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DS90LT012A / FailSafe not working

Kuramochi Tadahiko
Guru 28715 points
Other Parts Discussed in Thread: DS90LT012A

Hi,

Manufacturing failure is happened on the my customer circuit which used  DS90LT012A.

The IN+ pin of the DS90LT012A is opened by this manufacturing failure.

I think that the Failsafe of the DS90LT012A should be worked, however not worked such as following waveform.

Is there any important point on the circuit to work the Failsafe?

Best Regards,

Kuramochi

  • 0
    TI__Mastermind 43795 points

    Hi Kuramochi,

    Thanks for the oscilloscope waveform it helps to understand the issue.  There is significant coupled noise on the IN+ and IN- signal pins (over 1Vpp).  If the scope was setup to apply the Math formula IN+ - IN-  to the signals, there would be a large differential input signal on the DS90LT012A.  The input of the DS90LT012A is just responding to this input.

    Based on the DS90LT012 output IN- is either connected to a 32 MHz clock or a 32 MHz clock signal is coupling onto the input differential pair.

    Regards,

    Lee