AD7606C-16 || Digital Data to Voltage Conversion

Hello arijeet06 ,

I will contact the product owner and get back to you.

Regards,
Jo

Hi Nathan,

Awaiting your early response.

Hi Rehfi, Nathan,

We have observed that the ADC is set in Low Bandwidth Mode. To verify this we have carried out the gain-freq. response. 

Below are our observations;





Datasheet Graph:



Our operating freq. is 27Khz, and the gain is nearly -3dB to this point.

Hello arijeet06 ,

Sorry for the late response. But upon reading your query, your main concern is "What Should I consider the Full Scale Range for my calculation?"

And to answer that, it would be depending on the voltage range selected. By default, it would be 10V.

Meanwhile, what is your question based on your last post in this thread? You have mentioned of using Low Bandwidth mode.

Thanks and regards,
Jo

Hi Nathan,

To my last query;

" When measuring my ADC input at V1+ wrt GND I am observing ~1.4Vpp, similarly, at V1- wrt GND I am observing ~1.4Vpp. So, Input to ADC will be ~2.8Vpp.

But, while capturing from ADC (Digital Data, as you said) ~1.56Vpp is calculated.

I used the same formula of multiplying the digital data with 305.2 µV & took the min/max (assumed not hitting the max), I m observing ~1.74Vpp (less than 2.8Vpp) " 

to this, we observed the ADC is configured in the low bandwidth mode. For this, we shared our observation (freq. vs gain) plot in the last thread.

Ooooh... Good catch, arijeet06 . I totally forgot about the filter.

Regards,

rehfi

Hi arijeet,

this tool allows you to see the filter response vs frequency (among many other features) https://www.analog.com/media/en/engineering-tools/design-tools/ad7606x-software-model-2-1.zip

At 28kHz you should expect around 3.5dB attenuation, what seems to match approximately what you are seeing?

Regards,

Lluis.

Hi Nathan, Lluis, Rehfi..

We tried writing the registers with the below-required value.

1. 0x03 - 88 (+/-5V differential range)
2. 0x04 - 88 (+/-5V differential range)

3. 0x05 - 88 (+/-5V differential range)

4. 0x06 - 88 (+/-5V differential range)

5. 0x07 - FF (setting high bandwidth)

6. 0x00 - 00 (referred from previous posts to set back to AC mode).

we are using a 96-clock cycle in total for writing the above data, but we observed the ADC is not coming out of register mode. & I am able to see the register data on DOUTA line(by probing)

Any suggestion on this.  


 

Hi Nathan, Lluis, Rehfi..

We tried writing the registers with the below-required value.

1. 0x03 - 88 (+/-5V differential range)
2. 0x04 - 88 (+/-5V differential range)

3. 0x05 - 88 (+/-5V differential range)

4. 0x06 - 88 (+/-5V differential range)

5. 0x07 - FF (setting high bandwidth)

6. 0x00 - 00 (referred from previous posts to set back to AC mode).

we are using a 96-clock cycle in total for writing the above data, but we observed the ADC is not coming out of register mode. & I am able to see the register data on DOUTA line(by probing)

Any suggestion on this.  


 

Hi arijeet

So, after step 6, what are you doing next? do you perform more read operations and what do you get back on DOUTA? Can you send scope shots of this 6 steps plus several more read frames?

Are you issuing CNVST pulses in between in order to trigger new conversion?

Regards,

Lluuis.

Hi Lluis,

After step 6, I not doing any more writing operations, so my SDI line is low. 

For ADC mode I am using only DOUTA, DOUTB, after doing the above registers write operation, DOUTB line is low, only toggles are observed on DOUTA (data seems similar to what I wrote to the registers). 

My convst pulse is at 108k, 

I will send you the snapshots by EOD.

I am planning to probe SCLK & DOUTA. Anymore probe shots you are looking for

Hi Lluis,

Attached the scope shots. 

https://docs.google.com/document/d/1LWLevyR2UD0U_PrIe37mn5vmLGg51r-cBEXdJWmKoiM/edit?usp=sharing

let me know if you can open this

Hi Lluis,

I hope you can open the sheet, 

Kindly suggest if we are missing anything.

Team, Awaiting for response

Hi NathanT Lluis 

Awaiting our response.

One more thing I observed, If I am trying to read the device ID I am getting 0x12. 
Attached the GUI snap.


Do you find any discrepancy in the capture?

Hi Arijeet06,

I am afraid I don't have access to that google docs file. Can you send it by another means?

The device ID should actually be 0x22.

(+) What's the ID register content for each generic? - Documents - Precision ADCs - EngineerZone (analog.com)

Regards,

Lluis.

Hi Lluis 
I have shared the Vivado GUI snap, do you find any discrepancy in the capture?

Also I tried to read the 0x03 register but instead of 0x33 i was reading 0x32.

Reg. google docs, which means do you suggest to share the data?

Hi arijeet,

Then something is wrong on the SPI interface. You are missing the LSB. Wondering if the CPHA and CPOL is properly configures in the host?

Regards,

Lluis.

Hi Lluis 
I see the same waveform in the oscilloscope too.

Which mode I should configure ADC-SPI for read & write operations?