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TMS320F280049: XTALCR SWH question

Part Number: TMS320F280049

Concerning the XTALCR SHW bit:

The TRM describes the XTALCR register SWH bit as 0: for 2 to 10MHz operation, 1: for 10 to 25MHz operation.

Since the F280049 device can operate with single ended XTAL up to 100MHz, it is assumed that one of the following is true:

A) XTALCR.SWH applies only when XTALCR.SW is 0 (in crystal mode) and SWH=1 should be 10-20MHz?

B) XTALCR.SWH = 1 should be for 10MHz to 100MHz.

For now, if using singled ended >25MHz, will just set SWH =1 (either it is a don't care or range should be 10-100MHz).  The 25MHz doesn't match the max 20MHz external crystal or the max 20MHz for single ended with PLL enabled.  So this is a documentation clarification request. 

  • Hi Eric,

    SWH only applies for crystals and not single-ended clocks. The minimum crystal frequency we support is 10MHz (this is documented in the data manual). SWH of 0 is not supported and looks like it made it there by accident. I'll file a bug to get SWH removed from the documentation and registers.