I wanted to follow up on question asked in the link below. In the answer to this question, comments were made about the implications of not meeting the LTC6957 input common mode voltage specification. It was mentioned that the input diodes could clip if the input common mode range specs were not met, and this could cause variation in tpd. I would like to better understand what the implications are of not meeting this common mode voltage specification. For example, if operating with 1.6V or 1.7V common mode rather than minimum 1.8V, would that really cause any difference in operation of the part?
- Now that it's close to two years later, does ADI have any additional information on performance degradation associated with not meeting the common mode input voltage specification?
- Can you clarify comment about diode clipping if input common mode voltage range is not met? What would be the diode conduction path in the image you showed?
- It looks like there are back to back diodes between IN+ and IN-. I understand these would clip the signal if the input differential voltage is too large, but would not seem related to common mode voltage specification.
- It looks like there are diodes clamping IN+ and IN- to VCC (3.3V) and to GND. I think these would prevent inputs from going above VCC or below GND.
- I am not seeing how these diodes would clip the signal if violating the input common mode range unless this caused the input signal to go above VCC or below GND.
- Would it be right to state the diodes would not clip the signal, even if violating the input common mode specification, unless the signal went above VCC or below GND?