHM-T
Microchip Technology
-
24LC01BT-I/SN
Microchip Technology
-
24AA02UIDT-I/OT
Microchip Technology
-
AT24C08C-STUM-T
Microchip Technology
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
