Bootstrap detector (BSD) and soft-start embedded in Type III compensation (SSEC) are implemented in the switch-mode charger to achieve high efficiency and ensure robustness charging process. The proposed BSD monitors the bootstrap voltage to avoid low efficiency and serious burning problem in both synchronous and non-synchronous charging modes. On the other hand, the SSEC avoids inrush current in start-up procedure of charger system without any external components and auxiliary circuits to greatly minimize the chip and footprint areas. The proposed robust switch-mode charger with the BSD and the SSEC technique was simulated in 0.25 μm CMOS process. The fast charge current in constant current stage varies from 600 mA to 10 A with a 1.6 MHz operating switching frequency.