TMS320C6748: Current into RMII_MHZ_50_CLK pin

Bernhard Boehmer

Part Number: TMS320C6748

Hello TI,

Are there internal diode protection clamps on the RMII_MHZ_50_CLK pin of the TMS320C6748, and if so, what is the maximum I_k clamp diode current, please?

We expect to see a clamp diode to DVDD3318 but initial measurements seem to indicate no diode clamps on this pin - is this correct?

If there are no clamp diodes, what is the max pin voltage allowable with the relevant DVDD3318 = 1.8V?

over 2 years ago

0 Colin Callaghan over 2 years ago

TI__Expert 8155 points

Hi,

I am looking into this but so far have not found the information. There is a reasonable possibility that this information does not exist.

Regards,

Colin

0 Bernhard Boehmer over 2 years ago in reply to Colin Callaghan

Expert 1050 points

Hello Colin,

Thanks, we appreciate your looking into this. Perhaps the design team can shed some light on whether clamp diodes to DVDD3318 were implemented on this pin or not?

0 Bernhard Boehmer over 2 years ago

Expert 1050 points

Hello TI,

If there are no clamp diodes on the RMII_MHZ_50_CLK pin, what is the max pin voltage allowable with the relevant DVDD3318 = 1.8V? Would a 3.0V clock on this input be allowable?

0 Colin Callaghan over 2 years ago in reply to Bernhard Boehmer

TI__Expert 8155 points

Hi Bernhard,

Sourcing a 3.0V signal to the DVDD3318_C group is allowable per the Data Manual. The RMII_MHZ_50_CLK signal falls under group C.

The detail is redundantly clarified in the Power Sequence section:

"There is no specific required voltage ramp rate for any of the supplies as long as the LVCMOS supplies
operated at 3.3V (DVDD3318_A, DVDD3318_B, or DVDD3318_C) never exceed the STATIC 1.8V
supplies by more than 2 volts." In other words, do not exceed 3.8V on the DVDD3318_C supply.

Regards,

Colin

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TMS320C6748: Current into RMII_MHZ_50_CLK pin