Introduction
The following sections introduce the features and functions of the Microchip ATSHA204A crypto element device.

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)
• 4.5 kb 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
   – 1 MHz I2C Interface
• 2.0V to 5.5V Supply Voltage Range
• 1.8V to 5.5V Communications Voltage Range
• <150 nA 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 and
   3-lead CONTACT Packages

APPLICATIONs
• Secure Download and Boot
• Ecosystem Control
• Anti-cloning
• Message Security