| SLE 4442 Memory Card
SLE 4442 contains 256 x 8 bits of EEPROM main memory and a 32 x 1 bit protection PROM memory. The main memory can be randomly accessed byte by byte. During memory erase, all 8 bits of a byte are set to logical one. During memory write, individual bit(s) are set to logical zeros depend on the data value to be written. Normally, a data change may consists of an erase and a write operation. The write or erase operation takes at least 2.5 ms to complete. The first 32 bytes (Address: 0 to 31) in memory are irreversibly protected by the corresponding 32 protect bits in the 32 x 1 bit protection memory.The 32 protect bits are onetime programmable, and they cannot be erased once they are set to logical zero. IS23SC4442 provides a 3-bit Error Counter (EC), and three bytes Programmable Security Code (PSC) to prevent unauthorized erase/write operation to the memory. All the memory, except the PSC, can be read after the chip is powered on. But, the memory can be written or erased only after the PSC is entered and verified correct. After three successive unsuccessful verifications of PSC, the Error Counter locks the chip from a further attempt, and the memory can never be erased or written. |
The SLE-4442 Secure Memory Card is one of the most popular "Smart Memory Cards" in the world. This chip includes an intelligent 256-Byte EEPROM with Write Protect Function and Programmable Security Code (PSC). This chip contains and EEPROM organized 1024 x 8 bit offering the possibility of programmable write protection for each byte. Reading of the whole memory is always possible. The memory can be written and erased byte by byte.
Standard CMOS process |
256 x 8 bits EEPROM organization > |
Byte-wise addressing |
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Irreversible byte-wise write protection of lowest: |
– 32 address (Byte 0..31) |
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3-byte Programmable Security Code (PSC) for |
– memory write/erase protection |
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Single 5V power supply for read and write/erase |
Low power operation: 3 mA typical active current |
2.5 ms programming time |
2-wire serial interface |
End of processing indication |
ISO standard 7816 compatible |
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High reliability: |
– 1,000,000 erase/write cycles guaranteed |
– 10 years data retention |
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Wide operating temperature range |
– 0oC to 70oC Commercial |
