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DS90CF384A For using only three LVDS data channels issues

Mickey Zhang
Genius 12080 points
Other Parts Discussed in Thread: DS90CF384A

Hi Team,

The customer wants to use  DS90CF384A.  From data sheet it is clear that DS90CF384A is gives parallel 28 bits of CMOS/TTL data.

But In the customer's application he needs an option to use only three LVDS data receiver channels to get  21 bits of CMOS/TTL data. In datasheet, there is no evidence regarding this.

Q1: Can you please let me know if this kind of usage is correct. If this usage is correct, which pins are the output pins when the input pin is RXIN0?

Which pins are the output pins when the input pin is RXIN1? 

Which pins are the output pins when the input pin is RXIN2?

Which pins are the output pins when the input pin is RXIN3?

Q2: If this usage is correct, how to deal with all un-used pins?  Should be pulled down all un-used pins?

Thanks,

Best Regard

  • 0
    TI__Mastermind 23556 points

    Hello Mickey,

    A1: Yes it is possible to use the DS90CF384A as a 21 bit parallel transmitter. This can be done by leaving RxIN3 unconnected (4th LVDS Channel), this is because the least significant color bits will be mapped to this LVDS Channel.

    A2: 

    On the Rx Side:

    The customer can connect a 100-ohm resistor across the positive and negative polarity inputs of the RxIN3± channel and leave this channel unconnected to signal inputs. No additional pull up or pull down resistors are required but surface mount resistors are recommended to avoid the additional inductance that accompanies leaded resistor, also if the customer were to implement this, make sure to let them know to place the resistors as close as possible to the receiver input pins to reduce stubs and effectively terminate the differential lines.

    On the Tx Side:

    Pins RxOUT27, RxOUT5, RxOUT16, RxOUT17, RxOUT10, RxOUT11, and RxOUT23 will be left unconnected. It is not required to pull up or down these pins.

    I hope this helps,

    Andres Blanco