iButton 1024-Bit EEPROM

The iButton® 256-bit EEPROM (DS1972) is a 1024-bit, 1-Wire® EEPROM chip in a rugged iButton package. Data is written to an 8-byte scratchpad, verified, and then copied to the EEPROM memory. As a special feature, the four memory pages can individually be write protected or put in EPROM-emulation mode, where bits can only be changed from a 1 to a 0 state. The DS1972 communicates over the single-conductor 1-Wire bus. The communication follows the standard 1-Wire protocol. Each device has its own unalterable and unique 64-bit ROM registration number that is factory lasered into the device. The registration number is used to address the device in a multidrop, 1-Wire net environment.

Applications

* Access Control/Parking Meter * Inventory Control * Maintenance/Inspection Data Storage * Tool Management * Work-in-Progress Tracking

* 1024 Bits of EEPROM Memory Partitioned into Four Pages of 256 Bits

* Individual Memory Pages can be Permanently Write Protected or Put in EPROM-Emulation Mode ("Write to 0")

* Switchpoint Hysteresis and Filtering to Optimize Performance in the Presence of Noise

* IEC 1000-4-2 Level 4 ESD Protection (±8kV Contact, ±15kV Air, typical)

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

* Communicates to Host with a Single Digital Signal at 15.4kbps or 125kbps Using 1-Wire Protocol