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Design >> High-Power Design >> Thermal Considerations
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Message started by raja.cedt on Jan 24^th, 2013, 11:35am

Title: Thermal Considerations
Post by raja.cedt on Jan 24^th, 2013, 11:35am

Hello all,
I have two current mode driver's with certain swing @ 50ohm. But one driver taking 20mA from 1.2v and another one drawing same 20mA from 1V (i have same swing in both cases). So my Question is which driver dissipates more heat(heat from driver will be changing characteristics of Optical modulator). Is heat dissipation depends on current drawn by driver or power drawn by driver.

Thanks,
Raj.

Title: Re: Thermal Considerations
Post by Dave Jackson on Jan 25^th, 2013, 11:37am

Hi Raj,
Treat the two drivers (with their respective loads) as black boxes. Pretend that you know nothing else about the drivers other than that one has 1.2V applied across it and the other has 1V applied across it. Since they draw the same current, the driver/load combination with 1.2V will dissipate more power (24mW) than the driver/load combination with 1V across it (20mW). Now think about the loads. Since the two drivers have the same output swing into identical loads, the two loads dissipate the same power (xmW). Subtract xmW from both 24mW and 20mW, and you find that the driver with 1.2V across it still dissipates the higher power. Your driver with 1.2V across it is less efficient (or is being used in a less efficient way) than your driver with 1V across it.
Hope this helps,
Dave

Title: Re: Thermal Considerations
Post by Erez_Sarig on Feb 7^th, 2013, 1:17pm

Heat = Power