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max io buffer speed in tms320f2810

Arun Gopalakrishnan
Prodigy 150 points

Other Parts Discussed in Thread: TMS320F2810

i'm using the tms320f2810 chip(clock frequency : 150MHz). in the datasheet it is given that maximum IO(GPIO) buffer speed is limited to 20MHz.

1. why it is limited to 20MHz?

2. What will happen if i toggle the GPIO pin more that 20MHz?

3. What is is maximum rate at which i can toggle IO pin safely?

 

Reference :

 Data Manual

Literature Number: SPRS174J

April 2001 - Revised December 2003

page : 108

 

thanks

Arun Gopalakrishnan

  • 0
    TI__Expert 8500 points

    Arun,

    The GPIO buffers are limited to 20MHz for signal integrity reasons. This is a somewhat subjective spec, but it is what TI feels is the maximum speed at which a signal that will always give a nice clear waveform. I think we use a rule of thumb of 10%/90% rise/fall times of <10% of the period. This gives a nice clean squareish waveform. The buffer will actually toggle faster than that if software tells it to. The faster you go the worse the waveform will look, eventually not even hitting the Vol/Voh of the buffers. The frequency that this happens is not specified, but I suppose you could calculate it from the rise/fall times, at least roughly.

    Regards,
    Dave Foley