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DS90UB935-Q1: Clocking Modes, FC DATA RATE and CSI Bandwidth : f x 160, 80, 40, 28

Dustin Yim
Expert 4096 points
Part Number: DS90UB935-Q1

Hi Experts,

From the data sheet, we can see the "Table 7-6 Clocking Modes"

There are FC DATA RAE & CSI Bandwidth  value for each mode. But I am not able to understand where is the value come from?

I mean f x 160, f x 80, f x 40,/ , f x128, f x 64.

Could you please give me an explanation about it?

Thank you.

  • 0
    TI__Mastermind 25171 points

    Hi Dustin,
    Thanks for your inquiry. The DS90UB935 has several different modes which are detailed in section 7.4 of the datasheet. The mode is selected based on the bandwidth required for this particular application, partner deserializer selected, and system architecture. When the reference clock is received by the 935, it's used internally within the device feeding into the various PLLs which serve as internal clocks for the 935 generating the forward channel.

    The difference between the forward channel (FC) rate and CSI bandwidth is due to the overhead of FPD data within each data frame. The DS90UB935 formats incoming data into a 40 bit FPD frame, with 32 of those bits consisting of CSI data. Note that the values in table 7-6 are not correct for the 935, and should be lower to correctly indicate the max FPD rate of 3.16Gbps & max CSI data rate of 2.528 Gbps when using a 26Mhz referance clock.  This should result in the CSI bandwidth being ~97*refclk and FPD rate being ~121*refclk. This will be updated in the next revision of the 935 datasheet.

    Best,

    Thomas