19-5236 Rev 2/12 DS2430A 256-Bit 1-Wire EEPROM FEATURES PIN ASSIGNMENT 256-bit Electrically Erasable Programmable TO-92 TSOC PACKAGE Read Only Memory (EEPROM) plus 64-bit DALLAS 1 6 DS2430A one-time programmable application register 2 5 Unique, factory-lasered and tested 64-bit 3 4 registration number (8-bit family code + 48-bit TOP VIEW serial number + 8-bit CRC tester) assures 3.7mm x 4.0mm x 1.5mm absolute identity because no two parts are alike Built-in multidrop controller ensures compatibility with other MicroLAN products SIDE VIEW EEPROM organized as one page of 32 bytes for random access Reduces control, address, data, and power to a single data pin 1 2 3 Directly connects to a single port pin of a microprocessor and communicates at up to 15.3kbits per second 8-bit family code specifies DS2430A 1 2 3 communication requirements to reader Presence detector acknowledges when reader first applies voltage BOTTOM VIEW Low cost TO-92 or 6-pin TSOC and UCSP surface mount package NOTE: The leads of TO-92 packages on tape and reel are formed to approximately 100-mil (2.54mm) spacing. For details see the Reads and writes over a wide voltage range of Package Information. 2.8V to 5.25V from -40C to +85C PIN DESCRIPTION ORDERING INFORMATION TO-92 TSOC PART TEMP RANGE PIN-PACKAGE Pin 1 Ground Ground DS2430A+ -40C to +85C 3 TO-92 Pin 2 Data Data DS2430A+T&R -40C to +85C 3 TO-92 (2k pcs) Pin 3 NC NC DS2430AP+ -40C to +85C 6 TSOC Pin 4 NC DS2430AP+T&R -40C to +85C 6 TSOC (4k pcs) +Denotes a lead(Pb)-free/RoHS-compliant package. Pin 5 NC T&R = Tape and reel. Pin 6 NC 1 of 19 NOT RECOMMENDED FOR NEW DESIGNSDS2430A DESCRIPTION The DS2430A 256-bit 1-Wire EEPROM identifies and stores relevant information about the product to which it is associated. This lot or product specific information can be accessed with minimal interface, for example a single port pin of a microcontroller. The DS2430A consists of a factory-lasered registration number that includes a unique 48-bit serial number, an 8-bit CRC, and an 8-bit Family Code (14h) plus 256 bits of user-programmable EEPROM and a 64-bit one-time programmable application register. The power to read and write the DS2430A is derived entirely from the 1-Wire communication line. Data is transferred serially via the 1-Wire protocol, which requires only a single data lead and a ground return. The 48-bit serial number that is factory-lasered into each DS2430A provides a guaranteed unique identity that allows for absolute traceability. The TO-92 and TSOC packages provide a compact enclosure that allows standard assembly equipment to handle the device easily for attachment to printed circuit boards or wiring. Typical applications include storage of calibration constants, board identification, and product revision status. OVERVIEW The block diagram in Figure 1 shows the relationships between the major control and memory sections of the DS2430A. The DS2430A has four main data components: 1) 64-bit lasered ROM, 2) 256-bit EEPROM data memory with scratchpad, 3) 64-bit one-time programmable application register with scratchpad and 4) 8-bit status memory. The hierarchical structure of the 1-Wire protocol is shown in Figure 2. The bus master must first provide one of the four ROM Function Commands: 1) Read ROM, 2) Match ROM, 3) Search ROM, 4) Skip ROM. The protocol required for these ROM Function Commands is described in Figure 8. After a ROM Function Command is successfully executed, the memory functions become accessible and the master can provide any one of the four memory function commands. The protocol for these memory function commands is described in Figure 6. All data is read and written least significant bit first. 64-BIT LASERED ROM Each DS2430A contains a unique ROM code that is 64 bits long. The first 8 bits are a 1-Wire family code (14h). The next 48 bits are a unique serial number. The last 8 bits are a CRC of the first 56 bits. (Figure 3). The 1-Wire CRC is generated using a polynomial generator consisting of a shift register and XOR 8 5 4 gates as shown in Figure 4. The polynomial is X + X + X + 1. Additional information about the 1-Wire CRC is available in Application Note 27. The shift register bits are initialized to 0. Then starting th with the least significant bit of the family code, one bit at a time is shifted in. After the 8 bit of the th family code has been entered, then the serial number is entered. After the 48 bit of the serial number has been entered, the shift register contains the CRC value. Shifting in the 8 bits of CRC should return the shift register to all 0s. 1-Wire is a registered trademark of Maxim Integrated Products, Inc. 2 of 19 NOT RECOMMENDED FOR NEW DESIGNS