MSP430F5529: about MSP430F5510 or MSP430F5529 enter LMP4 or LPM4.5

I have a question about MSP430F5529 Low Power. when I use MSP430F5529 enter Low Power 4.5 status,The MCU current flow is 10~22uA,why not is 0.1uA.

when MCU power is 3.3V ,The MCU Low Power current flow is 22uA ，when MCU power is 1.8V,The MCU Low Power Current flow is 0.1uA. would you tell me why,Thanks.

      //This code is about MSP430F5510 enter LPM4.5
      
      //将所有IO口配置为普通IO口
      P1DIR = 0x00;P2DIR = 0x00;P3DIR = 0x00;P4DIR = 0x00;P5DIR = 0x00;P6DIR = 0x00;
      PJDIR = 0x00;
      P1SEL = 0x00;P2SEL = 0x00;P3SEL = 0x00;P4SEL = 0x00;P5SEL = 0x00;P6SEL = 0x00;

      // 端口配置为下拉
//        P1REN = 0x00;//disabled Pullup or pulldown
//        P2REN = 0x00;
//        P3REN = 0x00;
//        P4REN = 0x00;
//        P5REN = 0x00;
//        P6REN = 0x00;

        // 端口配置为上拉
       P1REN = 0xFF;//disabled Pullup or pulldown
       P2REN = 0xFF;
       P3REN = 0xFF;
       P4REN = 0xFF;
       P5REN = 0xFF;
       P6REN = 0xFF;

      GPIO_ExtInt_Init();

//      UCSCTL4=UCSCTL4&(~(SELS_7|SELM_7))|SELS_1|SELM_1;
     //将SMCLK和MCLK配置为VLOCLK

      UCSCTL8 &= ~MCLKREQEN;
      UCSCTL8 &= ~ACLKREQEN;
      UCSCTL8 &= ~SMCLKREQEN;
      UCSCTL8 &= ~MODOSCREQEN;


      /* UCSCTL4&(~(SELS_7|SELM_7))这一语句相当于先把SELS和SELM清零*/
//   UCSCTL4=UCSCTL4&(~(SELS_7|SELM_7|SELA_7))|SELS_1|SELM_1;
  //将SMCLK和MCLK配置为VLOCLK

      PMMCTL0_H = PMMPW_H;                // Open PMM Registers for write
      PMMCTL0_L |= PMMREGOFF;             // and set PMMREGOFF

       SVSMLCTL &= ~SVMLE;   //关闭SVML模块
      SVSMLCTL &= ~SVSLE;   //关闭SVS模块

      SVSMHCTL &= ~SVSHE;
      SVSMHCTL &= ~SVMHE;

      PM5CTL0 &= ~LOCKLPM5;       //清除LOCKLPM5，解除端口状态锁定 锁定所有端口状态，
                                  //   必须在此之前将所有端口的状态改变为最低功耗，锁定。

      PMMCTL0_H = 0;     // Lock PMM Registers

    
      __bis_SR_register(LPM4_bits + GIE);