DP83848I: power rating of bias resistor (49.9ohm of TD+/-)

Yasushi Fujiwara

Part Number: DP83848I

Hi Experts,

I would like to calculate power consumption of 49.9ohm of TD-pin bias resistor. So I would like to understand a following application note.
http://www.ti.com/lit/an/snla089b/snla089b.pdf

The table 3 in application note, p6, I suppose Tct is a current through VDD(+3.3V) to bias resistor(49.9ohm). Is my understanding correct? If so, it should use 1/4W resistors, correct?

[example]
- Worst case;
Ict=61.55mA, Rbias=49.9ohm,
Pdiss = Ict^2 * Rbias = 189mW

Best Regards,
Fujiwara

over 6 years ago

0 Hung Nguyen92 over 6 years ago

TI__Expert 5670 points

Hi Yasushi,

See figure 7.2 of the datasheet for the MDI connection. The CT current does not necessarily go thru the termination resistors.

Regards,

Hung Nguyen

0 Hung Nguyen92 over 6 years ago in reply to Hung Nguyen92

TI__Expert 5670 points

Hi Yasushi,

I haven't heard from you. I’m assuming you were able to resolve your issue. I will go ahead and close this thread.

If you need further support, kindly open a new thread.

Regards,

Hung Nguyen

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DP83848I: power rating of bias resistor (49.9ohm of TD+/-)