CSD87335Q3D Datasheet, PDF (14/23 Pages) Texas Instruments – Synchronous Buck NexFET Power Block

CSD87335Q3D
SLPS574 – FEBRUARY 2016
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Calculating Power Loss and SOA (continued)
In the design example above, the estimated power loss of the CSD87335Q3D would increase to 2.14 W. In
addition, the maximum allowable board and/or ambient temperature would have to decrease by 1.81ºC.
Figure 33 graphically shows how the SOA curve would be adjusted accordingly.
1. Start by drawing a horizontal line from the application current to the SOA curve.
2. Draw a vertical line from the SOA curve intercept down to the board/ambient temperature.
3. Adjust the SOA board/ambient temperature by subtracting the temperature adjustment value.
In the design example, the SOA temperature adjustment yields a reduction in allowable board/ambient
temperature of 1.81ºC. In the event the adjustment value is a negative number, subtracting the negative number
would yield an increase in allowable board/ambient temperature.
Figure 33. Power Block SOA
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