[SOLVED] ADC application circuit

[aminpix]

I have a design with max19507. It seems the default analog input (ADC input) is between 0.4 and 1.4V. (I have connected IN- to ground and IN+ to the input signal.)

Is there anyway to change the input analog range to 0 - 2.5v? In page 15 of the datasheet it has been described but I am not sure I understand it or not. If I connect REFIO pin to 2.5v the voltage range will change to 0 - 2.5v?

Am I right?

Here is the link of the datasheet

https://datasheets.maximintegrated.com/en/ds/MAX19507.pdf

 

[KlausST]

Hi,

i think you misunderstood the datasheet.
Reference voltage is 1.25V. External or internal, in either case. The range is very limited to +5/-15 percent. 2.5V is definitely not alloed.

There is a common mode input voltage range of 0.4...1.4V. So connecting one input to 0V is not allowed.
There is a differential input voltage range of 1.5Vpp. It means +/- 0.75Vp

The input aplication schematics are AC coupled. You can´t measure DC with them.
If you need DC, then i recommend to use an input buffer similar to LTC6263.

Klaus

 

[aminpix]

For DC coupling I plan to use this circuit.

Does it works?

And about the voltage range, what is "+5/-15 percent"? does it mean I can have 1.25 Vpp ?

 

[KlausST]

Hi,

did you read this?

There is a common mode input voltage range of 0.4...1.4V. So connecting one input to 0V is not allowed.
There is a differential input voltage range of 1.5Vpp. It means +/- 0.75Vp

The input aplication schematics are AC coupled. You can´t measure DC with them.
If you need DC, then i recommend to use an input buffer similar to LTC6263.

Klaus

 

[aminpix]

How to use LTC6263 ?

 

[KlausST]

Hi,

Sorry, it is LTC6362. Read datasheet. It is explained very wel.

If after reading still something is unclear, ask again.

Klaus