可以不用的,你看一下芯片内部结构,请参考楼上的解释。
在数据手册中是这样说明的:
During the transition between the high-side switch and low-side switch, the body diode of the low-side power MOSFET conducts the inductor current. The forward voltage of this body diode is high. An optional Schottky diode may be paralleled between the SW pin and GND pin to improve overall efficiency. Table 2 lists example Schottky diodes and their Manufacturers.
如果对电源的要求不是特别高,那么可以不加二极管。