The ST25TB512-AC is a contactless memory, powered by an externally transmitted radio wave. It contains a 512-bit user EEPROM. The memory is organized as 16 blocks of 32 bits. The ST25TB512-AC is accessed via the 13.56 MHz carrier. Incoming data are demodulated and decoded from the received amplitude shift keying (ASK) modulation signal and outgoing data are generated by load variation using bit phase shift keying (BPSK) coding of a 847 kHz sub-carrier. The received ASK wave is 10% modulated. The data transfer rate between the ST25TB512-AC and the reader is 106 kbit/s in both reception and emission modes.
The ST25TB512-AC follows the ISO 14443 - 2 Type B recommendation for the radio-frequency power and signal interface.
The ST25TB512-AC is specifically designed for short range applications that need re-usable products. The ST25TB512-AC includes an anticollision mechanism that allows it to detect and select tags present at the same time within range of the reader. The anticollision is based on a probabilistic scanning method using slot markers.
The ST25TB512-AC contact-less EEPROM can be randomly read and written in block mode (each block containing 32 bits). The instruction set includes the following nine commands:
The ST25TB512-AC memory is organized in three areas, as described in Table 1. The first area is an resettable OTP (one time programmable) area in which bits can only be switched from 1 to 0. Using a special command, it is possible to erase all bits of this area to 1. The second area provides two 32-bit binary counters which can only be decremented. The last area is the EEPROM memory. It is accessible by block of 32 bits and includes an auto-erase cycle during each Write_block command.
Die floor plan and physical options related to the die assembly are described in Figure 2.
For the option 1 of the die assembly, the CTUN (referenced in RF electrical parameters) can increase from 0.5 pF to 1 pF. The option 2 of the die assembly is showing a tripod which can be used for physical stability, having no impact on CTUN parameter.
- ISO 14443-2 Type B air interface compliant
- ISO 14443-3 Type B frame format compliant
- 13.56 MHz carrier frequency
- 847 kHz subcarrier frequency
- 106 Kbit/second data transfer
- 8 bit Chip_ID based anticollision system
- 2 count-down binary counters with automated anti-tearing protection
- 64-bit Unique Identifier
- 512-bit EEPROM with write protect feature
- Read_block and Write_block (32 bits)
- Internal tuning capacitor: 68 pF
- 1 million erase/write cycles
- 40-year data retention
- Self-timed programming cycle
- 5 ms typical programming time
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