Your DAC that have a AGND-bias function like a AD7226

Hi Kaos-san,

Apologies for the delayed response.

They do not work similar to the bias function. Although the absolute maximum ratings table says that the VREF pins can go as low as Vss -0.3 V up to Vdd + 0.3 V. Note that if a voltage within this range but outside the specs table range is used, ADI guarantees that the part will tolerate the voltages/currents but the behavior is unexpected and the part does not operate at those conditions. On the other hand, the specifications table states that a range of -5V to 0V can be applied to the –Vref pin. If we stick to a voltage within this range, ADI guarantees that the part will behave as expected and all specifications will be met.

In other words, the AD7835 and AD7836 can use the Vref- as Bias function but performance cannot be guaranteed as specified in the data sheet.

Unfortunately the newer DACs do not implement this circuitry. What we can do is suggest an external circuitry that would work similarly to the AGND bias functionality. We could use a non-inverting summing amplifier. Using the configuration, the bias voltage and the output of the DAC will add up and get an adjusted output range that is from the bias voltage up to bias voltage + DAC output voltage. At this point of the circuitry, the customer can use any other newer DAC of their choice.

Hope this helps.

Regards,

Mark

Hi Kaos-san,

Apologies for the delayed response.

They do not work similar to the bias function. Although the absolute maximum ratings table says that the VREF pins can go as low as Vss -0.3 V up to Vdd + 0.3 V. Note that if a voltage within this range but outside the specs table range is used, ADI guarantees that the part will tolerate the voltages/currents but the behavior is unexpected and the part does not operate at those conditions. On the other hand, the specifications table states that a range of -5V to 0V can be applied to the –Vref pin. If we stick to a voltage within this range, ADI guarantees that the part will behave as expected and all specifications will be met.

In other words, the AD7835 and AD7836 can use the Vref- as Bias function but performance cannot be guaranteed as specified in the data sheet.

Unfortunately the newer DACs do not implement this circuitry. What we can do is suggest an external circuitry that would work similarly to the AGND bias functionality. We could use a non-inverting summing amplifier. Using the configuration, the bias voltage and the output of the DAC will add up and get an adjusted output range that is from the bias voltage up to bias voltage + DAC output voltage. At this point of the circuitry, the customer can use any other newer DAC of their choice.

Hope this helps.

Regards,

Mark