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F28335 1.8V or 1.9V?

Leong
Expert 1070 points

Other Parts Discussed in Thread: TPS62400

Hi, I'm on a new F28335 based design. Can any one explain a bit on the topic of the secondary power supply as 1.8V vs.1.9V? I have a control card that uses 1.8V and an EZdsp board seems to have 1.9V chip then after the LC it was labeled as VDDA_1V8. 

 

Thanks

  • 0
    Expert 1315 points

    Hi,

    I think it is to do with clock speed. If you run the DSP at 150MHz, then the voltage should be 1.9V. If you run at 100MHz, you can use 1.8V. I suspect that the original intention was to have a 1.8V supply for all clock speeds, but higher voltage for higher speeds turned out to be necessary in practice: hence the EZdsp documentation having the 1.8V labelling.

    Cheers,

    John.

  • 0 in reply to John Wilkes
    Expert 1070 points

    Thanks John,

     

    Indeed, the label is 1V8 on the control card schematic but calculation shows that the actual output from the power supply chip (TPS62400) is 1.9V.

     

    Regards

     

    Leong