SPRABF9 March   2019 TMS320C6742 , TMS320C6742 , TMS320C6746 , TMS320C6746 , TMS320C6748 , TMS320C6748

 

  1.   1
  2.   Trademarks
  3. 1Introduction
  4. 2Model Activity
    1. 2.1 Activity-Based Models
    2. 2.2 Baseline Power
    3. 2.3 Activity Power
    4. 2.4 Modules
  5. 3Using the Power Estimation Spreadsheet
    1. 3.1 Choosing Appropriate Values
      1. 3.1.1 Utilization
      2. 3.1.2 % Writes
      3. 3.1.3 % Switching
  6. 4Using the Results
    1. 4.1 Adjusting I/O Power Result
  7. 5Thermal Considerations
  8. 6Example
  9. 7Limitations
  10. 8References

3.1.3 % Switching

As mentioned previously, the C6748/46/42 device provides the capability to disable modules that are not being used via the power sleep controller (PSC). When a peripheral is disabled, its clock is turned off reducing the power consumption of the device.

The spreadsheet accommodates this power saving feature by including fields from which a peripheral can be specified as disable or enabled.

If a module is not used for a given application, then it is recommended to keep it in a disabled state.

It is possible that the module is kept enabled but has no activity. To achieved this, program the % utilization and/or the frequency fields to a value of 0, then the numbers in the module's row will be indicative of the power consumed by clocking the module.

It is also possible for some modules to be disabled but still have activity. For example, EMAC will continue to generate a 50 Mhz RMII clock for the PHY even when disabled. To eliminate the RMII clock activity, set the EMAC "Other" parameter to "RMII clk input". Another example is the USB PHYs. Both USB1.1 and USB2.0 PHY can be powered and enabled without having the USB modules enabled. To remove the PHY power consumption, set the USB "Other" parameter to "No Activity".