ADC with really "True differential input"

vlad8016 on Nov 18, 2015

Hi collegues.

I need ADC with really differential input and single supply.

-IN connected to reference point (REF/2)

+IN connected to input signal (+\- 2.5v)

I tried AD7684 but DataSheet tells that +IN and -IN MUST be in opposite phase to reference point. I used MCP3301 which is pin2pin compatible with AD7684 but allow any signals on inputs.

Now we need 500kS ADC and MCP3301 couldn`t achieve this.

Could you advice ADC or solution for AD7693 to adapt it to described use case.

Thank you in advance.

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0 jcolao

on Nov 18, 2015 10:23 PM

Hi vlad8016,

What Klaus mentioned are right. There are three most common types of ADC input structure a.) Single- Ended b.) Pseudo Differential c.) True Differential. From your description above I can see that you are looking for ADC that has a pseudo-differential input structure, where the -IN can have a DC input and +IN will have an AC signal. Below is the list of ADIs Pseudo-Differential ADC and is divided base from their sampling rate. You may Consider this list and check them depending on your application. You can go to the ADI website to check the details. Hope this help.

Type	100 kSPS	200 kSPS to 300 kSPS	400 kSPS to 1000 kSPS	1 MSPS to 5 MSPS
16-Bit Pseudo Differential	AD7651	AD7685	AD7652	AD7653
	AD7660		AD7664	AD7667
	AD7661		AD7981
	AD7680		AD7666	AD7980
	AD7683	AD7694	AD7686	AD7983
	AD7988-1		AD7988-5	AD7985

Regards,

Jonathan

Reply

0 jcolao

on Nov 18, 2015 10:23 PM

Hi vlad8016,

Type	100 kSPS	200 kSPS to 300 kSPS	400 kSPS to 1000 kSPS	1 MSPS to 5 MSPS
16-Bit Pseudo Differential	AD7651	AD7685	AD7652	AD7653
	AD7660		AD7664	AD7667
	AD7661		AD7981
	AD7680		AD7666	AD7980
	AD7683	AD7694	AD7686	AD7983
	AD7988-1		AD7988-5	AD7985

Regards,

Jonathan

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