你好：
TPS55340
SYNC脚怎么接，Datasheet 描述如下：
SYNC 5 6 Switching frequency synchronization pin. An external clock signal can be used to set the
switching frequency between 200 kHz and 1.0 MHz. If not used, this pin should be tied to
AGND.
switching frequency between 200 kHz and 1.0 MHz. If not used, this pin should be tied to
AGND.
但workbench和后面的应用示例图中，SYNC是NC。
怎么处理，还是两种方法都可以？
