SPRZ423K October   2014  – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076

 

  1.   1
  2.   Abstract
  3. 1Usage Notes and Advisories Matrices
    1. 1.1 Usage Notes Matrix
    2. 1.2 Advisories Matrix
  4. 2Nomenclature, Package Symbolization, and Revision Identification
    1. 2.1 Device and Development Support Tool Nomenclature
    2. 2.2 Devices Supported
    3. 2.3 Package Symbolization and Revision Identification
  5. 3Silicon Revision C Usage Notes and Advisories
    1. 3.1 Silicon Revision C Usage Notes
      1. 3.1.1 PIE: Spurious Nested Interrupt After Back-to-Back PIEACK Write and Manual CPU Interrupt Mask Clear
      2. 3.1.2 Caution While Using Nested Interrupts
      3. 3.1.3 SYS/BIOS: Version Implemented in Device ROM is not Maintained
      4. 3.1.4 SDFM: Use Caution While Using SDFM Under Noisy Conditions
      5. 3.1.5 McBSP: XRDY Bit can Hold the Not-Ready Status (0) if New Data is Written to the DX1 Register Without Verifying if the XRDY Bit is in its Ready State (1)
    2. 3.2 Silicon Revision C Advisories
      1.      Advisory
      2.      Advisory
      3.      Advisory
      4.      Advisory
      5.      Advisory
      6.      Advisory
      7.      Advisory
      8.      Advisory
      9.      Advisory
      10.      Advisory
      11.      Advisory
      12.      Advisory
      13.      Advisory
      14.      Advisory
      15.      Advisory
      16.      Advisory
      17.      Advisory
      18.      Advisory
      19.      Advisory
      20.      Advisory
      21.      Advisory
      22.      Advisory
      23.      Advisory
      24.      Advisory
      25.      Advisory
      26.      Advisory
      27.      Advisory
      28.      Advisory
      29.      Advisory
      30.      Advisory
      31.      Advisory
      32.      Advisory
      33.      Advisory
      34.      Advisory
      35.      Advisory
      36.      Advisory
  6. 4Silicon Revision B Usage Notes and Advisories
    1. 4.1 Silicon Revision B Usage Notes
    2. 4.2 Silicon Revision B Advisories
      1.      Advisory
      2.      Advisory
      3.      Advisory
      4.      Advisory
      5.      Advisory
      6.      Advisory
      7.      Advisory
      8.      Advisory
      9.      Advisory
  7. 5Documentation Support
  8. 6Trademarks
  9. 7Revision History

Advisory

PLL: Power Down and Bypass May Take up to 120 SYSCLK Cycles to be Effective

Revisions Affected

B, C

Details

When the PLL is powered down (that is, SYPLLCTL1.PLLEN = 0) or bypassed (that is, SYSPLLCTL1.PLLCLKEN = 0), there is a necessary period of clock synchronization before the PLL bypass completes. During this time, if PLLSYSCLKDIV (or other clock divider) is set to a smaller value, the resulting system clock could be unexpectedly more than the rated device frequency.

Implementing the workaround below will allow the PLL bypass operation to complete before any other code is executed, ensuring expected device frequencies and proper system operation.

Workarounds

Add a software delay of 120 SYSCLK cycles using a NOP instruction while performing either a PLL power down or a PLL bypass operation.

Example:


SYSPLLCTL1.PLLCLKEN = 0;       // Bypassing the PLL
asm("  RPT #120 || NOP");      // Delay of 120 SYSCLK Cycles
SYSPLLCTL1.PLLEN = 0;          // Powering down the PLL
asm("  RPT #120 || NOP");      // Delay of 120 SYSCLK Cycles

The latest released C2000Ware, which has this workaround implemented, can be used as reference.