Electronics > Beginners
Logic Level Shifters?
(1/4) > >>
theatrical scene:
I'm working on a project which uses 3.3V from a Raspberry pi with 5V peripherals. I only need to send/receive data in one way (so the logic level shifter wouldn't have to be bidirectional). I'm choosing between these two parts: http://www.ti.com/lit/ds/symlink/cd4050b.pdf and http://www.ti.com/lit/ds/symlink/txb0108.pdf.

Is the latter component overkill for simple digital IO conversion? I assume a standard buffer like the first component would be able to shift up signals if I supplied 5V to VCC with a 3.3V input signal but the data sheet has no mention of this and rather highlights the 4050B's use as a 'high to low' shifter as opposed to low to high. Is my assumption valid or am I missing something?

Cheers
oPossum:
CD4050 is only for 5V to 3.3V (74AHC series can also be used). For the other direction 74HCT series parts can be used, such as 74HCT244 and 74HCT125.
theatrical scene:
Low bandwidth (around 20KHz), delay budget not too critical, no restrictive cost requirements (within reason), bus width of 6-8.
Mr.B:
When I am level shifting I2C (bus width = 2) I simply use a couple of cheap FETs and a few resistors.
Dead simple.
Google *FET level shifter*
theatrical scene:

--- Quote from: oPossum on January 22, 2019, 12:28:22 am ---CD4050 is only for 5V to 3.3V (74AHC series can also be used). For the other direction 74HCT series parts can be used, such as 74HCT244 and 74HCT125.


--- End quote ---

Thanks for that, will have a look. The RPi has uses both inputs and outputs which means I would need to get both the 74HCT and 74AHC parts right (for low-high level shifting and high-low)? Would it make it easier to just use a single bidirectional converter like the TXB0108 even though my signals are unidirectional (i.e. either outputs or inputs)? 
Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod