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DS90UB948-Q1: How to know the abnormal output signal caused by the transient abnormal power failure of the deserializer by monitoring the status of DS90UB948-Q1

liwen hsu
Prodigy 20 points
Part Number: DS90UB948-Q1

1. After the deserializer is configured, as long as there is video, the lock pin is high,

but when the DS90UB948-Q1 is powered on or in use, if the power supply of the DS90UB948-Q1 is momentarily abnormal and the power is off, the output LVDS video signal is a bit abnormal, and the display is abnormal, how can we detect the abnormal situation? The lock pin will not change and cannot be detected through this pin?

2. How to detect whether initialization is successful?

Part of the picture flickers，At this time, power on again and initialize DS90UB948-Q1 to restore to normal.

  • 0
    TI__Guru** 108460 points

    Hello Liwen,

    can you please explain what do you mean by abnormal power supply? Does the Power supply go to off after it is abnormal? Did you measure the power level and noise levels?

    What do you mean by "the output LVDS video signal is a bit abnormal" Did you measure that signal?

    What abnormal situation do you want to detect?

  • 0
    Prodigy 20 points

    Hello,

    1.I mean, after working normally, the VDD of the DS90UB948 drops to about 1.8V instantaneously due to the fluctuation of the power supply on the car and recovers after several hundred milliseconds. At this time, abnormal display may occur, and the entire system needs to be rebooted to recover.

    2.The probability is relatively small. It is difficult to capture the power waveform of the DS90UB948 when the whole machine is installed on the car.The abnormal output signal is caused by the transient power failure, which causes the LVDS differential output amplitude to slightly decrease by more than 10 mv or individual differential pairs have no data output.

    3.During operation, for example, when VDD is powered down to 1.8V and then quickly recovered to 3.3V, can we obtain the exception by monitoring the register status of 948? Could the image phenomenon in the previous post be caused by the DS90UB948's abnormal operation.

  • 0 in reply to Hamzeh Jaradat
    Prodigy 20 points

    Hello,

    1.I mean, after working normally, the VDD of the DS90UB948 drops to about 1.8V instantaneously due to the fluctuation of the power supply on the car and recovers after several hundred milliseconds. At this time, abnormal display may occur, and the entire system needs to be rebooted to recover.

    2.The probability is relatively small. It is difficult to capture the power waveform of the DS90UB948 when the whole machine is installed on the car.The abnormal output signal is caused by the transient power failure, which causes the LVDS differential output amplitude to slightly decrease by more than 10 mv or individual differential pairs have no data output.

    3.During operation, for example, when VDD is powered down to 1.8V and then quickly recovered to 3.3V, can we obtain the exception by monitoring the register status of 948? Could the image phenomenon in the previous post be caused by the DS90UB948's abnormal operation.

  • 0 in reply to liwen hsu
    TI__Guru** 108460 points

    Hello Liwen,

    Thanks for the clarification!

    liwen hsu said:
    During operation, for example, when VDD is powered down to 1.8V and then quickly recovered to 3.3V, can we obtain the exception by monitoring the register status of 948? Could the image phenomenon in the previous post be caused by the DS90UB948's abnormal operation.

    Yes, this is very likely possible. The VDD33 has a tolerance range of 3V to 3.6V. If this voltage drops all the way down to 1.8V then this is a clear violation of the device specs which could lead to anything, from disturbing the input signal to no output on the display. 

  • 0 in reply to Hamzeh Jaradat
    Prodigy 20 points

    copy that，Is there any method to monitor the 948 when it is powered down instantaneously？

  • 0 in reply to liwen hsu
    TI__Guru** 108460 points

    Unfortunately, not!