ST1305

The ST1305 is a 192-bit EEPROM device with associated security logic to control memory access. The circuit includes counting capabilities and thus is very well adapted to prepaid card applications.

The ST1305 is protected by hard-wired security logic and special fuses. The memory is arranged as a matrix of 24x8 cells, accessed in a serial bit-wise fashion for reading and programming, and in a byte-wise fashion for internal erasing.

The device recognises three commands issued via the RST and CLK pins (as described in the full data sheet):
RESET: to reset the internal address register to 00d
READ: to increment the internal address register, and read the data bit at that address
PROG: to program the bit at the current address.

The ST1305 offers two distinct configurations:
ISSUER: for the card manufacturer, allowing special data to be written to the chip, during initialisation
USER: for the end user of the card, restricting access to the chip.

Before delivery, from ST to the card issuer, the ST1305 is placed in the ISSUER configuration. This operation is performed by blowing the "test fuse".