This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
OPA192: OPA192 Input Protection Diodes
Part Number: THS4531
Hello all,I have a requirement for my analog inputs to protect it against overvoltage up to 60V.The continuous input current in THS4531 is 10mA so can I put a series resistor to limit the current in 60V overvoltages?The required gain is 0.5V/V
So can I put these resistorsRg=7.5k (0.5W)Rf=3.75kIf I want to use a smaller resistor in input can I use :Rg=15k (0.25W)Rf=7.5kRf is some kind of big then do you think if it is acceptable?Best regards,
While this may help with your input current limitation, you will still need to be wary of exceeding the input pin ratings of (VS–) – 0.7 to (VS+) + 0.7.
We are glad that we were able to resolve this issue, and will now proceed to close this thread.
If you have further questions related to this thread, you may click "Ask a related question" below. The newly created question will be automatically linked to this question.
In reply to Hasan Babiker31:
Then what is the purpose of internal protection diode?
It does not make sense to me. If we limit their current they should not burn meanwhile we are safe.
can you show a schematic?
In reply to Mehran:
The first set of R's should be adequate to protect the current into the input pins for 60V input. That spec is set by the ESD steering diodes from each pin up and down to the supplies. You do need to be a little careful about losing phase margin due to input C and the feedback network, I tried to explain all that in this designing attenuators article,
In reply to Michael Steffes:
Thanks, Michael,Can I always consider that there is a protection diode on the inputs when I see the absolute maximum input voltage as below?Vin max = VS(+) + 0.2 V or 0.7V and VS(-) - 0.2 V or 0.7VI think this 0.2V or 0.7V implies on the presence of diode, isn't it?Best regards,Mehri
This is correct, the 0.7V limit on the abs max implies diodes on the pins. I would not recommend thinking of these as protection diodes though as these are diodes aren't designed to handle continuous currents greater than 10mA (as shown in the abs max). The diodes are designed for ESD signals, typically meant for higher currents in the range microseconds or less.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.