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DS90UB913A/914A

Kikuo Mita
Intellectual 2515 points
Other Parts Discussed in Thread: DS90UB913A-CXEVM, DS90UB914A-CXEVM

Hi team,

Please advise me on the following questions.

Q1. On page 59, Figure 46 shows the allowable loss curves and EQ gain curve.
       Can you explain why allowable loss curve of the STP is 3 dB higher than those Coax?
       Why the allowable loss is 3/6 dB higher than EQ curve?

Q2. Do you know any smaller size coil than L3/L1 (COILCRAFT_KA4909-NO-STUFF) on the EVKs(
        DS90UB913A-CXEVM & DS90UB914A-CXEVM).  (Smaller than WxLxH 5x5x3 mm)
       When you chose alternative coil, can you let me know the characteristics you need to focus?

Q3. When you use a STP cable to transfer power and signal, can you transfer power using only
       differential pair instead of Differential pair and Shield?
       (The DC 12V is connected to DOUT+ and return power is connected to DOUT-)
       If it is feasible, can you provide me a reference schematic to implement such configuration?

Mita

  • 0
    TI__Genius 13475 points

     

    1)      The signal seen by the deserializer is 2X the size if STP is used relative to coax cable, and this accounts for the 3dB difference.   There are second order effects as well – so at higher frequencies, the actual difference is slightly less since the loss for STP is greater at higher frequencies, so once the datarate gets higher, coax becomes a more attractive option.

    2)      The coil size is largely determined by the amount of current being sent to the camera.   The coil needs to be able to pass the DC current required without saturating the core.  By going to a higher voltage POC, and decreasing the current, you will be able to find a smaller size coil that should work. 

    3)      Yes, you can transfer the power on just the twisted pair, and not use the shield – the principle is the same as for the POC.   The disadvantage is that you need the inductive isolation circuit on each of the conductors for the twisted pair, so it increases the number of inductors – which as you note are physically large.

  • 0 in reply to Mark Sauerwald88474
    TI__Intellectual 2515 points

    Mark-san,

    Thank you for the answers.

    Mita