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Balanced line for TLC5970

jiwoo bong
Prodigy 100 points

Hi, 

 

 

It uses some balanaced line for long distance. 

 

But I have no idea which one would be the best suitable among rs422, rs485 and LVDS. 

 

Datasheet recommends -7 ~ 12v so it's rs485 spec. but it's not telling me specific method.

 

I heard LVDS is faster than rs422,485 but a bit more noisy for long distance. 

 

 

I'm thinking up to  10meters.  ~ 15meters at some points of chain not every node. 

 

There are a few high speed rs422,rs485 drivers as well. 

 

 

Please help me.

 

Thank you in advance.

  • 0
    TI__Guru 65170 points

    Jello Jiwoo,

    TLC5970 uses differential input signals to make sure that noise is cancelled for long distance connection. Which type of differential signal you are using depends on your requirements. LVDS is for sure faster as the other 2, but also more noise sensitive.

    E.g. The minimum output threshold voltage of the SN65LVDS31 driver is 247mV which means you have a signal to noise ratio of 47mV. This is high enough for TLC5970 to work with SN65LVDS31 as long as you make sure that the distance between the driver and TLC5970 is not too long (less than 47mV loss in the lines) and the noise is low enough that TLC5970 still can work with SN65LVDS31.

    So for noise immunity the other protocols are better because of the better signal to noise ratio.

    What is the maximum transfer speed you need to get the data fast enough to the last TLC5970 in the row?

    Best regards,
    Brigitte