DESCRIPTION
IS23SC4418
IS23SC4418 contains 1024 x 8 bits of EEPROM with programmable write protection for each byte. Random read access to any byte in the memory is always possible. The memory can also be erased and written byte by byte. Erasing old data in the byte location must be performed before new data can be written to the location. Each byte in the memory has a corresponding protect bit. The protect bits are only one-time programmable and cannot be erased. After the protect bits are enabled (logic 0), the corresponding bytes can never be changed again. A write-protect bit with data-compare function is available for user to verify the datain the memory before enabling the protect bit.

IS23SC4428
IS23SC4428 offers all the features in IS23SC4418. In addition, it offers two bytes of Programmable Security Code (PSC) against unauthorized memory write/erase operations. All the memory, except for the PSC can always be read, but the memory can be written or erased only after PSC verification. If the user fails to enter the correct PSC in eight consecutive attempts, the device will block any further PSC entry attempts and the memory can never be erased or written again.

FEATURES
• Standard CMOS process
• 1024 x 8 bits EEPROM organization
• Byte-wise addressing
• Byte-wise erase/write
• Irreversible byte-wise write protection
• Single 5V power supply for read and write/erase
• Low power operation:
    – 3 mA typical active current
• 5 ms programming time
• 3-wire serial interface
• 20 KHz serial clock rate
• Contact configuration and serial interface, ISO standard 7816 (Synchronous Transmission) compatible.
• High ESD protection: > 4 KV
• High reliability:
    – 1,000,000 erase/write cycles guaranteed
    – 10 years data retention
• Wide operating temperature range
    – 0 to +70°C Commercial; –40 to +85°C Industrial

Additional feature of IS23SC4428:
• 2-byte Programmable Security Code (PSC) for memory write/erase protection