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How to choose available ADC/DAC pair, so they can be directly connected?

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harvie

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Hello,
i am looking for "complementary pair" of ADC and DAC. How can i be sure that they will work together before buying and testing their cooperation?

For example i am looking at AD5611 --> AD7477

I want to put analog signal into ADC and then have (almost) identical analog signal at the output of DAC. But datasheets do not say a word about reccomended pair or compatibility between ADCs and DACs.

All i can get is info about available interface (SPI, I2C,...)
I suppose that not all SPI chips are compatible as they can send data in different formats (or data types). Same goes for I2C and other interfaces.

So what is right way to be sure ADC and DAC will play together well? I suppose that bit resolution of both has to match. and DAC should handle at least same speed as ADC (or more). Will these chips cooperate between brands? Is there some general rule to look at ADC/DAC pair and tell if they will cooperate without intermediate mcu or not?


I want to make "analog" isolator using digital isolator between ADC and DAC. And i've read that SPI is better choice than I2C. Is that true? I hope that single simple optocoupler will do the trick with SPI... Also i hope that it will be possible to upgrade to more expensive ADC/DAC pair (with higher resolution) without modyfiing isolation circuit if concept will prove working.
 

AMS012

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Why not use an amplifier or buffer instead of ADC-DAC pair?
 

harvie

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as i said... i want to use digital isolator on the bus between adc and dac...
 

FvM

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ADC/DAC pairs with serial interface, e.g. SPI, can't be never directly connected. They are both slave devices and need to be controlled by a master like a microcontroller or dedicated logic.
 

harvie

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So what solution can you reccomend to me? maybe i dont need SPI ADC/DAC. It can be some high frequency PWM (or other) modulator and demodulator which can make signal go through optocoupler safely without feedback...
 

andre_teprom

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There is an option to do that, but not so much elegant. You can use 2 uC´s at each side, one sending end other receiving. The low cost familly CY8C24 allow synthesize a limited number of analog and digital systems inside, and contais a lot of template modules such as A/D, D/A, UART, SPI, etc...

It is important to know how much speed is required for this application.
I mean, this conversion is part of a loopback control circuit ?
 

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