4kbit 1-Wire RAM with Counter
DescriptionThe 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 read-only. 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.
- 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
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