LT8708 How to estimate the NMOS power in Buck-boost mode

Question

Hi team, 
 
 My client cares about heat around MOS when using the LT8708. 
 I want to estimate the power of 4 MOSs from M1 to M4. 
 As explained in the application information of the data sheet, the formula is either Buck or Boost. 
 What is the formula in Buck-Boost mode? 
 
 Assuming a forward direction of 12V to 12V. 
 
 Best regards, 
 T-yoshi

ADIApproved · Accepted Answer

Hi T-yoshi-san, 
 Buck-boost mode has the lowest efficiency as shown in the plot on page one of the datasheet and therefore the greatest total power dissipation. In buck-boost mode, some percentage of the time it is in boost mode and the remainder of the time it is in buck mode. Each FET must be able to handle the worst case situation for that particular FET (buck or boost and forward current or reverse current). The table makes it clear which mode is worst case for a particular FET.)

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LT8708 How to estimate the NMOS power in Buck-boost mode