SNVSBI6 January 2021 LM5156 , LM51561
PRODUCTION DATA
The total loss of the boost converter (P_{TOTAL}) can be expressed as the sum of the losses in the device (P_{IC}), MOSFET power losses (P_{Q}), diode power losses (P_{D}), inductor power losses (P_{L}), and the loss in the sense resistor (P_{RS}).
P_{IC} can be separated into gate driving loss (P_{G}) and the losses caused by quiescent current (P_{IQ}).
Each power loss is approximately calculated as follows:
I_{VIN} and I_{VOUT} values in each mode can be found in the supply current section of Section 8.5.
P_{Q} can be separated into switching loss (P_{Q(SW)}) and conduction loss (P_{Q(COND)}).
Each power loss is approximately calculated as follows:
t_{R} and t_{F} are the rise and fall times of the low-side N-channel MOSFET device. I_{SUPPLY} is the input supply current of the boost converter.
R_{DS(ON)} is the on-resistance of the MOSFET and is specified in the MOSFET data sheet. Consider the R_{DS(ON)} increase due to self-heating.
P_{D} can be separated into diode conduction loss (P_{VF}) and reverse recovery loss (P_{RR}).
Each power loss is approximately calculated as follows:
Q_{RR} is the reverse recovery charge of the diode and is specified in the diode data sheet. Reverse recovery characteristics of the diode strongly affect efficiency, especially when the output voltage is high.
P_{L} is the sum of DCR loss (P_{DCR}) and AC core loss (P_{AC}). DCR is the DC resistance of inductor which is mentioned in the inductor data sheet.
Each power loss is approximately calculated as follows:
∆I is the peak-to-peak inductor current ripple. K, α, and β are core dependent factors which can be provided by the inductor manufacturer.
P_{RS} is calculated as follows:
Efficiency of the power converter can be estimated as follows: