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MAX232E: MAX232E Elucidation of failure causes

Arisa Yato
Prodigy 10 points
Part Number: MAX232E

HiGrinning

I am using an MAX232E in a motor control application. between controller and motor.

 

The block diagram of the product is shown below.

Some users are having trouble with MAX232E failure.

Both the motor side and the controller side will fail. The probability of occurrence is higher on the controller side.

Failure mode does not output TX.RX is normal.

CH1:14pin(DOUT1) CH2:DIN1

After investigating the fault, I found that the Vs-(6pin) was not functioning properly.

case1:not work

case2:positive voltage

case3:Voltage instability at output

 

The cause of the failure that I presume is the following, but the failure cannot be reproduced.

1.The GND line is disconnected and the power supply voltage is being applied to the IC.

2.Failure due to surge noise from motor.

3.Damage from ESD

Also, when a failure analysis was performed by a third-party organization, internal destruction of pins 14(D1out) and 15(GND) was confirmed.

Vs-(6Pin) is broken in short mode.

If anyone knows the cause or has experienced similar symptoms, please let me know.I will provide any information you need.

  • 0
    Guru 317390 points

    The most likely cause is overvoltage, i.e., motor noise or ESD.

    The block diagram does not show any protection components. Are there TVS diodes or something like that?

  • 0
    TI__Guru 52462 points

    Hi Arisa,

    Is there any protection on the DOUT/DIN lines? such as external protection diodes. This does seem like an overvoltage even that damaged the device - it most likely is a transient issue that will make it harder to recreate the issue. The noise from the motor could be inducing transients in the system. I'd highly suggest placing protection devices on the line in motor control applications.

    Please let me know if there is protection on this line.

    Best,

    Parker Dodson

  • 0
    Prodigy 10 points
    Thank you for answering.
    I was able to solve and reproduce the problem through experimentation.
    As a result, it broke down due to disconnection of the GND line and noise mixed in from the power supply line.
    Since we left noise countermeasures to the protection circuit inside the MAX232E, we will consider countermeasures using diodes, varistors, etc.
    Thank you very much.