Electronic – DAC: What waveform should I expect when ramping up

dac

I have a 14-bit DAC. Ramping the data pins linearly from the minimum of 0x0 to the maximum of 0x3FFF I see (using a scope) the analogue output voltage behaving as follows:

  1. In the first half (from 0x0 to 0x2000), the voltage ramps from 1V to 1.8V.
  2. In the second half (from 0x2000 to 0x3FFF), the voltage ramps from 0V to 1V.

Is this the expected behaviour? What output voltage range should I be expecting for the analogue output? Why is there a "break" at 0x2000?

Best Answer

I've figured out part of the answer. The break is due to the two's complement option being turned on (see page 14):

Logic “0” (default) causes data to be accepted on the inputs as two’s complement binary. Logic “1” causes data to be accepted as straight binary.

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