DS2423

· 4096 bits of SRAM
· Four 32-bit, read-only counters
· Active-low external trigger inputs for two of  the counters with on-chip debouncing compatible with reed and Wiegand switches
· Unique, factory-lasered and tested 64-bit registration number (8-bit family code + 48- bit serial number + 8-bit CRC tester) assures absolute traceability because no two parts are alike
· Memory partitioned into 16 256-bit pages in for packetizing data
· 256-bit scratchpad with strict read/write protocols ensures integrity of data transfer
· On-chip 16-bit CRC generator for safeguarding data transfers
· Built-in multidrop controller ensures compatibility with other MicroLAN products
· Directly connects to a single port pin of a microprocessor and communicates at up to 16.3kbits per second
· Overdrive mode boosts communication speed to 142kbits per second
· 8-bit family code specifies device communication requirements to reader
· Presence detector acknowledges when reader first applies voltage
· Compact, low cost 6-pin TSOC surface mount package
· Reads, writes and counts over a wide voltage range of 2.8V to 5.5V from -40°C to +85°C

Voltage on Any Pin Relative to Ground .....................-0.5V to +7.0V
Operating Temperature Range ...............................-40°C to +85°C
Storage Temperature Range ................................-55°C to +125°C
Soldering Temperature ....................See J-STD-020A Specifications

* This is a stress rating only and functional operation of the device at these or any other conditionsabove those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.

The DS2423 1-Wire^® RAM with Counters is a fully static, read/write memory for battery operation in a low-cost, six-lead TSOC, surface-mount package. The memory is organized as 16 pages of 256 bits each. In addition, the device has four counters, two of them with external trigger inputs called A and B. Each of the counters is associated with a memory page. A counter without external trigger input increments each time data is written to the page it is associated with (write cycle counter). The counters triggered by inputs A and B, respectively, increment with every low-going pulse on their input. All counters are readonly. They are automatically cleared to 0 when the battery is connected.

The battery-backed memory offers a simple solution to storing and retrieving information pertaining to the equipment where the DS2423 is installed and its frequency of use. The scratchpad is an additional page that acts as a buffer when writing to memory. Data is first written to the scratchpad where it may be read back for verification. A copy scratchpad command will then transfer the data to memory. This process ensures data integrity when modifying the memory. A 64-bit registration number is factory lasered into each DS2423 to provide a guaranteed unique identity which allows for absolute traceability and acts as node address if multiple DS2423 are connected in parallel to form a local network. Data is transferred serially via the 1-Wire protocol, which requires only a single data lead and a ground return.

The DS2423 1-Wire RAM with Counters can store encrypted data. The unique registration number and the page write cycle counter(s) prevent unauthorized manipulation of data stored in a page with a write cycle counter associated.