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Datasheet Modifications regarding I2C Bus Mode Control

Dear Customer

Please be advised of the modifications to be made to the “I2C Bus Mode Control” section in the technical data sheets of our microcontrollers. The microcontrollers that are affected by this issue are listed on the tabbed pages according to product series. In these microcontrollers it has been found that the I2C circuit allows the setting of baud rates that do not meet the Philips I2C specification.

Affected usage conditions
This issue concerns the case where the I2C bus is used in the Fast mode (over 100 kbps). It also applies if the I2C bus is used at or below 100 kbps but with no consideration for the clock duty of the SCL clock.
Issue
This I2C bus circuit does not support communications in the Fast mode (up to 400 kbps). However, it is nevertheless possible to set a baud rate exceeding the limit set by the Standard mode (up to 100 kbps). Although the exact equations vary with each product, a communication baud rate that does not meet the I2C specification may be set depending on the microcontroller’s clock and baud rate generator settings.
Notes to be added to the technical datasheets
  • This I2C bus circuit does not support the Fast mode. It supports the Standard mode only. Although the I2C bus circuit itself allows the setting of a baud rate over 100 kbps, the compliance with the I2C specification is not guaranteed in that case.
  • Set a communication baud rate that meets the I2C bus specification, such as the shortest pulse width of tLOW, based on the specified equations.
If you are already using the I2C bus in the Fast mode (over 100 kbps)

If you are already using the I2C bus in the Fast mode (over 100 kbps), please contact us. We will consult with each individual customer for the appropriate solution. The following are the I2C specifications not supported by our microcontrollers.

  1. The SCL (clock) and SDA (data) inputs do not support Schmitt trigger inputs.
  2. The SCL (clock) and SDA (data) outputs do not incorporate slope control of falling edges.
  3. The A.C. specification in the Fast mode (over 100 kbps) is not supported.
  4. When the power to the microcontroller is turned off, the I/O pins of SCL and SDA should be disconnected from the power supply to prevent interference in the bus lines of other connected I2C devices. However, this function is not supported.

The above 1 to 3 are the misoperation-preventative requirements to support the Fast mode, and the above 4 is the new function required for the Fast mode.

Product name
TOSHIBA Microcontrollers TLCS-870/C Series

TOSHIBA Microcontrollers TLCS-870 Series

TOSHIBA Microcontrollers TLCS-870/X Series

TOSHIBA Microcontrollers TLCS-900/L Series

TOSHIBA Microcontrollers TLCS-900/L1 Series

TOSHIBA Microcontrollers TLCS-900/H1 Series

Note: Discontinued products may not be included in the affected products list. Please contact your local Toshiba office or authorized Toshiba dealer for details.

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·Before creating and producing designs and using, customers must also refer to and comply with the latest versions of all relevant TOSHIBA information and the instructions for the application that Product will be used with or for.