How to test and check a multiplexer chip?

[danny davis]

How do you test to make sure a multiplexer is working or if its bad, "in circuit" tests?

What are common signs of a bad multiplexer that is not working right or has been damaged?

 

[HTA]

Hi Danny,

the multiplexer function switches X-input signals to one output. To test the function of a digital multiplexer each channel needs to be selected an toggled with a Low and High logic level and the changes can be test on the output. To detect also shortages between the channels the other inputs should have the opposite logic level. If you need to cover all failure modes you have to do an FMEA analysis at the iC-level. Typical signs of a damaged chip are high static supply current or high input leakage(e.g. ESD damage).
Do you want to test an analog or digital multiplexer?

Enjoy your design work!

 

[danny davis]

Analog TTL and CMOS multiplexer chips , how do I test them in circuit please?

 

[HTA]

Can you be more specific? With extern test bead or during start-up with selftest?

Enjoy your test challenges!

 

[danny davis]

Just testing the inputs and outputs of any TTL and CMOS multiplexer chip. I don't know how to test the inputs and outputs when the multiplexer chip is in circuit, how does a tech do this?

 

[HTA]

If not testing circuit is been designed in the only method is to use external needle to contact input and output and override the input signals with an external DC or AC signal. Then see what the output is responding.

Enjoy your test challenges!

 

[danny davis]

only method is to use external needle to contact input and output and override the input signals with an external DC or AC signal

What kind of needle would you use?

How would you override the input signals, using what?

Wouldn't I need multiple function generators or power supply's since a multiplexer has multiple inputs?