Figure 9-5 and Figure 9-6 show the buck-boost converter efficiency versus load current with different inductors and peak current modes. A minimum inductance value of 3 µH is preferred for the buck-boost converter so that the di/dt across the inductor is not too high. This leaves enough margin for the control loop to respond. As a result, the maximum di/dt of the inductor is limited to 6 A/µs. On the other hand, large inductance also limits the transient response for stable output voltage, and it is preferred to have inductors less than 10 µH.

VDD = 12 V

TJ = 25 °C

Figure 9-3 Buck-Boost Efficiency vs Load When I_BBSW,PK = I_BBSW,PK(low)

VDD = 12 V

TJ = 25 °C

Figure 9-4 Buck-Boost Efficiency vs Load When I_BBSW,PK = I_{BBSW,PK(high)}