Hi everyone!

I'm working on a project using an Arduino micro controller which outputs 5v at each pin. The components which I will be controlling require 3.5v. The project also requires more control lines than this micro controller has so I will be using a shift register (74HC595) to expand the outputs. Rather than using voltage dividers I was hoping I might kill 2 birds with one stone and just supply 3.5v to the VCC of the shift register. I've done some tests, and this seems to be working as hoped.

Does anyone foresee any issues with supplying 3.5v VCC and 5v to the Data In, Clock and Latch pins?
Should this consistantly output 3.5v to all active output pins?

I've read through the datasheet and both voltages are within spec but I'm unsure what effects mixed voltages might have.

Many Thanks
David

 

Hi David,
Welcome to AAC.
I use these level shifters, they work OK.
https://www.ebay.co.uk/itm/4-channe...h=item5d5f0368cf:g:E38AAOSwn4da31kF:rk:3:pf:0

E

You can also use this IC, add input resistors, say, 100R. Read the 1st paragraph on the PDF.

 

Should be just fine. From the datasheet: "Inputs are overvoltage tolerant allowing them to go as high as 5.5 V at any valid V CC"

 

Hi David,
Welcome to AAC.
I use these level shifters, they work OK.
https://www.ebay.co.uk/itm/4-channe...h=item5d5f0368cf:g:E38AAOSwn4da31kF:rk:3:pf:0

E

You can also use this IC, add input resistors, say, 100R. Read the 1st paragraph on the PDF.

Thanks for the suggestion. I've seen these before and they seem to be highly reccomended for such things.

 

Should be just fine. From the datasheet: "Inputs are overvoltage tolerant allowing them to go as high as 5.5 V at any valid V CC"

Thanks for the clarification!

Will post again if I run into any issues.

Many Thanks
David