Author Topic: 24 bit ADC converter with PGA working from 0V?  (Read 2750 times)

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Offline A2

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24 bit ADC converter with PGA working from 0V?
« on: July 15, 2014, 04:15:34 pm »
I had used ADS1248, it had PGA which can wirk with AVSS+0.1V. So I cannot measure sinle ended signal reference to ground.

I found another IC, ADS1220, it works if we bypass PGA. But it has 4 channel unlike ADS1248 which has 8 channles?

Any one IC with 8 channels & can do sinle ended measurement of small signals of range 50mV
 

Offline adi101

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Re: 24 bit ADC converter with PGA working from 0V?
« Reply #1 on: July 15, 2014, 08:42:55 pm »
Look at this:
http://www.microchip.com/wwwproducts/Devices.aspx?product=MCP3914

It works with signals between +1V and -1V at the inputs.
Very good performance at high OSR.
Plus you get 8 independent synchronous ADCs.
 

Offline NANDBlog

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Re: 24 bit ADC converter with PGA working from 0V?
« Reply #2 on: July 15, 2014, 08:54:07 pm »
ADS1256
Those fancy AFEs are nice for what they were designed for, but not much else. This includes all 3 devices mentioned here, the TI parts are for temperature sensors, the microchip is for energy metering. Dont use them to measure industrial signals, something obvious will not work. This can include INL, DNL errors, stupid digital interface, settling time issues etc.
 

Offline adi101

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Re: 24 bit ADC converter with PGA working from 0V?
« Reply #3 on: July 15, 2014, 09:15:16 pm »
the microchip is for energy metering

Don't be intimidated by that, in fact energy metering requires very high accuracy.
Anyway, an ADC is an ADC, you can use it in many different applications.
Differential inputs are very good at rejecting noise too (just food for thought).
 

Offline NANDBlog

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Re: 24 bit ADC converter with PGA working from 0V?
« Reply #4 on: July 15, 2014, 09:45:21 pm »
the microchip is for energy metering

Don't be intimidated by that, in fact energy metering requires very high accuracy.
Anyway, an ADC is an ADC, you can use it in many different applications.
Differential inputs are very good at rejecting noise too (just food for thought).
The problem is, that he was asking for a srewdriver, and you gave him a hammer. A2 obviously wants to measure 0-5V signals, whicha are single ended. If he choses the AFE you proposed, the signal must be divided first to the input range, sacrificing all the accuracy.
The MCP3914 doesnt have any DC accuracy. It has 0,1% offset and 9PPM reference, together with 4% gain error compared to the ±0.005% error from the device I proposed. You need to feed a clock into it, and the power supply is different.
I mean, sure, you can say that you can sample it with a wolfson audio adc, and then convert the I2S signal to SPI, because that is also an ADC, right?
 

Offline adi101

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Re: 24 bit ADC converter with PGA working from 0V?
« Reply #5 on: July 16, 2014, 06:56:02 am »
There is no need to argue which ADC is better.
Each has advantages and disadvantages.
I was just pointing a device which I know is very good.

I am sure that the ADS part is also very good.
Let him choose according to his application.
« Last Edit: July 16, 2014, 06:59:29 am by adi101 »
 


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