We have 8 x GPIO from Microcontroller which need to be connected at a remote location which is around 8 to 10 meters. The load current is something around 25 mA per GPIO. Kindly suggest line buffer/GPIO buffer that can be used with the Microcontroller board which we need to design. It is important that there should be no I2C. Just a simple parallel in parallel out.

 

There are hundreds of different devices, all with different specifics. Have you researched exactly what you need?
Example: https://www.onsemi.com/products/tim...ic/buffers/mc74act541#technical-documentation

 

Have you considered RS-485 transceivers. I know that may sound redundant, but you'll only have to stock one part for driver and receiver.

 

The application is that we need to control Relays which are located remotely on Relay board. The switching of Relay is slow. The Relay boards are located around 8 to 10 meters away from Microcontroller. Therefore, we are looking for single ended I/O buffer IC.

I will look at 74ACT244, 74LVC244 and also MC74ACT541.

 

The load current is something around 25 mA per GPIO

Hi eng.
Are you driving the remote relay coils with the required buffer outputs?

E

 

The application is that we need to control Relays which are located remotely on Relay board. The switching of Relay is slow. The Relay boards are located around 8 to 10 meters away from Microcontroller. Therefore, we are looking for single ended I/O buffer IC.

I will look at 74ACT244, 74LVC244 and also MC74ACT541.

Those are all meant for driving singnals on a board at high speed. They are not designed for the load of a long cable. Do you not understand the difference?

 

Hi eng.
Are you driving the remote relay coils with the required buffer outputs?

E

Yes true.

 

Those are all meant for driving singnals on a board at high speed. They are not designed for the load of a long cable. Do you not understand the difference?

I am sorry. I am not getting.

 

hi eng,
Is this buffer is an option.

A simple sketch would help us, help you.
E

 

This is darlington configuration in which two transistors are in cascade to increase the current.

I am not sure why it state "sink driver".

 

Hi,
Post a sketch.
E

 

This is darlington configuration in which two transistors are in cascade to increase the current.

I am not sure why it state "sink driver".

That is because it can "sink" more current in the "low" state than it can "source" in the "high" state.

 

I am sorry. I am not getting.

I know you are not getting it. In simple terms a line driver and receiver are DESIGNED to overcome the signal integrity problems of sending and receiving data over long cables. They do this with differential signaling which overcomes problems with signal integrity and ground referencing inherent with single ended signaling. RS-485 devices ARE designed for reliable signaling over long cables. Can the RS-485 receiver drive the relay coil directly? I don't know but you can probably figure that out from the datasheet or run the experiment.

 

For 'relay' driving, the ULN2803 is what I commonly use on 3.3V controller boards.

 

Nothing prevents you from using RS-485 transceivers to move the data across the cable and THEN using the ULN2803 to drive the relay coils. In my mind that would be an elegant solution, solving each of two different problems with an appropriate part. Also note that the RS-485 transceivers may come in dual or quad packages further simplifying the design