[SOLVED] Question about bi-directional voltage level translator.

[flote21]

Hello guys!

I am planning to use this part: LSF0108 to drive the data bus of the attached display LCD.

I want to use this part like a bidirectional buffer line driver without any voltage level translation (So Vref_a=Vref_b=5V) and the datsheet says that in order to avoid integrity problems, vref_b > Vref_a+1V....

Howerver as far as i am not going to control a high speed bus, I would say that it should not be a problem right?

The reason because I like LSF0108 is because it has not any directional terminal...

Greetings!

View attachment DVF-16210-3V1FBLY.pdf

 

[KlausST]

Hi,

What´s the use of using an "voltage level translator" without voltage level translation function?
I assume i´t working only with external pullup resistors on each ine and each side --> 16 pieces. Don´t use push-pull
Datasheet clearly says: "The LSF family does not provide any drive capability. "

Maybe you are looking for a 74xx245?

Klaus

 

[esp1]

hi,
I read the d/s for the LSF as per the attached clip from the d/s. Cref A = 4.5v max.
E

 

[flote21]

Yes I am looking for something like 74xx245 but with no directional terminal? Does it exist?

Greetings

Hi,

What´s the use of using an "voltage level translator" without voltage level translation function?
I assume i´t working only with external pullup resistors on each ine and each side --> 16 pieces. Don´t use push-pull
Datasheet clearly says: "The LSF family does not provide any drive capability. "

Maybe you are looking for a 74xx245?

Klaus

 

[KlausST]

Hi,

The LSF is not driving a signal actively. It´s a passive device.

You didn´t answer what your circuit is good for. So again we have to guess. Time stealing.

If you want something to drive in both directions actively.
Then imagine as if you have a car witjout gear box. How can the car know wich direction to go?
Or it´s like a pump. You want to drive the fluid in both directions. Without a switch or a valve to set the driection.

--> I don´t see a way.

Klaus

 

[FvM]

As already stated by KlausST, LSF0108 isn't a buffer. It just a number of pass switches limiting the bus voltage in one direction. Effectively a replacement for discrete MOSFET transistor used in this place.

A bidirectional buffer needs some kind of direction control, either external (the usual way) or with a special internal logic determining the signal direction from the signal levels and currents. There are some application specific buffers with automatic direction control available, e.g. for I2C busses. Besides respective higher price for the special logic, you pay a price in terms of performance.

For a parallel LCD bus, the R/W signal allows an easy control of DB data direction. All other signals are unidirectional and don't need direction control.