AD7671 Output has step

Hi,

 When I use AD7671 to convert signal (1Hz to 1kHz), I found steps in the output.

Attachment figure 1 is the waveform, where green line is input of AD7671;yellow line is the output of AD7671 (a DCA output, the DAC operated well).

Parents
  • Hi Henry Zhang,

       You mentioned that you did a voltage divider on the ADR01 to have an output of 2.5V as reference to the AD7671. Where was the resistor connected? The total impedance on the reference output can interact with the ADC required reference voltage. With the impedance and the 200uA reference current of the AD7671 would affect the stability of the reference voltage during conversion. The AD7671 technology is a  switch cap dac. During transition from acquisition phase there is a large current requirement from the reference.

       On one of the snapshot, the time between each level is 62khz which is almost equal to the sampling rate. Would you be able to check the result when lowering the sampling rate.

    Regards,

    Jonathan

Reply
  • Hi Henry Zhang,

       You mentioned that you did a voltage divider on the ADR01 to have an output of 2.5V as reference to the AD7671. Where was the resistor connected? The total impedance on the reference output can interact with the ADC required reference voltage. With the impedance and the 200uA reference current of the AD7671 would affect the stability of the reference voltage during conversion. The AD7671 technology is a  switch cap dac. During transition from acquisition phase there is a large current requirement from the reference.

       On one of the snapshot, the time between each level is 62khz which is almost equal to the sampling rate. Would you be able to check the result when lowering the sampling rate.

    Regards,

    Jonathan

Children
No Data