1 Device Differences

The overall structure of the ATECC608C is identical to that of the ATECC608B. The ATECC608C does not introduce any new configuration bits and has the same number of data slots as that of the ATECC608B. 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, 8-Pad UDFN and 3-Lead Contact package all remain unchanged. The V_CC voltage range, temperature ranges and power specifications are all identical to that of the ATECC608B.

The following sections describe the differences between the ATECC608B and the ATECC608C devices.

Low-Temperature Lockup Issue

In a low number of devices, it was observed that, under low temperature conditions, the device would sometimes lock up when initially powering up. This lockup was due to the SCL pin changing state and switching to a GPIO output mode, as it is used in the Single Wire Interface (SWI) mode, and holding the SCL signal low. Typically, powering off the device and restarting the device would correct the issue.

This issue was corrected for the ATECC608C device by modifying the internal start-up circuitry and ensuring that the device will resolve to the correct state upon waking up the device. A new parameter was added to the data sheet called t_{DVC_INIT} that shows at what point the device is guaranteed to be in the correct state. It is recommended that no communication occur prior to this point to the ATECC608C or any other device on the I²C bus. The following diagram illustrates the timing.

Important: Parameters, t_PU, t_WLO, t_WHI and t_WHIST values were not changed from the ATECC608B. The t_{DVC_INIT} time is less than the t_WHI/t_WIHST time, so the overall start-up time did not increase with this modification.

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 ATECC608C. The only way to identify the device is through the use of the device revision. The hardware 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 1-1. Revision Response
Device	Revision Response
ATECC608B	0x00 0x00 0x60 0x03
ATECC608C	0x00 0x00 0x60 0x05^{(1, 2)}

Tip:

The value of the fourth byte may change over time but it is 0x05 at the time of the initial product release.
The value of the Revision mode response may not be the same as the 4-byte RevNum (Bytes[4:7]) in the device configuration zone. Only the Revision mode response of the Info command can be used for device identification.

Execution Time Differences

The implementation of security enhancements resulted in changes to the execution times of a few commands. The variation observed was very minimal and could have slightly improved or gotten worse. The only execution time change identified as a specification change in the data sheet is shown in the table below.

Note: For a more detailed understanding of the execution times, refer to the complete data sheet.

Table 1-2. ATECC608B vs. ATECC608C Execution Time Differences
Command	Description of Changes
`Read`	The maximum execution times of the `Read` command when writing to data slots increased from 2.0 ms to 2.5 ms. The timing of the Read command does not vary with the clock divider modes, so this increase occurs in all clock divider modes.