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Absolute Maximum Voltage in OP4177

Question asked by cheski on Jan 27, 2015
Latest reply on Jul 10, 2015 by cheski

Hello everybody,


First of all, thank you for your replies, as this is my first post in this Comunity.


I have an Analog Input to measure the output signal (in current) of a HV transducer. The transducer is suplied to +- 24V

The Analog Input consists on:

- TVS of Vbr=15V

- An array of resistors to become the current into voltage.

- A buffer with Op. Amp. OP4177 in Sallen Key configuation (1 stage). The supply of the Operational is bipolar and suplied to +- 12V


My problem is that, when a transient overvoltage hapens in HV section (this, in theory should not happen, but it does), the voltage in the AI goes avobe de 15V of the TVS; and after many transient overvoltages, the TVS goes into continious low impedance. This is fine, as it protects the OA, but I need to reduce the number of permanent failures of this stage.


So, my question here is:

Can I increase the Vbr level of the TVS to 24V  without risk of breaking down the OA? If not, I need to add some alternative protection to reduce the permanent failure rates. Any Ideas?


I attach you the AI stage and de Absolut Maximum Ratings of the OP4177.


Thank you for your help.