My Inquiry
My Account
Microchip Technology 24LCS21AT/SN
- Part No.:
- 24LCS21AT/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
24LCS21AT/SN.pdf
- Description:
- IC EEPROM 1KBIT I2C 400KHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,001
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
24LCS21AT/SN from Microchip Technology Inc. is a 128 × 8-bit dual-mode I²C™-compatible serial EEPROM designed for display configuration storage and DDC1/DDC2 monitor identification. It operates from 2.5V to 5.5V, supports both Transmit-Only (DDC1) and Bidirectional (I²C) modes, features hardware write-protection via WP pin, and delivers 1 mA active current with 10 μA standby current at 5.5V.
For engineers reviewing the 24LCS21AT/SN datasheet, 24LCS21AT/SN pinout, 24LCS21AT/SN application, or 24LCS21AT/SN equivalent, key selection considerations include its dual-clock architecture (VCLK for DDC1, SCL for I²C), flexible write-protection logic requiring address 7Fh programming to enable WP control, and guaranteed 1 million erase/write cycles with >200-year data retention.
Technical Context
The 24LCS21AT/SN implements two independent communication protocols sharing the SDA line: Transmit-Only mode uses VCLK as clock input and outputs EDID™ data continuously from address 00h to 7Fh, while Bidirectional mode uses SCL and responds to I²C slave address 1010000X. Mode transition occurs only on valid high-to-low SCL edge followed by detection of its control byte - and once entered, Bidirectional mode persists until power cycle.
Its internal architecture includes a page write buffer (8 bytes), Schmitt-trigger inputs on SDA/SCL/VCLK for noise immunity, VCC threshold detector disabling write logic below 1.5V, and dual write-protection layers: WP pin (enabled after writing any value to address 7Fh) and VCLK level (must be high for writes in Bidirectional mode). The device is not Access.bus™ capable and strictly complies with VESA DDC standards.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 128 × 8-bit (1 Kbit) EEPROM array, sufficient for full EDID block storage |
| Supply voltage | 2.5V to 5.5V - supports legacy 5V DDC buses and modern low-voltage systems |
| I²C speed | 100 kHz at 2.5V / 400 kHz at 5V - enables fast configuration reads during system boot |
| Write endurance | 1,000,000 erase/write cycles - ensures reliability across repeated display hot-plug events |
| Data retention | >200 years at 25°C - eliminates need for periodic refresh in embedded display firmware |
| ESD protection | >4000V HBM - robust against electrostatic discharge during panel assembly and field service |
| Operating temperature | −40°C to +85°C (Industrial grade) - qualified for use in commercial and industrial monitors |
Pinout & Package
24LCS21AT/SN is supplied in an 8-pin plastic SOIC (SN) package, 150 mil body width, surface-mount compatible with standard reflow profiles.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: NC | No Connection | Unbonded pad - must remain floating; no external connection required |
| 2: NC | No Connection | Unbonded pad - must remain floating; no external connection required |
| 3: WP | Write-Protect Input | Active-low control enabled only after writing to address 7Fh; determines R/W capability when combined with VCLK level |
| 4: VSS | Ground Reference | Primary return path for all internal circuitry and I/O drivers |
| 5: SDA | Serial Data I/O | Open-drain bidirectional bus line shared between both modes; requires external pull-up resistor |
| 6: SCL | I²C Clock Input | Triggers mode transition from Transmit-Only to Bidirectional; synchronizes all I²C read/write operations |
| 7: VCLK | DDC1 Clock Input | Drives bit output timing in Transmit-Only mode; must be held high to enable writes in Bidirectional mode |
| 8: VCC | Power Supply | 2.5–5.5V supply input; powers EEPROM core, logic, and I/O buffers |
Key Features
| Feature | Design Value |
|---|---|
| Dual-mode operation | Transmit-Only (DDC1) and Bidirectional (I²C) protocols coexist on single SDA line - eliminates need for separate EDID ROM and configuration EEPROM |
| Hardware write protection | Two-layer protection: WP pin (enabled post-7Fh write) and VCLK level requirement - prevents accidental overwrites during system initialization |
| Page write buffer | 8-byte internal latch enables burst writes without intermediate Stop conditions - reduces I²C bus occupancy during EDID updates |
| Self-timed write cycle | Automatic erase-and-program sequence completes in ≤10 ms - removes need for external timing control or polling overhead |
| Noise-immune inputs | Schmitt-trigger + 50 ns spike suppression on SDA/SCL/VCLK - ensures reliable operation on electrically noisy display interface buses |
Applications
| Monitor EDID Storage | Display Configuration Backup |
|---|---|
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: Primary nonvolatile memory holding standardized 128-byte EDID block; outputs data continuously on VCLK in Transmit-Only mode during DDC1 handshake. Use Value: Enables plug-and-play compatibility without host driver intervention; leverages guaranteed >200-year data retention to avoid EDID corruption over product lifetime. | Use Scenario: Preserving custom display settings (brightness, color profile, gamma) across power cycles in digital signage and kiosk displays. IC Role / Device Role / Timing Role: Slave EEPROM in I²C-based configuration management subsystem; accepts byte/page writes from MCU during user adjustment or factory calibration. Use Value: Supports 1M write cycles - withstands daily recalibration routines over 10+ years; page buffer accelerates multi-parameter save operations. |
| DDC2B Communication Interface | Industrial Panel PC Boot Configuration |
Use Scenario: Enabling bidirectional DDC2B commands between graphics controller and monitor for real-time brightness/contrast control and status reporting. IC Role / Device Role / Timing Role: I²C slave responding to address 1010000X; provides read/write access to extended configuration registers beyond base EDID. Use Value: Uses same physical device for both legacy DDC1 broadcast and modern DDC2B interactive control - reduces BOM count and PCB footprint. | Use Scenario: Storing boot-time video mode parameters (resolution, refresh rate, pixel clock) for headless industrial HMIs where GPU initialization must be deterministic. IC Role / Device Role / Timing Role: Early-boot configuration source accessed via I²C before OS loads; supplies validated timing parameters to display controller firmware. Use Value: Industrial temperature rating (−40°C to +85°C) ensures reliable parameter retrieval during cold-start in factory automation environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 24LC21A-I/SN | Same die, identical pinout and dual-mode functionality; differs only in tape/reel packaging (no 'T' suffix in part number) | No functional difference - used interchangeably where reel packaging is not required | Select 24LC21A-I/SN for manual or small-batch assembly; 24LCS21AT/SN preferred for automated SMT lines |
| AT24C01C-SSHM-T | Single-mode I²C EEPROM (no DDC1/Transmit-Only mode); 1Kbit capacity; 1 MHz max clock; no VCLK or mode-transition logic | Lacks DDC1 compliance - cannot replace 24LCS21AT/SN in monitor EDID applications requiring continuous transmit | Choose AT24C01C-SSHM-T only for general-purpose I²C configuration storage where DDC1 compatibility is unnecessary |
Compared with 24LCS21AT/SN, 24LC21A-I/SN offers identical electrical and functional behavior but lacks tape-and-reel packaging, while AT24C01C-SSHM-T provides higher-speed I²C operation but omits critical DDC1 support - making it unsuitable for monitor identification systems requiring unidirectional EDID broadcast.
Availability
24LCS21AT/SN is available at Aetrix Electronics and suitable for monitor EDID storage, display configuration backup, DDC2B communication interfaces, and industrial panel PC boot configuration requiring stable component supply across long production lifecycles.
Supply support for 24LCS21AT/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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and memory solutions for embedded control applications.
The 24LCS21AT/SN belongs to Microchip's dual-mode serial EEPROM product line, engineered specifically for VESA DDC-compliant display systems requiring both legacy DDC1 broadcast and modern DDC2B bidirectional communication in a single IC.
FAQ
What is the primary function of the VCLK pin on the 24LCS21AT/SN?
The VCLK pin serves as the clock input for Transmit-Only (DDC1) mode, driving bit output timing on the SDA line. In Bidirectional (I²C) mode, it acts as a write-enable control: writes are only permitted when VCLK is held high. The 24LCS21AT/SN will not accept writes if VCLK is low, regardless of WP pin state or I²C command validity.
How does write protection work on the 24LCS21AT/SN?
Write protection on the 24LCS21AT/SN uses two interdependent layers: first, writing any value to memory address 7Fh enables the WP pin; second, after enabling, the WP pin (active-low) and VCLK level jointly determine write capability per Table 6-1. Until address 7Fh is written, the 24LCS21AT/SN remains fully writable if VCLK = high - no WP pin action is required.
Can the 24LCS21AT/SN be used as a standard I²C EEPROM without DDC functionality?
Yes - the 24LCS21AT/SN operates as a fully compliant I²C EEPROM in Bidirectional mode using slave address 1010000X, supporting byte and page writes, random/sequential reads, and ACK polling. Its DDC1 Transmit-Only mode is disabled by default upon power-up only if SCL remains high; it does not interfere with standard I²C operation unless explicitly triggered.
What happens if a page write crosses a physical page boundary on the 24LCS21AT/SN?
If a page write command attempts to write across a physical page boundary (i.e., beyond address 7Fh when starting at 78h), data wraps around to the beginning of the current 8-byte page instead of advancing to the next page. This overwrites previously loaded data within that page. Application firmware must enforce page-aligned writes - the 24LCS21AT/SN does not auto-segment or buffer across boundaries.
Is the 24LCS21AT/SN RoHS compliant and lead-free?
Yes - the 24LCS21AT/SN is Pb-free and RoHS compliant per Microchip's DS21161H documentation. The SN package designation confirms it meets JEDEC standard J-STD-020 moisture sensitivity level (MSL) requirements for SOIC packages and is qualified for lead-free reflow soldering processes.
24LCS21AT/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
24LCS21AT/SN FAQ
1.How can I place an order for 24LCS21AT/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 24LCS21AT/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 24LCS21AT/SN reliable?
The price and inventory of 24LCS21AT/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 24LCS21AT/SN is usually 5 days.
3.What payment methods are accepted for 24LCS21AT/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 24LCS21AT/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 24LCS21AT/SN?
24LCS21AT/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 24LCS21AT/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 24LCS21AT/SN?
For technical support, including 24LCS21AT/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 24LCS21AT/SN requirements.
6.How does Aetrix verify that 24LCS21AT/SN is sourced from the original manufacturer or authorized distributors?
All 24LCS21AT/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 24LCS21AT/SN meets industry standards.
7.What is the process for return or replacement of 24LCS21AT/SN?
All 24LCS21AT/SN units undergo pre-shipment inspection (PSI). If there is an issue with 24LCS21AT/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 24LCS21AT/SN part is unused and in its original packaging.
Return procedure for 24LCS21AT/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
24LCS21AT/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…
