Hi team,
For INA128 (+/-5V supply), when increasing input signals, the output starts reversal. While, in same circuit same condition, when put INA828 on board, the output is not reversal. Output reversal should be caused by input violation, but according d/s of INA128 and INA828, their input CM range is almost same.
Wonder to know what is potential reasons here for INA128 output reverses, while INA828 not?
Thanks,
-Rocky
Hi Rocky,
Thank you for your post. Can you share some more information about your circuit? What is the gain, Vref, Vcm? A schematic would be great.
You mentioned that when increasing input signals, the output starts reversal. Do you know at which voltage level this is at?
The INA128 and INA828 have different Vcm v Vout behavior. This can be shown in our "Common Mode Input Range Calculator for INA" (http://www.ti.com/tool/INA-CMV-CALC)
At +/-5V supply, Gain = 1, Vref = 0, and Vcm = 0, the INA128 has an output voltage swing range of -4.2V to +4.1V:
At +/-5V supply, Gain = 1, Vref = 0, and Vcm = 0, the INA828 has an output voltage swing range of -4.9V to +4.9V:
-Tamara Alani
Hi Tamara,
Gain is 1 (Rg is not connected), Vref is grounded. Here is the circuit.
The front stage amp clamp the voltage at around 6V. Then INA128's output will show phase reversal. But INA828 does not show reversal.
Once disconnect front stage amp with INA, input an external DC source to INA828 directly. Then INA828's input clampped at 5.7V, this should be effect of internal protection diode. And the output is 4V. (of cause this input already violated). Just wonder to know INA828 could clamp the input voltage, what if the limited current is too big? In this test, the input DC source current was limited at 100uA. What if 10mA, 1A? I see d/s the max current is 8mA. How to handle if there is big current when overdrive?
Thanks!
