TPS22953: Vout drop issue of TPS22953?

Part Number:TPS22953

Dear Sir:

               We follow datasheet page 32 , Figure 63. to design our circuit as below picture, We have a issue as when U4 IN1 turn off and Vout have drop as below picture 2 , Does TI have suggest to us? such as increase output capacitance?

CH1=>+3.8V

CH2=>+VBAT

CH3=>SW1_PG

CH4=>SW2_EN