The ATSHA204A device includes an Electrically Erasable Programmable Read-Only Memory (EEPROM) array that can be used for key storage, miscellaneous read/write data, read-only, secret data, consumption logging, and security configuration.
Access to the various sections of memory can be restricted in a variety of ways, and the configuration can then be locked to prevent changes.

Features
● Crypto Element with Protected Hardware-based Key Storage
● Secure Symmetric Authentication Device Host and Client Operations
● Superior SHA-256 Hash Algorithm with Message Authentication Code (MAC)
   and Hash-Based Message Authentication Code (HMAC) Options
● Best-in-class, 256-bit Key Length; Storage for Up to 16 Keys
● Guaranteed Unique 72-bit Serial Number
● Internal, High-quality Random Number Generator (RNG)
● 4.5Kb EEPROM for Keys and Data
● 512 bit OTP (One Time Programmable) Bits for Fixed Information
● Multiple I/O Options
   ̶ UART-compatible High-Speed, Single-Wire Interface
   ̶ 1MHz I2C Interface
● 2.0V to 5.5V Supply Voltage Range
● 1.8V to 5.5V Communications Voltage Range
● <150nA Sleep Current
● Secure Download and Boot
   ̶ Ecosystem Control
   ̶ Message Security
   ̶ Anti-Cloning
● 8-lead SOIC, 8-lead TSSOP(2), 3-lead SOT23, 8-pad UDFN, 8-pad XDFN, and
   3-lead CONTACT Packages

Applications
● Secure Download and Boot
● Ecosystem Control
● Anti-cloning
● Message Security