Device Differences

The overall structure of the ATECC608B is identical to that of the ATECC608A. The ATECC608B does not introduce any new configuration bits and has the same number of data slots as that of the ATECC608A. All commands and command modes are still supported. The device supports both the I2C and SWI interface I/O protocols. The pinouts for the 8-pin SOIC and UDFN packages remain unchanged.

The following sections describe the differences between the ATECC608A and the ATECC608B devices.

Low-Frequency I²C Issue

The ATECC608A has an error in the I2C circuitry, where the device may respond incorrectly under the following conditions:
  • Multiple I2C devices are on the same bus as the ATECC608A.
  • The ATECC608A device was in Idle mode.
  • The I2C operation frequency is ≤ 300 kHz.
  • A data pattern from other devices on the I2C bus could be interpreted by the ATECC608A as a wake pulse.

Under the above conditions, the ATECC608A wakes up and may corrupt data being sent to other devices on the bus. Whether or not data are corrupted depends on the frequency of operation and the actual data being sent.

This issue has been corrected for the ATECC608B device by modifying the I2C circuitry to eliminate this issue. Note that the ATECC608B may still wake up at low frequency but it does not respond or cause data corruption.

Device Revision (DevRev) Differences

The package marking on Microchip security devices does not identify the device type. Therefore, the package marking cannot be used to identify the ATECC608B. The only way to identify the device is through use of the device revision. The hardware device revision of the device can be read by using the Revision mode (0x00) of the Info command. The output response of the Info command for each device is as follows:
Table 1. Revision Response
Device Revision Response
ATECC608A 0x00 0x00 0x60 0x02
ATECC608B 0x00 0x00 0x60 0x03 (Note)
Note: The value of the fourth byte may change over time but it is 0x03 at the time of the initial product release.
Important: The value of the Revision mode response is not the same as the 4-byte RevNum (Bytes[4:7]) in the device configuration zone. Only the Revision mode response can be used for device identification.

Execution Time Differences

The implementation of security enhancements has resulted in changes to the execution times of a few commands. The variation depends on the actual Clock Divider mode as well as the specific mode of operation. The following table shows a list of commands and expected differences in execution times.
Note: For a more detailed understanding of the execution times, refer to the complete data sheet.
Table 2. ATECC608A vs. ATECC608B Execution Time Differences
Command Description of Changes
Verify
  • The execution times of the Verify command will increase by no more than 10%. Actual variation may depend on the specific mode of the command.
  • The execution time increase will occur for all three Clock Divider modes.
SecureBoot
  • The SecureBoot command includes a verify operation. The increase in execution time is due to the Verify portion of this command.
  • The execution times of the SecureBoot command will increase by no more than 10%. Actual variation may depend on the specific mode of the command.
  • The execution time increase will occur for all three Clock Divider modes.
Read
  • The increase in read times is dependent on what is being read.
  • Reads of the configuration zone have increased by roughly 50% (0.8 ms to 1.2 ms) for a 32-byte read.
  • Reads of the data zone have approximately doubled. (0.9 ms to 1.8 ms) for a 32-byte read.
  • This does not apply to reading back a command response. This time will remain the same.
  • The execution time increase does not vary with the Clock Divider modes.
Lock
  • The maximum lock time for either the configuration zone or the data zone increases by approximately 30%.
  • Since production units are shipped in a locked state, this does not impact normal device operation and is just observed by the user during the prototyping or development phase.
  • The execution time increase does not vary with the Clock Divider modes.

Enhanced Temperature Range

The ATECC608A is specified over the industrial temperature range of -40℃ to +85℃.

The ATECC608B is specified over the standard industrial range of -40℃ to +85℃ and an extended range of -40℃ to +100℃, for those users that need an upper ambient temperature value > +85℃. The enhanced temperature range devices have a unique ordering code that is found in the device’s data sheet.

New Packages

The ATECC608B is now available in a 3-pin RBH contact package. This is in addition to the already existing 8-pin SOIC and UDFN packages. This package has been used previously for the ATSHA204A and the ATECC508A CryptoAuthentication devices. The RBH package is only available for devices in SWI interface mode.

The RBH package is a contact package that is typically mounted by gluing the package to an enclosure with the signal pads exposed. Contacts to the pads are usually made through pogo pins when the disposable unit is connected to the host system.