Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

74HC595 5V powered & 3.3v input levels

Status
Not open for further replies.
L

limpkin

Newbie level 4
Joined
Mar 22, 2008
Messages
7
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,321
74hc595 3.3v

Hello everyone,

Just a message to know if someone has ever tried 3.3v input signals on a 74HC595 chip (or more generaly a 74HCxxx) 5V powered.
On its datasheet, for a 4.5v Vcc the trigger is supposed to be at 3.15V so I was wondering if anyone in this forum has ever tried.

thanks in advance
 

level traslator 3,3v 5v

You can 't reliably drive a 74HC series device operating on a 5V Vcc with a 3.3V device without a level-translator of some type. It's common for manufacturers to spec the Vih level as 0.7 x Vcc. For a 5V Vcc this gives you a Vih of 3.5V.
 

driving 3.3v logic from 5v

Hi,

What you need is a ' bi directional translator ' chip , if you search your local specialist supplier you should find some, Texas do a range - most seem to be smd, but are hand solderable with care if you get the Soic types.

Heres a selection in my area - the 104 /108 chips automatically select the data direction as well.
https://uk.farnell.com/jsp/search/r...uestid=727330&isGoback=false&isRedirect=false
 

level chip from 3.3v to 5v

Actually I only need an uni directional translator with many inputs, max freq i need is at least 2KHz.
Does someone know a chip like that?
 

74hc 3.3v

Yes, 74HC high input level isn't achieved reliable when driving it from 3.3 V logic.

What you need is a ' bi directional translator ' chip
Click to expand...
Not a well considered suggestion, I think.
- No bidirectional level translation is required
- The usual solution is using 74HCT instead of 74HC devices. They can be driven from 3.3V logic. Alternatively 74HCT buffers can be used as level translators.
 

input has 3.3v high but needs 5v

Actually I didn't chose the 74HC devices... they are a part of the constraints...
That's why I just want a simple solution to adapt 27x 3.3V > 5V signals
 

3.3v - 5v 74hc

O.K., so you may want to refer to my alternative suggestion. 74HCT has a minimum high level of 2.0V.
 

level translators 3,3v 5v

Sorry for my english, maybe I wasn't clear enough.
I must use the 74HC devices
 

3.3 to 5 volt translation

Yes I know. Some level translation is needed anyway.
Alternatively 74HCT buffers can be used as level translators.
Click to expand...
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top