Abstract: The DS2703 SHA-1 battery pack authentication IC provides a reliable encryption scheme to ensure the legality of lithium-ion battery packs in various portable applications. The DS2703 can accept 11 kinds of functional commands, and each command has a specific timing. To execute the command correctly, the timing must be followed. This application note provides the complete transmission timing and all possible communication timing flow charts of the DS2703.
Introduction The DS2703 SHA-1 battery pack authentication IC provides a reliable encryption scheme to ensure the legality of lithium ion (Li +, Li-ion) battery packs in various portable applications. The device uses a secure hash algorithm (SHA-1) to authenticate the legality of battery packs in host systems (eg, cell phones, PDAs, or other portable computing devices). Integrating the DS2703 into the battery pack ensures that the host can identify unauthorized battery packs, thereby avoiding such battery packs from affecting system performance or harming users.
The DS2703 can accept 11 kinds of functional commands, and each command has a specific timing. To execute the command correctly, the timing must be followed. This application note provides a complete transmission timing description and all possible communication timing flow charts of the DS2703.
Transmission sequence The protocol for accessing the DS2703 through the 1-Wire® port is as follows: Initialize network address command function Command data transmission (not all commands have data transmission) All transmissions on the 1-Wire bus start with an initialization sequence and are initiated by the host The reset pulse and the response pulse that DS2703 and other slave devices on the bus respond to at the same time. The response pulse informs the master that one or more slave devices are on the bus and are ready.
Once the network addressing command detects one or more slave devices on the bus, the host can issue one of the following network addressing commands: Read, Match, Search, or Skip command. Figure 1 shows the transmission flow chart of each network addressing command.
Figure 1. DS2703 network addressing command flow chart
After the function command is initialized and the network addressing command ends, the DS2703 is ready to receive the function command sent by the bus master. Table 1 contains 11 function commands that DS2703 can accept, and a brief description of these commands. Figure 2 shows the flow chart required for the DS2703 to properly execute each command. Function commands that require the host to issue the same sequence are represented by a single branch in the flowchart.
Table 1. All function commands
Figure 2. DS2703 function command flow chart
Conclusion To correctly execute the function commands of DS2703, you must follow a specific timing sequence, which must be implemented by specific timing constraints. This application note provides a complete description of the transmission timing and provides a flow chart for all possible communication timing of the DS2703.
Introduction The DS2703 SHA-1 battery pack authentication IC provides a reliable encryption scheme to ensure the legality of lithium ion (Li +, Li-ion) battery packs in various portable applications. The device uses a secure hash algorithm (SHA-1) to authenticate the legality of battery packs in host systems (eg, cell phones, PDAs, or other portable computing devices). Integrating the DS2703 into the battery pack ensures that the host can identify unauthorized battery packs, thereby avoiding such battery packs from affecting system performance or harming users.
The DS2703 can accept 11 kinds of functional commands, and each command has a specific timing. To execute the command correctly, the timing must be followed. This application note provides a complete transmission timing description and all possible communication timing flow charts of the DS2703.
Transmission sequence The protocol for accessing the DS2703 through the 1-Wire® port is as follows: Initialize network address command function Command data transmission (not all commands have data transmission) All transmissions on the 1-Wire bus start with an initialization sequence and are initiated by the host The reset pulse and the response pulse that DS2703 and other slave devices on the bus respond to at the same time. The response pulse informs the master that one or more slave devices are on the bus and are ready.
Once the network addressing command detects one or more slave devices on the bus, the host can issue one of the following network addressing commands: Read, Match, Search, or Skip command. Figure 1 shows the transmission flow chart of each network addressing command.
Figure 1. DS2703 network addressing command flow chart
After the function command is initialized and the network addressing command ends, the DS2703 is ready to receive the function command sent by the bus master. Table 1 contains 11 function commands that DS2703 can accept, and a brief description of these commands. Figure 2 shows the flow chart required for the DS2703 to properly execute each command. Function commands that require the host to issue the same sequence are represented by a single branch in the flowchart.
Table 1. All function commands
| COMMAND | HEX | FUNCTION |
| Write Challenge | 0C | Writes 64-bit challenge for SHA-1 processing; required prior to all Compute MAC and Compute Next Secret commands |
| Compute MAC Without ROM_ID and Return MAC | 36 | Computes hash of W0–W15 with logical 1's in place of the ROM_ID |
| Compute MAC With ROM_ID and Return MAC | 35 | Computes hash of W0–W15 with the ROM_ID |
| Load Secret | 5A | Writes the 64-bit secret to supplied data; requires programming voltage on DQ |
| Compute Next Secret Without ROM ID | 30 | Generates new global secret; requires programming pulse |
| Compute Next Secret With ROM ID | 33 | Generates new unique secret; requires programming pulse |
| Lock Secret | 6A | Sets lock bit to prevent changes to the secret; requires programming pulse |
| Set Overdrive | 8B | Sets 1-Wire interface TImings to OVERDRIVE; requires programming pulse |
| Clear Overdrive | 8D | Sets 1-Wire interface TImings to STANDARD; requires programming pulse |
| AcTIvate Thermistor | A9 | Activates the THM output for thermistor measurement; activation occurs within 50µs of command completion and continues until the VB capacitor is discharged |
| Reset | BB | Resets the DS2703 (software POR) |
Figure 2. DS2703 function command flow chart
Conclusion To correctly execute the function commands of DS2703, you must follow a specific timing sequence, which must be implemented by specific timing constraints. This application note provides a complete description of the transmission timing and provides a flow chart for all possible communication timing of the DS2703.
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