Hi All,
I want to use a level shifter, these are really small and hard to work / test with. I have one on a PCB but it's not working as expected. The reason this is not working could be something else and not the level shifter + wiring, so I thought I would break it down into sections. To do this I made a breadboard version of a level shifter using a PNP (2N4403) and a NPN (BC548B) and to simulate I added 22k resistors in the same positions as the . This still does not work but I think this is because the transistors are not 100% the same . If I reduce the NPN base resistor to 10k (was 22k) it works, but this does not help me determine if I have got it right with my BCR22PN level shifter.
The RX_IN in 5v and the RX_OUT it 3.3v on a Xmega MCU RX pin.
So I have a couple of questions:
Thanks in advance
Steve
I want to use a level shifter, these are really small and hard to work / test with. I have one on a PCB but it's not working as expected. The reason this is not working could be something else and not the level shifter + wiring, so I thought I would break it down into sections. To do this I made a breadboard version of a level shifter using a PNP (2N4403) and a NPN (BC548B) and to simulate I added 22k resistors in the same positions as the . This still does not work but I think this is because the transistors are not 100% the same . If I reduce the NPN base resistor to 10k (was 22k) it works, but this does not help me determine if I have got it right with my BCR22PN level shifter.
The RX_IN in 5v and the RX_OUT it 3.3v on a Xmega MCU RX pin.
So I have a couple of questions:
- Looking at my picture should this work as a level shifter?
- Am I correct in saying the my breadboard simulator does not work because of the difference in the transistor specs.
Thanks in advance
Steve
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