TMS320F280049C: Internal 1.2-V Switching Regulator does not work

Part Number: TMS320F280049C

Dear Sir,

I follow up the datasheet to enable internal 1.2-V switching regulator but I cannot any switching frequency on the pin of VSW (GPIO23).

Could you please tell me what problem on my application? Thank you.

Please refer the configuration as below.

Software: setting the DCDCEN bit in the DCDCCTL register

Hardware:

                Lvsw - 2.2uH

                CVDDIO_SW - 20uF

                CVDD_DECAP - 0.1uF

                CVDD - 20uF

                Tie the VREGENZ pin low to VSS

Best Regards,

Johnson