Other Parts Discussed in Thread: SN74ACT240, SN74LV240A
Tool/software:
Dear,
Is it possible to receive the internal schematic/block diagram for SN74ACT244 and SN74ACT240, included the diodes?
Because we are facing a leakage on the VCC pin: it should be 0V but we can see a voltage of approximately 4V.
Below you can find an oscilloscope image, pink trace is the 5V power supply and orange trace is the 5V supply of the SN74ACT24x (there is a mosfet between them to cut the power). After 5 seconds 5V supply of the SN74ACT24x is enabled and we can see the correct voltage.
Both SN74ACT244 and SN74ACT240 have pull up (10k resistor) on the enable pin (pin 1 and pin 19) to 5V supply that is always present
SN74ACT240 has also 10k pull up resistor at the output pins to 5V supply that is always present.
Our idea is that the leakage comes from either of the 2 pull up scenarios, but in the datasheet we cannot find any information about the internal diodes
Best regards
Alessandro
