LX9910A

The LX9910A is a low-frequency 125 kHz read-only RFID transponder IC fully compatible with the EM4102 protocol, a de facto industry standard for contactless identification. Operating under ISO/IEC 18000-2, the chip uses inductive coupling to harvest energy from the reader's magnetic field, eliminating the need for a battery. The 64-bit memory structure is factory-programmed and organized as a header (9 bits), 40 bits of unique ID data (typically split into version/customer/data fields), and 24 parity bits for error detection. Data transmission employs Manchester encoding, which ensures clock recovery at the reader and provides robust decoding in noisy RF environments. The chip modulates the load on the coil to backscatter the ID using on-off keying (OOK), with data clocked at 64 periods per bit (RF/64). Because it conforms to the EM4102 read-only standard, the LX9910A supports no anti-collision; each tag must be read individually. The absence of encryption or write capability simplifies manufacturing and reduces cost, making it ideal for high-volume applications where tamper resistance is not required.

The LX9910A dominates animal identification deployments worldwide, embedded in glass transponders for subcutaneous pet tagging and livestock management. Its read-only architecture and long-term reliability suit veterinary clinics, farms, and animal shelters that require permanent, low-cost identification without power requirements. In access control, the chip is found in key fobs, proximity cards, and clamshell tags for basic building entry, parking gates, and gym access—particularly in legacy systems where security is secondary to convenience and cost. Asset tracking applications include industrial tool identification, container tagging, and laundry management, where read-only IDs are linked to back-end databases. The LX9910A ships in a variety of form factors: 2×12 mm and 3×13 mm glass ampoules for animal use, ISO card and key-fob housings for access control, and disk tags for asset labeling. Its wide operating temperature range (−40 °C to +85 °C) and compatibility with legacy EM4100 and EM4200 readers ensure seamless integration into existing infrastructure.

The LX9910A is factory-programmed only; end users and integrators cannot write or modify the 64-bit ID. The unique identifier is laser-etched during manufacturing and transmitted in a continuous stream when energized by a compliant 125 kHz reader. No command set exists—readers simply power the tag and decode the Manchester-encoded bitstream. The 64-bit payload is structured as 9 header bits (always 111111111), 10 rows of 4 data bits each (40 bits total), 10 column parity bits, and 4 row parity bits, followed by a stop bit. Integrators must ensure their reader firmware supports EM4102 demodulation and parity checking; most legacy Prox, HID, and generic 125 kHz readers are compatible. There is no read command—proximity alone triggers transmission. Common pitfalls include confusing the LX9910A with EM4450 or EM4550 read-write chips; attempting to write to the LX9910A will always fail. For systems requiring field-programmable IDs, consider the EM4205/EM4305 family. Reader antenna tuning and proper tag orientation (parallel to the reader coil plane) are critical for maximizing read range, typically 5–10 cm with standard antennas.

The LX9910A is widely available through EM Microelectronic authorized distributors and RFID inlay converters specializing in 125 kHz products. Major suppliers include Smartrac (now part of Avery Dennison), Omni-ID, and regional tag assemblers. For custom ID programming, buyers typically order pre-encoded chips or finished transponders directly from contract manufacturers; minimum order quantities range from 500 to 5,000 units depending on form factor and encoding complexity. Lead times are generally 4–8 weeks for custom-programmed glass tags and 2–4 weeks for standard card or fob assemblies. When specifying orders, confirm the desired ID format (decimal or hexadecimal), bit structure (customer code, version bits), and physical form factor. Cross-shop to the EM4100 for lower-cost read-only applications or the EM4102 for identical functionality with different packaging. For projects requiring cryptographic security or read-write capability, evaluate the EM4450 or migrate to HF platforms like MIFARE Classic 1K. Always request compatibility verification with your existing reader infrastructure before committing to volume orders.