ADS8319: Data converters forum

Y.Ottey

Part Number: ADS8319

Dear all,

I would like to ask following questions about datasheet.

1.According to Fearture on page 1 of the data sheet, the input voltage range is indicated as Single-Ended Input Range: 0 V to VREF.

Is it safe to assume that this input voltage range has the same meaning as the Pseudo differential analog input range?

2.According to Recommended Operating Conditions on page 4 of the data sheet, the reference voltage is written as follows.

I would like to use the reference voltage at 4.5V. Is there any problem?

I need to know the answers above quickly

I would appreciate it if you could get back to me right away.

Best Regards,

Y.Ottey

over 6 years ago

0 Keith Nicholas over 6 years ago

TI__Guru 50310 points

Hello Y.Ottey,

Question 1:

The ADS8319 is considered a single ended input. The negative input, pin 4 (-IN) is typically connected to GND, but does allow for a slight variation from GND by +/-100mV to account for ground offsets in the system.

For a pseudo differential input, the negative input (-IN) would connect to 1/2 of the VREF. If using a 4.5V reference, you would connect -IN to 2.25V. However, the ADS8319 does not support this input voltage level on the negative input, so it is considered a single ended input.

Please take a look at TI Precision Labs - ADC's for a more detailed description; specifically section 2.1.

https://training.ti.com/ti-precision-labs-adcs-sar-adc-input-types?cu=1128375

Question 2:

Yes, you can use VREF=4.5V. VREF can be as high as VA+0.1V. Just make sure that VA supply voltage is never less than the minimum 4.5V and you will not have any problem.

Regards,
Keith Nicholas
Precision ADC Applications

0 Y.Ottey over 6 years ago in reply to Keith Nicholas

Mastermind 6145 points

Hi Keith,

Thank you for your reply.

I understand about pseudo differential input.

I would like to ask more question.

Now, I am considering the ADS8319 as an alternative to the following products.

https://www.analog.com/media/en/technical-documentation/data-sheets/AD7685.pdf

At that time, Psuedo differential input range is defined in the following products, but the input range is defined as shown in the table below.

The ADS8319 also shows the input voltage range in the same notation. Is it safe to recognize it as the same input voltage range?

Regards,

Y.Ottey

0 Keith Nicholas over 6 years ago in reply to Y.Ottey

TI__Guru 50310 points

Hello Y.Ottey,

Now I understand the source of confusion. It appears there is not a consistent definition of pseudo-differential.

Yes, Both devices have the same input range requirements.

-IN from -100mV to +100mV.

+IN from -100mV to VREF+100mV (+IN can continue up to +VA+100mV safely, but output will read full scale for +IN-(-IN)>VREF).

Regards,
Keith