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.
I have a transimpedance amplifier (TIA) operating at ±5V supply rail whose output feeds into a LMV7235 comparator. An issue arises when the output of the TIA undershoots momentarily to the negative rail which violates the input common mode voltage range of the LMV7235 comparator. The comparator responds by pulling this node down to about -1V for 14ms. I'm okay with this behavior since the TIA is only being used to modulate the comparator ON or OFF but the datasheet for this comparator states that this will result in an increase of input bias current.
My question is how much will the input bias current increase by and if there are any reliability issues with operating the device in this manner?Thanks, - James
The inputs have ESD protection diodes on the inputs to the supplies. Pulling the input below V- will cause the diode to clamp to V-. The clamp will start conducting about 500mV below V-.
As long as you limit the current to below Abs Max (recommend < 1mA), there should not be a problem. Adding a series resistor will limit the current. So you want a minimum of 5V/1ma = 5k series resistor in line with the input.
If this is expected to happen often, then an external Schottky clamping diode is recommended as the ESD diodes are not really designed for continuous use.
TI Comparators (CMPS) Applications Group
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 Paul Grohe:
In reply to Jim Y:
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.