CD4051B: Possible reasons for failure of CD4051

Manu Chang

Intellectual 2020 points

Part Number: CD4051B

Hi,

My customer is facing a problem when using the CD4051 with 3.3V supply, when X3 pin is connected to GND, all the other channels X1-X7 is pulled down to low. The internal short circuit of X3 to other channel may cause this scenario.

Schematic and waveform is as following, 1st channel is output Y when X3 is connected to GND, other 3 channels are channel selection pins. Y has a pull up resistor, which is not drawn in this schematic.

Customer's question is: What reasons may cause to this kind of failure of IC when using 4051, so that they can prevent in future using?

Thanks.

over 3 years ago

0 Tyler McGuire over 3 years ago

TI__Expert 3515 points

Hi Manu,

What voltage are the signals being input on the other channels (X1-X2, X4-X7) while X3 is grounded? Are the channels being floated? A waveform capture showing the input and the output signals would be helpful.

The CD4051B is not internally shorted and this behavior may indicate that the device has been damaged at some point.

Thanks,
Tyler

0 Manu Chang over 3 years ago in reply to Tyler McGuire

TI__Intellectual 2020 points

Hi Tyler,

Thanks for your quick response. All other circuits are floating when X3 is grounded, X1-X7 are either floating or connected to GND, only one pull up resistor is connected to 3.3 V at the output pin Y.

Customer have already been sure about that something may cause the internal damage of CD4051.

So they would like to ask that what can cause this damage when using CD4051, because the schematic seems not that complex.

Hope that you can give us some advices on this, thanks again.

Regards,

Manu

0 Clemens Ladisch over 3 years ago in reply to Manu Chang

Guru 317080 points

The most likely cause is overvoltage.

The schematic shows that the I/O pins are connected to user-accessible buttons without any ESD protection.

0 Tyler McGuire over 3 years ago in reply to Manu Chang

TI__Expert 3515 points

Hi Manu,

As Clemens mentioned, an overvoltage event would likely be the cause. Please refer to this application note explaining some common overvoltage cases: Protection Against Overvoltage Events, Miswiring, and Common Mode Voltages

Thanks,
Tyler

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CD4051B: Possible reasons for failure of CD4051