1Kb Protected 1-Wire EEPROM with SHA-1 Engine

The DS2432 combines 1024 bits of EEPROM, a 64-bit secret, an 8-byte register/control page with up to five user read/write bytes, a 512-bit SHA-1 engine, and a fully-featured 1-Wire interface in a single chip. Each DS2432 has its own 64-bit ROM registration number that is factory lasered into the chip to provide a guaranteed unique identity for absolute traceability. Data is transferred serially via the 1-Wire protocol, which requires only a single data lead and a ground return. The DS2432 has an additional memory area called the scratchpad that acts as a buffer when writing to the main memory, the register page or when installing a new secret. Data is first written to the scratchpad from where it can be read back. After the data has been verified, a copy scratchpad command will transfer the data to its final memory location, provided that the DS2432 receives a matching 160-Bit MAC. The computation of the MAC involves the secret and additional data stored in the DS2432 including the device's registration number. Only a new secret can be loaded without providing a MAC. The SHA-1 engine can also be activated to compute 160-bit message authentication codes (MAC) when reading a memory page or to compute a new secret, instead of loading it. Applications of the DS2432 include intellectual property security, after-market management of consumables, and tamper-proof data carriers.

Applications

* Device Authentication * IEEE 1451.4 Sensor TEDS * Ink/Toner Cartridges * Medical Sensors * PCB Identification * Self-Configuration of Central Office Switches, Wireless Base Stations, PBXs, or other Modular-Based Rack Systems

* 1128 Bits of 5V EEPROM Memory Partitioned Into Four Pages of 256 Bits, a 64-Bit Write-Only Secret, and Up to Five General-Purpose Read/Write Registers

* On-Chip 512-Bit ISO/IEC 10118-3 SHA-1 Engine to Compute 160-Bit Message Authentication Codes (MACs) and to Generate Secrets

* Write Access Requires Knowledge of the Secret and the Capability of Computing and Transmitting a 160-Bit MAC as Authorization

* Secret and Data Memory Can Be Write Protected (All or Page 0 Only) or Put in EPROM-Emulation Mode ("Write to 0", Page 1)

* Unique, Factory-Lasered and Tested 64-Bit Registration Number Assures Absolute Traceability Because No Two Parts Are Alike

* Built-In Multidrop Controller Ensures Compatibility with Other 1-Wire® Net Products

* Reduces Control, Address, Data, and Power to a Single Data Pin

* Directly Connects to a Single Port Pin of a Microprocessor and Communicates at Up to 15.3kbps

* Overdrive Mode Boosts Communication Speed to 90.9kbps

* Low-Cost 6-Lead TSOC Surface-Mount Package or Solder-Bumped UCSP™ Package

* Reads and Writes Over a Wide Voltage Range of 2.8V to 5.25V from -40°C to +85°C