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TUSS4440: Vout performace different

Lidong Yu
Intellectual 1756 points
Part Number: TUSS4440

i have issue with TUSS4440 VOUT waveform, as showed in the follow three pictures,

the first one shows the VOUT and O4 output logic when signal in, O4 output triggered when VOUT reach trigger point.

in the follw picture, VOUT has one or more littele delays when signal in, as marked in the red part:

in the follow picture,  the time between start point and trigger point is shorter than the fire picture shows.

all these test are under the same condition.

my question:

1. why VOUT has some delays on the waveform?

and any suggestion on filter the sensor noise?

  • 0
    TI__Genius 12436 points

    Hi Lidong,

    Are these waveforms representing the return echo or the transmit burst?

    The trigger point looks to be functional at the same threshold for each waveform.

    There will be some small error associated with slight differences during the burst waveform, but this will not measurably affect the TOF measurements.

    In summary, I do not see any delay that will cause issue. The Vout waveform will have natural deviations that make it appear slightly different than the others. I have based this determination off of the measured time between Vout start and trigger point.

    Noise can be coupled into the system in many ways. One way to reduce noise could be via adjusting the register settings associated with the BPF. You can adjust the Q-factor of the filter to make the response more aggressive. 

    Please let me know if you have any questions,

    Thank you,

    Jacob