SN74CBT3251: Failure Analyze for SN74cbt3251

Hi Songzhen,

To help debug, can you provide details on the following:

• When you say failure rate of 2%, can you specify what is failing - are you not getting any output, is it not performing the switching?

• Can you share scope capture at Inputs and output?

• What is your input signal voltage  on B2-B8?

• Could you also check what does the signal look like if you remove the mux and short the signal path?

• Have you replaced the switch with new IC -What result do you see?

Regards

Saminah

Hi Saminah,

See the update below:

B2~B8 is not input in this application, when internal switch is close, the current is flow to B2. The voltage on A is changed.

When you say failure rate of 2%, can you specify what is failing - are you not getting any output, is it not performing the switching?

Failure scenario:

B1 is NC and B1 is good all the time.

Several Pin of B2~B8 were shorted to ground randomly，the maximum number of damages is 4.

The switching performance is wok well.

Can you share scope capture at Inputs and output?

the yellow one is the input signal of B2, The output is flow the input.

the pink one is the trigger signal of S0.

What is your input signal voltage  on B2-B8?

B2~B8 is not input in this application, see the picture below.

Could you also check what does the signal look like if you remove the mux and short the signal path?

If we remove the MUX, it's a resistor net.

Have you replaced the switch with new IC -What result do you see?

Yes. after change the IC,  it works well.

BR

Songzhen Guo

Saminah,

This is the action customer did:

At first, take one failure board, the SN74CBT3251 is damaged;

Then, we remove SN74CBT3251, B2 is shorted to GND;

After that, take a new Sn74CBT3251, slot new SN74CBT3251, this SN74CBT3251 is work well

Customer don't try several new IC. They want to know why SN74CBT3251 was damaged on board.

Could you review this circuit for customer? I have several question for this circuit:

Is the current flow right?

Is SNCBT3251 a bi-direction device?

What's the switch model in side? Is there any risk for this circuit? Can it cause voltage glitch on B2~ B8？（Because B1 is NC, and B1 no damage);