What is 74HC541PW??

[KansaiRobot]

Hello
I was reading a schematic and I found this chip: 74HC541PW. What is this?
(I am supposing this is the same as 74HC541)
I found the datasheet:
**broken link removed**

It says it is a "octal non-inverting buffer/line driver with 3-state outputs".... what???

Can someone explain this in simpler words?

Reading the schematic, it seems it is something to change level voltage?? You see, the schematic is this one:
**broken link removed**

and there, by putting say 3.3V to 74HC541 Vcc, the 5V signals (from an arduino ) can be changed to 3.3V signals for a LCD
and vicecersa, by putting 5V to Vcc the 3.3V signals of the LCD can be converted to the required 5V signals (of the arduino)

Is this correct???

thanks a lot

 

[Les Jones]

As the description says it is 8 non inverting buffers with tri state outputs. This means that the output pins can be low, high or open circuit. they are normally used as bus drivers on a computer system for example. Only one device can transmit on a bus at one time so devices not selected are in the tri state condition so they do not load the signal from the selected device.

Les.

 

[KansaiRobot]

As the description says it is 8 non inverting buffers with tri state outputs. This means that the output pins can be low, high or open circuit. they are normally used as bus drivers on a computer system for example. Only one device can transmit on a bus at one time so devices not selected are in the tri state condition so they do not load the signal from the selected device.

Les.

Thank you very much for your reply.
"8 non inverting buffers with tri state outputs"
Ok, starting by the "tri-state outputs", ok got it, the output can be high impedance... However I suppose you do this by enabling or disabling the corresponding pin but as you can see this pin is always enabled (set to ground) so I guess in that schematic this property is lost. Isnt it?

How about the rest.? I got the "non-inverting", I suppose it means the signal goes as it enters. and the octal part I suppose it is because it has 8 inputs and outputs...

but what about what is not written in that definition? I mean what I asked in the first post? Does this chip works as voltage changer? From 3.3V to 5V and vicecersa? because that is what it seems in the schematic... Some are powered by 5V and some by 3.3V according their functions...

 

[JimB]

In the NXP overview there is a statement:

Inputs include clamp diodes that enable the use of current limiting resistors to interface inputs to voltages in excess of VCC.

Which means that if the '541 had a supply of 3.3volts, the inputs could be from a 5volt system if there were current limiting resistors on the inputs to the '541 from the outputs of the 5v system.

The schematic from elecfreaks.com does no show any current limiting resistors.
This makes me think that it is a badly designed circuit.

JimB

 

[KeepItSimpleStupid]

It says it is a "octal non-inverting buffer/line driver with 3-state outputs".... what???

octal - fancy way of saying 8 of them

non-inverting - fancy way of saying, a high in results in a high out

buffer - more something: Higher current usually

line - they are referring to a "transmission line" or a wire at high frequencies

driver - more something. Might be able to drive longer distances or higher capacitances

3-state outputs or tri-state - Yep, there are three states. Pulled down to Vss, pulled up to Vdd or "disconnected" (fixed per Mikebits)

You can only put all of them in an Hi-Z state use OE1 and OE2. Typical use is a 8-bit data bus.

 

[KansaiRobot]

Thank you guys
Anyway, can the 541 be used for converting voltages?? 5V part to 3.3V and viceversa?

In the NXP overview there is a statement:

Which means that if the '541 had a supply of 3.3volts, the inputs could be from a 5volt system if there were current limiting resistors on the inputs to the '541 from the outputs of the 5v system.

The schematic from elecfreaks.com does no show any current limiting resistors.
This makes me think that it is a badly designed circuit.

JimB

So it can be used for 5V->3.3V (with current limiting resistors), right? How about the opposite? (3.3V -> 5V, providing 5V to the VCC)...



QUESTION: Is this 74HC541 similar to 74HC4050?? But then again the 4050 only goes from HIGH to LOW.... not opposite....

 

[JimB]

How about the opposite? (3.3V -> 5V, providing 5V to the VCC)...

Without looking at the datasheet, it all depends on if the '541 will recognise 3.3v (or whatever the driving device will give) as a logic high.

JimB

 

[Mikebits]

3-state outputs or tri-state - Yep, there are three states. Pulled down to Vdd, pulled up to Vss or "disconnected"

I think your Vdd and Vss are backwards there KISS

 

[KeepItSimpleStupid]

Fixed and credit given - thanks

 

[KeepItSimpleStupid]

The datasheet says high voltage to low voltage translation for the 4050.