能否将ENx引脚直接与logic high连接起来？相当于一直使能每个桥臂，通时间仍由PWMx控制？
datasheet里指出“To ensure that the bootstrap capacitor is charged enough to turn on the high-side MOSFET, each time that the ENx pin transitions from low to active high, the low-side MOSFET for that phase is turned on for a short pulse (tLS). This occurs regardless of the state of the PWMx input pin.”
意思是每次ENx由低到高，会给自举电容充电。那如果将ENx一直置高，是否就没有ENx由低到高的变化过程，从而也不会给上桥充电？
