ADS1252 The Bipolar input +/-5V

[hamdan]

ads1252

Hi All,

I am new to designs. I need to use the ADS1252. The Bipolar input is +/-5V.
Do I need to use +5V, -5V for the OP amp? In that case I cannot use OPA2350 since the maximum rating is 7V. Is there any other opamp for this application?
I am using Vref as 2.5V, How I can give bipolor +/-5V using OPA350.

Any one pls explain this circuit?

Regards,
Hamdan[/img]

 

[DuDepp]

Hallo Hamdan,

your circuit produces 0-5 V at the ADS1252 from a ±5 V input. The OpAmp 2350 is a rail-to-rail type. So from 5 V power supply it can produce 0-5 V output.

Function:
Lower OpAmp makes a stable Vref of +2.5 V for the ADS1252.

Input +5 V: This results in 3.33 V at the + input of the upper Opamp. To get the same voltage at the minus input the output goes to +5 V.

Input -5 V: This results in 0 V at the + input of the upper Opamp. To get the same voltage at the minus input the output also goes to 0 V.

All other input values produces a voltage between these two limits.

Regards

DD

 

[hamdan]

Hi DD,

Thanks for your explanation. I need some more explanation.
In the datasheets, they have given as need to separate the analog and digital Ground. If the OP amp side is analog side, then which is the Digital GND?
Is it the 5V powersupply GND? Now I have used a common Ground. Is there any problem?

The Bipolor +/-5V comes from a opamp output (the positive input is Grounded and the feedback resistor connected between the negative input & output). So Do I need to choose a opamp with power supply V+ 5V and V- -5V? So I cannot use OPA350, am I correct? Which opamp can you recommend? Thank you.

Regards,
Hamdan