OPA4172: OPA4172 replace OP275

Morning Mr. Wang,

The OPA275 is of course a dual - the OPA4172 is a quad, 

Basically looks pretty simple and should work - I do wonder about that mute feature? Really asking output to drive into a short via those transistors? It would be more reliable (and lower power) to put those across the 51kohm to ground at the inputs. 

Hello,

I would also recommend showing the customer the OPA2991. The OPA2991 is a new version of our OPA171 (lower BW than OPA172) but it will have less bandwidth and higher noise than the OPA2172. Depending on the design requirements of the customer the OPA2991 may work for them.

What is the purpose of the 10k and 47pF used in the feedback? If they need a buffer configuration I would recommend shorting these components. Typically using a resistor in the feedback of a buffer provides no benefits. I recommend taking a look at this technical article for more information.

Please be sure the customer has included decoupling capacitors for the op amp in their schematic.

Also, as Michael mentioned they would need the dual version (OPA2172) not the quad (OPA4172).

Thank you,

Tim Claycomb

Hi Michael & Tim,

Thank you for the information, I do mentioned the problem of 10k and 47pF to the customer but since the schematic is already tested and is fined then I'll just leave it....

I do mention the 2 and the 4 channel feature to the customer but they want to use OPA4172 for other project and also replace LMV934.

if they insist to use OPA4172, I remember that the unused pin should be configure as voltage follower and remain in VCM range, and I correct?

it should be the most easy way to do~

I will also forward the technical article to them as reference.

Thank you.  

Best Regards 

Evan

Hi Tim,

Thank you for your help.

Best Regards 

Evan