The circuit is designed in the figure below, we measured the value of Pin2 is 3.31V; the Pin7 is 3.25V. What effect will Vref1>Vref2 have on the device?
BR, Gary
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.
The circuit is designed in the figure below, we measured the value of Pin2 is 3.31V; the Pin7 is 3.25V. What effect will Vref1>Vref2 have on the device?
BR, Gary
In theory, there should be no voltage difference. It looks as if there is a leakage current of 0.3 µA somewhere.
Anyway, these voltages are OK; the PCA9306 will still work as an I²C switch. (The voltages will be clamped at EN − 0.8 V, but the pull-up resistors take care of that.)
One more question.
If VREF1 = VREF2=3.3V and Ven reach 3.3V, it means that the Vgs voltage is ~0V, which will cause the switch can't turn-on. Is that correct?
BR, Gary
When Vgs = 0 V, then the transistor indeed does not turn on.
However, the figure shows only the reference transistor, which does not matter in this application. There are similar transistors between the other I/Os, and those switch on when the voltage at an I/O pin goes low.
(In this figure, no DC current flows through the 200 kΩ resistor, so you can simply connect EN directly to the lowest power supply.)