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Microchip Technology 24LCS21A-I/SN
- Part No.:
- 24LCS21A-I/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
24LCS21A-I/SN.pdf
- Description:
- IC EEPROM 1KBIT I2C 400KHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,803
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Product details
Overview
24LCS21A-I/SN from Microchip Technology Inc. is a 128 × 8-bit dual-mode I²C™-compatible serial EEPROM designed for monitor configuration storage and DDC1™/DDC2™ compliance. It operates from 2.5V to 5.5V, supports Transmit-Only (VCLK-clocked) and Bidirectional (SCL-clocked) modes, features hardware write-protection via WP pin, and delivers 1 mA active current with 10 μA standby current at 5.5V. It is used in display identification circuits for EDID™ data transmission.
For engineers reviewing the 24LCS21A-I/SN datasheet, 24LCS21A-I/SN pinout, 24LCS21A-I/SN application, or 24LCS21A-I/SN equivalent, key selection considerations include dual-mode clocking (VCLK vs. SCL), flexible write-protection logic (WP + VCLK interaction), guaranteed 1 million erase/write cycles, 200-year data retention, and industrial-temperature SOIC-8 packaging.
Technical Context
The 24LCS21A-I/SN implements two independent communication protocols on shared SDA: Transmit-Only mode uses VCLK as clock input and outputs EDID™ bitstream continuously from address 00h to 7Fh, while Bidirectional mode uses SCL for I²C™-compliant read/write access with slave address 1010000X. Mode transition occurs only on valid high-to-low SCL edge followed by detection of control byte '1010000X'.
Write protection is implemented through dual mechanisms: factory-default unlocked operation (VCLK = high enables writes), and optional fuse-based locking enabled by writing any value to address 7Fh - after which both WP (active-low) and VCLK (high required) jointly govern write capability per Table 6-1. Internal address pointer auto-increments during sequential reads and page writes.
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 and modern low-voltage display interfaces |
| Operating modes | Transmit-Only (VCLK-driven, unidirectional EDID™ streaming) and Bidirectional (I²C™ slave, address 0xA0/A01) |
| Write endurance | 1,000,000 erase/write cycles - ensures long-term reliability in field-updatable display systems |
| Data retention | >200 years at 25°C - eliminates need for periodic refresh in permanently installed monitors |
| I²C™ speed | 100 kHz (2.5V) / 400 kHz (5V) - compatible with standard and fast-mode I²C™ masters |
| Write protection | Hardware-enabled via WP pin and VCLK level, configurable via fuse at address 7Fh |
Pinout & Package
24LCS21A-I/SN is housed in an 8-pin plastic SOIC (150 mil body) package, RoHS-compliant and rated for -40°C to +85°C industrial temperature range.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (NC) | No Connection | Unbonded pin; must be left floating or tied to GND/VCC per board layout rules |
| 2 (NC) | No Connection | Unbonded pin; no electrical function; avoid routing signals nearby |
| 3 (WP) | Write-Protect Input | Active-low enable: when fuse set (address 7Fh written), WP = low disables all writes regardless of VCLK |
| 4 (VSS) | Ground | Reference return path for all internal circuitry and I/O pins |
| 5 (VCC) | Power Supply | 2.5V–5.5V supply input; includes internal VCC threshold detector disabling writes below ~1.5V |
| 6 (VCLK) | Transmit-Only Clock / Write Enable | In Transmit-Only mode: rising edge clocks EDID™ bitstream; in Bidirectional mode: high level required to permit writes |
| 7 (SCL) | Bidirectional Clock Input | I²C™ clock input; high-to-low transition triggers mode transition from Transmit-Only to Bidirectional |
| 8 (SDA) | Serial Data I/O | Open-drain bidirectional bus line; requires external pull-up (1 kΩ @ 400 kHz, 10 kΩ @ 100 kHz) |
Key Features
| Feature | Design Value |
|---|---|
| Dual-mode operation | Enables seamless integration into both legacy DDC1™ (VCLK-clocked) and modern DDC2™ (I²C™) display systems without firmware change |
| Self-timed write cycle | Eliminates need for external timing control; internal auto-erase and programming complete within 10 ms max |
| Page write buffer | Accepts up to eight bytes before initiating internal write - reduces bus occupancy and improves update efficiency |
| ESD protection | >4000V HBM - robust enough for handling during monitor assembly and field service |
| Flexible write protection | Configurable lock: factory-unlocked (VCLK-only control) or fused (WP + VCLK joint control), supporting both ROM-like and field-programmable use cases |
Applications
| Monitor EDID™ Storage | Display Configuration Memory |
|---|---|
Use Scenario: Storing Extended Display Identification Data (EDID™) in LCD, LED, or OLED monitors for plug-and-play compatibility with host GPUs. IC Role / Device Role / Timing Role: Primary nonvolatile memory holding standardized display capabilities (resolution, timing, vendor ID); operates in Transmit-Only mode synchronized to VSYNC-derived VCLK. Use Value: Enables automatic display enumeration and optimal resolution negotiation without host driver intervention. | Use Scenario: Retaining user-adjusted settings (brightness, contrast, color profile) across power cycles in digital signage and medical displays. IC Role / Device Role / Timing Role: Bidirectional I²C™ slave storing configuration parameters; accessed by display controller MCU during boot or menu navigation. Use Value: Preserves calibrated settings with guaranteed 200-year retention and 1M-cycle endurance for frequent updates. |
| DDC2™ Compliance Interface | Industrial Panel PC Configuration |
Use Scenario: Supporting dynamic DDC2™ communication for real-time brightness/contrast adjustment via GPU or OS-level controls. IC Role / Device Role / Timing Role: I²C™ slave responding to master requests at address 0xA0 (write) / 0xA1 (read); transitions from Transmit-Only to Bidirectional mode on SCL edge. Use Value: Allows runtime reconfiguration without requiring display power cycle or physical reset. | Use Scenario: Storing calibration coefficients, firmware version flags, and hardware revision IDs in ruggedized panel PCs for factory diagnostics and field maintenance. IC Role / Device Role / Timing Role: Industrial-grade serial EEPROM interfacing with ARM Cortex-M host MCU over I²C™; operates reliably from -40°C to +85°C. Use Value: Ensures traceability and configuration integrity in harsh environments where commercial-grade EEPROMs may fail. |
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 | 2-Kbit capacity, single I²C™ mode only (no Transmit-Only/VCLK support), 1 MHz max clock | Lacks DDC1™ compatibility; cannot replace 24LCS21A-I/SN in legacy monitor designs requiring VCLK-clocked EDID™ streaming | Select only if system uses pure I²C™ configuration and does not require DDC1™ compliance or VCLK interface. |
| 24LC024T-I/SN | 2-Kbit capacity, I²C™-only, same SOIC-8 package and industrial temp range, but no VCLK pin or dual-mode logic | Cannot emulate Transmit-Only behavior; unsuitable for EDID™ streaming without external clock generation logic | Choose when higher density is needed and DDC1™ functionality is absent from the target design. |
Compared with AT24C02C-SSHM-T and 24LC024T-I/SN, the 24LCS21A-I/SN uniquely integrates VCLK-driven EDID™ streaming and I²C™ bidirectional access in one device - eliminating need for external mode-switching logic or dual EEPROMs in display subsystems.
Availability
24LCS21A-I/SN is available at Aetrix Electronics and suitable for display identification, monitor configuration storage, EDID™ management, and industrial panel PC calibration requiring stable component supply across extended temperature ranges.
Supply support for 24LCS21A-I/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 manufacturer specializing in microcontrollers, analog devices, and memory products, with global design and manufacturing infrastructure.
The 24LCS21A-I/SN belongs to Microchip's dual-mode serial EEPROM product line, engineered specifically to meet VESA® DDC1™/DDC2™ standards for display interface compliance and seamless EDID™ implementation.
FAQ
What is the primary function of the VCLK pin on the 24LCS21A-I/SN?
The VCLK pin serves two distinct roles: in Transmit-Only mode, it acts as the clock input that synchronizes continuous EDID™ bitstream output on SDA; in Bidirectional mode, it functions as a write-enable control - writes are permitted only when VCLK is held high. This dual functionality enables the 24LCS21A-I/SN to operate in both legacy DDC1™ and modern DDC2™ systems without external logic.
How does write protection work on the 24LCS21A-I/SN?
Write protection on the 24LCS21A-I/SN is configurable: initially unlocked (VCLK = high enables writes), it becomes fuse-activated after any data is written to address 7Fh. Once fused, both WP (active-low) and VCLK (must be high) jointly determine write capability - if either condition fails, writes are blocked. This allows flexible deployment as field-programmable memory or locked-down ROM depending on system requirements.
Can the 24LCS21A-I/SN be used in place of a standard I²C™ EEPROM like the 24LC01B?
Yes, but only in Bidirectional mode - the 24LCS21A-I/SN responds to standard I²C™ commands at slave address 0xA0/0xA1 and supports byte/page writes and reads. However, it lacks direct pin-to-pin compatibility due to extra VCLK and NC pins, and its 1-Kbit capacity differs from 24LC01B's 128-byte size. System-level validation is required to confirm timing, pull-up, and mode initialization behavior.
What happens if the SCL pin receives a high-to-low transition while the 24LCS21A-I/SN is in Transmit-Only mode?
A valid high-to-low transition on SCL causes the 24LCS21A-I/SN to enter Transition mode and listen for its I²C™ control byte (1010000X). If detected, it switches permanently to Bidirectional mode until power is cycled. If no control byte arrives within 128 VCLK pulses, it automatically reverts to Transmit-Only mode. This mechanism enables on-demand mode switching without resetting the device.
Is the 24LCS21A-I/SN compatible with standard I²C™ bus speeds and timing requirements?
Yes - the 24LCS21A-I/SN meets standard-mode (100 kHz) timing at 2.5V–4.5V and fast-mode (400 kHz) timing at 4.5V–5.5V, including THIGH, TLOW, TSU:DAT, and TAA specifications. Its SDA and SCL inputs include Schmitt triggers and spike filters (50 ns), ensuring robust operation on noisy display interface buses without additional signal conditioning.
24LCS21A-I/SN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
24LCS21A-I/SN FAQ
1.How can I place an order for 24LCS21A-I/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 24LCS21A-I/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 24LCS21A-I/SN reliable?
The price and inventory of 24LCS21A-I/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 24LCS21A-I/SN is usually 5 days.
3.What payment methods are accepted for 24LCS21A-I/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 24LCS21A-I/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 24LCS21A-I/SN?
24LCS21A-I/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 24LCS21A-I/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 24LCS21A-I/SN?
For technical support, including 24LCS21A-I/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 24LCS21A-I/SN requirements.
6.How does Aetrix verify that 24LCS21A-I/SN is sourced from the original manufacturer or authorized distributors?
All 24LCS21A-I/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 24LCS21A-I/SN meets industry standards.
7.What is the process for return or replacement of 24LCS21A-I/SN?
All 24LCS21A-I/SN units undergo pre-shipment inspection (PSI). If there is an issue with 24LCS21A-I/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 24LCS21A-I/SN part is unused and in its original packaging.
Return procedure for 24LCS21A-I/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
24LCS21A-I/SN Tags
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