DDR-to- offset binary solution?

Robert Livingston

Other Parts Discussed in Thread: SN75LVDT386

Is there a recommended solution for use of the AD5481,2,3 series of ADC converters with the GC5016 DDC? The ADC has offset-binary LVDS output, while the DDC has two-complement input.

I think it can be done using a LVDS receiver (e.g. SN75LVDT386) with reversed MSB lines, but I suspect that there may be a better approach.

Thanks for any guidance.

over 14 years ago

0 Richard Prentice over 14 years ago

TI__Mastermind 29220 points

hi,

reversing the polarity of one of the LVDS lines won't work because the most significant bit is on the same LVDS pair as the next-most least significant bit, DDR fashion. So if you invert the LVDS pair then you invert the msb, (which is what you want for going from offset binary to 2's complement) but you also will have inverted the msb-1. That would not be good.

if the GC5016 will not have an option for accepting offset binary, then i think you would need some glue logic (like a small programmable device) to take the DDR data apart into sample data to invert the msb and then output again in DDR or whatever format the GC5016 would accept.

Regards,

Richard P.

0 Philip Pratt over 14 years ago

TI__Intellectual 1965 points

You may also want to have a look at the new GC6016, on www.ti.com.

Thanks.

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DDR-to- offset binary solution?