iButton 1024-Bit EEPROM

EPROM-Emulation Mode for Protection Against Accidental Erasure or Tampering of Data

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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.

Key Features

  • 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


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

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.
Product Reliability Reports: DS1972.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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