generation  sinusoid with help AD7538

Question

I design electrodrive micromotor. Micromotor supply 3 sinusoid with
variable-amplitude and frequency (0-53 Hz or 0-106 Hz; 540 point on
period). Configuration chanel(1 faze): DAC AD7538 with AD8675,summarize
AD8675, filter 1 or 2 degree on AD8675, power op amp OPA549E. Amplitude
control DAC AD7538 with AD8675(supply on Ref faze DAC chanel). /LDAC use to
simultaneous generation point sinusoid.
Please verify delay your device (if delay bad, repair):
-chanel(1 faze): DAC AD7538 with AD8675 (1,5mks max DAC current rise+
(1/10MHz)*5=0,5mks AD8675); summarize AD8675
(1/10MHz)*5=0,5mks; filter on
AD8675 (1/10MHz)*5=0,5mks + setup time filter
-chanel change amplitude: DAC AD7538 with AD8675 (1,5mks max DAC current rise+
(1/10MHz)*5=0,5mks AD8675)
What is approximately nonsimultaneous in work chanel?
What is recommended for simultaneous generation point sinusoid and
more qualitative generation sinusoid?
Is there change input Ref resistance on change code DAC?
Is there error DAC AD7538 with AD8675 through line A-G AD7538 not R-2R?
AD7538 work with negative Ref?

isantos · Accepted Answer

Hi Aleksei, 
 I took a review at your application and we would like to ask you if you can consider using AD5453 as it is a newer multiplying DAC. 
 Please see below for my answers to your questions: 
 
 What is maximal settling time DAC AD7538 with AD8675? What is maximal settling time summarize AD8675? What is maximal settling time noninverting amplifier AD8675(nonmetering RC circuitry)? What is approximately dispersion on settling time DAC AD7538? What is approximately dispersion on settling time DAC AD8675?

The settling time for the AD7538 will be around 1.5uS for a full scale range, the total settling time for the combination of the devices will really depend on different factors. May I know the sine wave signal frequency you use? how about the Vref value and the maximum output swing of AD8675? 
 Most importantly, what are the values of the RC filter used? It could be possible that the total settling time will be dominated by the RC filter. 
 
 What is recommended for simultaneous generation point sinusoid and more qualitative generation sinusoid? 
 
 > can you please rephrase your question? I am not sure what you mean here. 
 
 Is there change input Ref resistance on change code DAC? 
 
 > The input reference impedance is constant regardless of the DAC code, but the output impedance varies with DAC code. 
 
 Is there glitch (several mV) on change code DAC? 
 
 > 
 Please check table 2, Page 4 of the datasheet 
 
 AD7538 work with negative Ref? 
 
 > Yes, it can work with negative reference voltage, however, the performance might be affected. 
 Hope this helps! 
 Cheers, 
 Ivan)

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generation sinusoid with help AD7538