Microchip Technology TK5551M-PP

Overview

TK5551M-PP from Atmel is a fully integrated 125 kHz contactless read/write RFID transponder in plastic package, embedding the e5551 IDIC, tuned LC antenna (3.8 mH coil + capacitor), and 264-bit EEPROM organized in eight 33-bit blocks. It supports anti-collision via password-request (AOR) mode, Manchester/FSK/PSK/Bi-phase modulation, and RF/32 bit rate by default - enabling <500 ms identification of up to 10 tags in access control systems.

For engineers reviewing the TK5551M-PP datasheet, TK5551M-PP pinout, TK5551M-PP application, or TK5551M-PP equivalent, key selection considerations include its self-contained LC antenna, lock-bit write protection, 10-year EEPROM data retention, 100,000 programming cycles, and field-powered operation requiring no onboard battery or external power supply.

Technical Context

The TK5551M-PP implements a closed-coupled RFID system where power and bidirectional data transfer occur via amplitude modulation of a 125 kHz RF field. Its analog front end includes a POR circuit, HV generator, and modulator tied directly to the integrated coil terminals - eliminating need for external matching components.

Communication uses gap-based encoding: valid '0' = 16–32 field clock cycles; valid '1' = 48 or 64 cycles. Block-wise read/write is controlled by an on-chip controller with dedicated mode register (Block 0) and password block (Block 7), supporting configurable bit rates (RF/8 to RF/128) and modulation schemes without firmware changes.

Key Specifications

Pinout & Package

TK5551M-PP is a monolithic plastic cube transponder with no external pins or terminals - the integrated coil forms both power harvesting and bidirectional communication interface. The device contains no user-accessible leads; electrical connection occurs solely via magnetic coupling to a reader's antenna coil.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RFID transponder applications.

Compared with TK5551M-PP, TK5550M-PP sacrifices configurability for guaranteed FSK compatibility, while EM4102 eliminates write functionality entirely - making TK5551M-PP the only option supporting secure, field-updatable, multi-tag identification in industrial environments.

Availability

TK5551M-PP is available at Aetrix Electronics and suitable for access control systems, asset tracking solutions, and industrial automation equipment requiring stable component supply, long-term data integrity, and field-programmable identity management.

Supply support for TK5551M-PP 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

Atmel Corporation (now part of Microchip Technology) is a semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and RFID solutions for industrial, automotive, and secure identification markets.

The TK5551M-PP belongs to Atmel's contactless ID transponder product line, designed specifically for closed-coupled 125 kHz RFID systems requiring embedded antenna, EEPROM programmability, and anti-collision support in harsh environments.

FAQ

What is the operating frequency and resonance tolerance of the TK5551M-PP?

The TK5551M-PP operates at a nominal carrier frequency of 125 kHz, with a measured resonance range of 120–130 kHz at room temperature. Its integrated LC circuit - comprising a 3.8 mH ferrite-core coil and tuning capacitor - is factory-trimmed to this band, ensuring reliable coupling with standard U2270B-based readers without external tuning. Temperature drift is characterized at ±4% over −40 °C to +85 °C.

Does the TK5551M-PP require an external power source or battery?

No, the TK5551M-PP is fully field-powered: it derives all operating energy from the magnetic field generated by the reader's antenna at 125 kHz. Its internal analog front end rectifies and regulates this induced voltage to power the e5551 IC and EEPROM - eliminating batteries, wiring, or maintenance. This enables truly passive, embeddable deployment in sealed or rotating assets.

How many times can the EEPROM in the TK5551M-PP be rewritten, and what is its data retention?

The TK5551M-PP features 264-bit EEPROM rated for 100,000 write/verify cycles and guaranteed 10-year data retention at 25 °C. Each of the eight 33-bit blocks can be independently locked using on-chip lock bits, and Block 7 stores a user-defined password to prevent unauthorized writes - making it suitable for applications requiring frequent, secure updates over extended service life.

What anti-collision method does the TK5551M-PP support, and how many tags can it handle?

The TK5551M-PP implements Answer-On-Request (AOR) anti-collision, where tags remain in sleep mode until individually addressed with a 32-bit password. In lab conditions using RF/32 bit rate and MAXBLK = 2, up to 10 transponders can be uniquely identified and read within 500 ms. Performance scales with reader field strength and modulation choice - confirmed in Atmel's Rev. 4709B characterization.

Can the TK5551M-PP be reprogrammed in the field, and what interfaces are required?

Yes, the TK5551M-PP supports full field reprogramming of its EEPROM via contactless RF interface - no physical connection needed. Reprogramming requires a compatible 125 kHz reader (e.g., based on U2270B or discrete designs) capable of sending gap-encoded commands. All configuration - including bit rate, modulation, lock bits, and password - is stored in on-chip EEPROM and persists through power cycles. The TK5551M-PP itself has no pins or debug interface.