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DS90UB953-Q1: Minimum CSI-2 data rate

Jorge Rive
Prodigy 180 points
Part Number: DS90UB953-Q1

looking at the datasheet for the DS90UB953, the minimum MIPI data rate is listed as 80Mbps.  In my application, I am interfacing a low resolution camera whose data rate is about 8.2Mbps.  What drives the minimum data rate specified?  I need to convert the camera's VoSPI interface to CSI-2 (or DSI) so I can interface it to this (or some other) serializer to reduce pin count and improve noise immunity in an automotive application.   I'm wondering if I would have to buffer the data and then burst it to meet this minimum data rate, or if I can stream these images or video at the slower "native" rate.  Is there a more appropriate serializer/deserializer pair to consider for such a slow data rate? 

  • 0
    TI__Genius 11350 points

    Hi Jorge,

    Thanks for your inquiry. We would not recommend operating the DS90UB953 below the minimum data rate listed in the datasheet. Do you have a block diagram of the system which you're designing & details on the sensor which is being used for this application? One lower speed serializer we have available is the DS90UB913A, which can operate at a pixel clock as low as 25MHz. 

    Best,

    Thomas

  • 0 in reply to Thomas Bejin
    Prodigy 180 points

    Hi, 

    I’m trying to interface to a Lepton 3.5 thermal camera. It is a low resolution sensor, which uses a video over spi interface (VoSPI) for Video data, and I2C for control.  The data rate is sbout 8.2Mbps. Because I’m going off board (and a few meters in length), I want to reduce pin count and improve noise immunity using a SERDES, with PoC.  

    The sensor outputs 16bits per pixel (radiometric mode, representing temp in degrees kelvin). 

     I figured I could do the protocol conversion (VoSPI to CSI-2)in an FPGA, and then feed the output to the serializer.  I would have to add significant buffering to enable the bursting of video data to meet the ICs’ specs. But, I don’t understand what  drives the minimum data rate. 

    What recommendations could you provide regarding the interfacing of such a slow data rate sensor to one of your SERDES pairs?

    I can share a block diagram when I’m at my computer tomorrow.

    thank you 

  • 0 in reply to Jorge Rive
    TI__Guru* 98495 points

    Jorge,

    Your proposal to buffer the data and send in bursts to 935 at >=80Mbps is the correct method. You should plan to use 1 CSI-2 lane mode to reduce the buffering needed as much as possible. 

    80Mbps is the slowest speed that the device can lock to and properly recover the CSI-2 clock 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 180 points

    thank you Casey.  Do you have other suggestions regarding  serializer/deserializers better suited for this application/data rates?