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Hi,
Customer board is using OPA725 for battery ADC purpose as below. When both V+ & V- are 0V, they found the voltage level of IN+ is around 0.62V. We'd like to ask, when V+ is 0V(not supplied), what is the impedance of IN+ & IN-?
Thanks!
Antony
Hello,
There are internal ESD diodes from each input to the supply pins (V+ / V-) which are conducting when an input voltage is applied while the supply pins are connected to GND.
There are very few modern products without this ESD cell architecture so the best option will be to prevent the input signal from reaching the IN+ pin of the amplifier while the V+/V- pins are connected to GND, or to place a large resistor in series with the IN+ pin so the input current is minimized.
The LM358/324 are some of the few high voltage products that do not include ESD cells to V+.
Hi Collin,
THanks for your reply. Do we have any part like LM358/324 (do not include ESD cells to V+) but have the same pin definition and package as OPA725? It seems not, right?
Antony
Hi Antony,
Are you looking for pin-to-pin compatibility on the 8-pin SOIC or the 5-pin DBV package?
-Paul