Check Working of IC 74LS147

[Utkarsh_]

How to check if ic 74ls147 is working properly?
I have this IC. After reading the datasheet, i gave the input corresponding to the truth table. However, I am not able to get the desired output. Output is showing high always
I know this is a Binary to BCD encoder IC. I just want to test weather the IC is giving proper output.

 

[betwixt]

If you have a logic analyzer, connect it to all the inputs and outputs and you should be able to see it in operation.

Otherwise, your only option is to remove it from circuit and build a test rig for it. For simple logic functioning, use LEDs with 270 Ohm series resistors from each output to ground and tie all the inputs low with 470 Ohm resistors. If you then short each input combination to +5V you should see the corresponding binary output for the input you shorted.

If you want to do dynamic or parametric testing, you need a signal source and oscilloscope capable of resolving the rise and fall times of all the signals
and delays between them.

Brian.

 

[Utkarsh_]

What will happen if I don't connect input low with resistors? Like If I just connect connect them to ground without resistors?
In this case, current will be high through IC. Will it effect the working of IC?

 

[betwixt]

Grounding the inputs will not cause excessive current, it's how they are supposed to work. The reason I suggest adding resistors is it keeps the inputs at logic low state (all '0') so it's easier to visualize the binary output but still safe to short the inputs to +5V without the resistors passing too much current. The inputs will default to high state (all '1') if you don't pull them down but that makes the binary conversion harder to follow and also makes it prone to picking up noise.

If you want to avoid resistors, just connect the inputs directly to ground or +5V but do not leave them disconnected.

Brian.