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THVD1550: power dissipation at RL=220m ohm

Hisao Uchikoshi
Genius 14280 points
Part Number: THVD1550
Other Parts Discussed in Thread: THVD1450,

Hi Experts,

I want to estimate the power dissipation. There is a figure in the datasheet.

I want to know any figure at RL = 220 ohm. I need it for both THVD1550 and THVD1450.

Do you have any data?

Regards,

Uchikoshi

  • +1
    TI__Guru 50795 points

    Hi Uchikoshi-san,

    The figure here shows the increase in supply voltage with data rate due to capacitive losses. This increase is largely independent of what the resistive load is. A different resistor load will change the starting point of this graph (at 0Mbps), but the slope of increase will remain similar to what is shown. The starting current for this graph can be calculated using the DC component of the bus current. In this case with a 54-ohm load, the typical differential output Vod is 2.7V, resulting in 50mA. With a resistor value of 220-ohms, the Vod will be slightly more than 3.0V (estimate from figure 2) which results in a current of around 15mA. 

    While the values for THVD1450 may be slightly different, this process will be the same. Additionally if these calculations are for thermal dissipation calculations, keep in mind that the power dissipation will be split between the transceiver and the termination resistors. 

    Let me know if you have any more questions.

    Regards,
    Eric Schott

  • +1 in reply to Eric Schott1
    TI__Genius 14280 points

    Hi Eric,

    Thank you for your deep explanation. I understood very well.

    Regards,

    Uchikoshi